737-800 Landing Procedure

 
 

737-800 Transocean Air on finals Komatsu (RJNK) Japan © redlegsfan21 from Vandalia, OH, United States, JA8991 (24643740539), CC BY-SA 2.0

In this article I will discuss the techniques used to land the 737-800 aircraft.  

The choice of landing approach is often influenced by considerations such as the specific criteria required for the approach, the desired level of automation, and the individual pilot's preference and technique. Regardless, the method used to actually land the aircraft is similar in all approach types.

The first part of the article discusses techniques used in the approach, descent and landing.  This is followed by a short recap regarding situational awareness, which is critical in any approach and landing.  At the end there is a downloadable step guide explaining the procedure to land the 737-800.

Discussing landing technique without addressing the approach is counter intuitive.  As such, a generic style approach has been ‘loosely’ used to provide a frame of reference.  Furthermore, in an effort to ensure clarity and provide sufficient context, certain information discussed in previous articles may have been reiterated. I purposely have not discussed the requirements for a specific approach type, nor have I included, or discussed detailed checklists.

I have attempted to include as much information as possible which, can have a tendency to make the subject appear complicated; it is not complicated.  Carefully read the information and note that:

  • There is a considerable variability in how the 737 is flown.  Certainly there are wrong ways to do things, however, there is no single right way to do it; and,

  • Airline policy often dictates how an approach is flown based on whether it is a Precision Approach or a Non Precision Approach.

Generally speaking, an approach can be segregated into three segments:

  • The initial approach;

  • The landing approach (descent phase); and,

  • The final approach (landing phase).

Discussion

Initial Approach

Technically, the approach starts when entering the traffic pattern, terminal airspace or at the Initial Approach Fix (IAF), which is published on the approach chart.  However, not all approaches have an IAF, and some require that the airplane be vectored to the final approach course by Air Traffic Control.   Even if there is an IAF, ATC may still decide to vector a plane to the final approach course to make more efficient use of airspace.

Prior to reaching the IAF, or receiving vectors to final, the flight crew should have prepared the aircraft for approach, briefed the crew, and begun to slow the aircraft.  Workload increases considerably during the descent; therefore, it is sensible to complete whatever can be completed prior to the descent point. Descent planning and preparation is usually completed before the initial approach segment begins, which is approximately 25 miles from the runway.

Important Points:

  • Approach planning should be completed prior to the descent point; preferably completed before reaching the IAF.

  • In general, unless indicated otherwise, a flight crew will want the aircraft at approximately 3000 ft AGL no less than 10 NM from the runway.

Landing Approach

The landing approach begins at the Final Approach Fix (FAF). However, the terminology will differ depending upon the type of approach being flown. For the purposes of this article, I will use the term Final Approach Fix (FAF) to indicate the decent point.

Precision and non precision approaches will have the required descent point indicated on the approach chart, which will differ depending upon the approach type selected.

When reaching the FAF, the aircraft will in all probability be controlled by the autopilot with guidance being controlled by LNAV and VNAV (or another pitch/roll mode).

Depending on the type of approach chosen, the aircraft will be transitioning from level flight to either a step-down approach (SDA) or a continuous descent approach (CDA).  Step-down approaches are rarely used today; continuous descent approaches are more the norm.  A CDA, unless otherwise stated on the approach chart, uses a 3 degree glide path.

If you examine the two approach charts (click to enlarge) you will note that the VOR 06 approach shows the descent point at HERAI at 1455 ft AGL. The point is marked by a Maltese Cross and is also shown as the FAF (Final Approach Fix) in the distance legend. Also note that both a step down and a continuous approach is displayed on the chart. In the second chart (ILS 06) the descent point is shown as a LOC (localizer) at 1964 ft AGL and the FAF is noted in the distance legend. Note the chart is also annotated IF (Initial Fix). Different charts will display different annotations.

The reason for showing these two charts, is to demonstrate that the descent point and distance from the runway to begin the descent, will change depending upon the approach type selected from the FMC (assuming an approach from the FMC is used).

 

RJNK VOR 06

 

RJNK ILS 06

 

‘Loose’ Recommendation

As I have already mentioned, there are multiple ways to approach and land the 737; ask several pilots and each opinion will be slightly different. Generally speaking, without alternate guidance from Air Traffic Control or an approach chart, the following recommendations should be adhered to. The aircraft should begin descent to the runway at:

  • Approximately 10 NM from the runway;

  • At approximately 3000 ft AFE;

  • Have flaps 1 extended; and,

  • Be flying at as airspeed no greater than 200 kias.

If the aircraft is following the ILS approach course, it is better to intercept the ILS glideslope slightly from below rather than above. Intercepting the glideslope from below enables greater control of airspeed.

Speed Management

Speed management is probably the most critical factor during any approach.  A common saying is ‘you have to slow down to get down’. This said, it is a bit of a conundrum. The airline wants its pilots to optimise the aircraft’s airspeed for as long as possible, because this means less fuel use, less noise, and lower engine operation times.

Slowing the 737-800 aircraft is not easy when the aircraft is descending, so it is a good idea to begin to reduce the airspeed when the aircraft is in level flight prior to beginning the descent. The thrust levers should be brought to idle (idle thrust or near to) and the airspeed allowed to decay to the flaps UP maneuvering speed.  The flaps UP indication is displayed on the speed tape in the PFD. If speed reduction is initiated before reaching the IAF, the airspeed will decay naturally without use of the speedbrake. 

Important Points:

  • It requires approximately 25 seconds and 2 NM to decelerate the 737-800 from 280 kias to 250 kias, and it will take a little longer decelerating from 250 kias to 210 kias. More simply written, it takes approximately 1 NM to decrease airspeed by 10 kias in level flight.

  • The aircraft should begin slowing at 15 NM from the airport to be at 10 NM at 3000 ft AFE at a speed of approximately 190-200 kias with flaps 1 extended.

  • The aircraft’s airspeed should be reduced to flaps UP maneuvering speed no later than the IAF.

Speedbrake and Flaps Use

The transition from level flight to descent will be much easier, with less need to use the speedbrake, if the aircraft is already at a lower airspeed prior to the descent.  If the speedbrake must be used, try to minimise its use at and beyond flaps 5.  With flaps 15 extended the speedbrake should be retracted. The speedbrake should not be used below 1000 ft AGL. 

Although the speedbrake is designed to slow the aircraft, its use causes increased inside cabin buffeting and noise, decreases fuel efficiency, and can lead to unnecessary spooling of the engines; these factors are exacerbated if the aircraft is descending and travelling at a slower speed. If the speedbrake is to be used during the descent, lower the speedbrake (clean configuration) before adding thrust, otherwise thrust settings will need to be adjusted.

It must be stressed that using the flaps to slow down by creating more drag is not good technique and is frowned upon.  Additionally, continual use of the flaps to slow an aircraft can cause damage to the flaps mechanism over a period of time - adhere to the flaps extension schedule (discussed shortly).

If the aircraft’s speed is too high and the approach is too fast, lowering the landing gear early is an excellent way to slow the aircraft, but bear in mind that this will also increase drag, generate noise, and increase fuel consumption.  This should only be done as a last resort.

Important Points:

  • Whenever the speedbrake is used, the pilot flying should keep his hand on the speedbrake lever. This helps to prevent inadvertently leaving the speedbrake lever extended. 

  • Flaps, in principle, are not designed to slow the aircraft (although their drag does, by default, slow the aircraft); the aircraft’s pitch, thrust, and the use of the speedbrake do this.

Flaps Extension Schedule

All to often novice virtual flyers do not adhere to the flaps extension schedule.  Extending the flaps at the incorrect airspeed can cause high aircraft attitudes, unnecessary spooling of engines, excessive noise, and increased fuel consumption which can lead to an unstable approach. If the flaps are extended at the correct airspeed, the transition will be relatively smooth with minimal engine spooling.

The correct method to extend the flaps is to extend the next flaps increment when the airspeed passes through the previous flaps increment.  For example, when the airspeed passes through the flaps 1 indication, displayed on the speed tape in the PFD, select flaps 2.

The 737 has 8 flap positions excluding flaps UP.  It is not necessary to use all of them.  Flight crews will often miss flaps 2 going from flaps 1 to flaps 5. Similarly, flaps 10 may not be extended going from flaps 5 directly to flaps 15 and flaps 25 maybe jumped over selecting flaps 30. Flaps 30 in the norm for most landings with flaps 40 being reserved for short-field landings or when there is minimum landing distance. In the case of using flaps 40, flaps 25 is normally extended.

My preference is to use flaps 25 as it makes the approach a little more stable. However, if you are conducting a delayed flaps approach, selecting flaps 25 may not give you enough time to extend flaps 30 or 40 and complete the landing checklist before transitioning below ~ 1500 feet AGL.

Flaps 40

The use of flaps 40 should not be underestimated, as aircraft roll out is significantly reduced and better visibility is afforded over the nose of the aircraft (because of a lower nose-up attitude). Because the landing point is more visible, some flight crews regularly use flaps 40 in low visibility approaches (CAT II & III). If the aircraft’s weight is high, the runway is wet, or there is a tailwind, flaps 40 is beneficial. A drawback to using flaps 40, however, is the very slow airspeed (less maneuverability) and higher thrust required. For this reason, if there are gusting winds it is better to use flaps 30.

Advantages

  • Less roll out;

  • Better visibility over the nose of the aircraft due to lower nose-up attitude;

  • Less wear and tear to brakes as the brakes are generating less heat (faster turn around times);

  • Less chance of a tail strike because of slightly lower nose-up attitude during flare;

  • More latent energy available for reverse thrust (see note); and,

  • Helpful when there is a tailwind, runway is wet, or aircraft weight is high.

Disadvantages

  • Increased fuel consumption (negligible unless flaps 40 are extended some distance from runway);

  • Increased drag equating to increased noise (flaps 40 generates ~10% additional thrust); and,

  • Less maneuvering ability.

NOTE: When the aircraft has flaps 40 extended, the drag is greater requiring a higher %N1 to maintain airspeed. This higher N1 takes longer to spool down when the thrust levers are brought to idle during the flare; this enables more energy to be initially transferred to reverse thrust. Therefore, during a flaps 40 landing more energy is available to be directed to reverse thrust, as opposed to a flaps 30 landing.

Important Point:

  • Correct management of the flaps is selecting the next lower speed as the additional drag of the flaps begins to take effect.   

 

TABLE 1: Flaps Extension Table. The table does not include flaps 2, 10 & 25. © JAL-V

 

Maneuvering Margin

The maneuvering margin refers to the airspeed safety envelope in which the aircraft can be easily maneuvered.  This is pertinent during descent, as when the aircraft slows down its ability to maneuver is less than optimal.  An adequate margin of safety exists when the airspeed is at, or slightly above the speed required with the flaps extended.  This is displayed as a white carrot in the speed tape in the PFD. 

Procedure Turns

A procedure turn (PT) is a maneuver to perform a course reversal to establish the aircraft inbound on an intermediate or final approach course. They are often used when flying a VOR approach. If carrying out a procedure turn to intercept the localizer and FAF, try to be at flaps 5 maneuvering speed, with flaps 5 extended, prior to localizer capture and descent.

Pitch and Power Settings (Fly By The Numbers)

Whenever the aircraft is flown by hand (manual flight), pitch and power settings become important.  A common method used by experienced pilots is to fly by the numbers.

The term fly by the numbers is when the pilot positions the thrust levers commensurate to a desired %N1 pursuant with the aircraft’s attitude, configuration and speed.  The %N1 is based on aircraft weight and is displayed in the EICAS.   If the published figures are not available, a reasonable baseline %N1 to begin with is around 55%N1.  Aircraft with heavier weights will require higher thrust settings while lower thrust settings will be needed for lighter weights.  The thrust setting is arbitrary and %N1 will need be fine-tuned with small adjustments.

Once the thrust has been set, always allow the thrust to stabilise for a few seconds and ensure that both thrust levers display an identical %N1.  If you fail to do this, and the thrust settings are slightly offset (despite the thrust levers being beside each other) the aircraft will turn in the direction of least thrust (asymmetric thrust).

During the descent, %N1 may be close to idle thrust, however, as the flaps are extended and the landing gear is lowered, the %N1 will need to be increased to counter the effects of drag. The approximate figure of %55N1 should be set immediately prior to the landing gear being lowered.

Important Points:

  • The %N1 is a baseline figure, the correct %N1 will depend on the weight of the aircraft and any wind component. 

  • Set %N1 immediately prior to lowering the landing gear and extending flaps 15.

It is almost miraculous that once the correct thrust has been set, the others numbers that relate to airspeed and rate of descent fall into place, and the aircraft will only require small incremental adjustments to maintain a 3 degree glide path.

Recommendation:

  • In order to gauge how the aircraft reacts during an approach, fly several automated approaches (the easiest to fly is the ILS Approach).  Observe the thrust settings (%N1) as you extend the flaps and lower the landing gear.  Note the numbers for the particular weight of the aircraft. 

Reaching the Initial Approach Fix (IAF)

As discussed above, the IAF will differ between approach types. The two most important aspects that should be completed just prior to reaching the IAF are:

  • The landing briefing and tasks completed; and,

  • The aircraft’s airspeed should be at flaps UP maneuvering speed, or at flaps 1 maneuvering speed.

Reaching the Descent Point (FAF)

Ideally the aircraft will be at flaps UP maneuvering speed no later than the IAF. If this is done, the transition from level flight to descent will be much easier. At the very latest, plan to be at, or just before the FAF at flaps UP or flaps 1 maneuvering speed.   If concerned that the airspeed is too fast, slow the aircraft to a speed that corresponds to the flaps 1 or flaps 2 indications displayed on the speed tape.   The airspeed will usually fall between 210-190 kias

The point at which the aircraft descends will depend on the approach type used, but If the aircraft’s airspeed has been managed appropriately, initiating the descent at the FAF is relatively straightforward.  During descent the aircraft should:

  • Have the thrust levers set to idle thrust (or near to);

  • Have an attitude of approximately 5 degrees nose-up;

  • Maintain a constant rate of descent (sink rate) between ~600-800 ft/min;

  • Be on a constant 3 degree glide path; and,

  • Not have a descent rate greater than 1000 ft/min. 

Important Points:

  • In some situations (for example, whether the aircraft is in level flight or is descending) to initiate the descent, it may be necessary to lower the attitude to below ~5 degrees nose-up, and then increase the attitude to counter any initial airspeed increase, until the appropriate rate of descent and glide path is established.

  • To aid in passenger comfort, steep descents with the aircraft’s nose below the horizon and pointing downwards should be avoided.

If you are uncertain to the glide path being flown, refer to the Flight Path Vector (FPV) in the PFD.

During the initial descent phase:

  • Speed is controlled by pitch; and,

  • Rate of descent is controlled by thrust.

As you transition to the final approach phase, this changes and:

  • Speed is controlled by thrust; and,

  • Rate of descent is controlled by pitch.

Model aircraft is used to visualise various approach and landing attitudes

The above dot points confuse many virtual flyers and trainees alike.  Rather than attempting to visualise this in your mind, use a small model airplane and position the model in a particular flight phase with the correct attitude.  After a while it will make sense and become second nature.

Descent

After initiating the descent in idle thrust and with the aircraft’s attitude set to approximately 5 degrees nose-up, the aircraft’s airspeed will slowly decay.  As the aircraft slows, match the airspeed to the flap indications on the speed tape.   The maximum airspeed during the descent should not exceed Vref +20 or the landing placard speed minus 5 knots – whichever is lower (Boeing FCTM, 2023). 

Vref +20 is indicated by the white carrot on the speed tape, which is displayed when Vref is selected in the CDU. 

Lowering the Landing Gear (General Rule)

A rule of thumb used by many flight crews in favourable weather conditions is to lower the landing gear and select flaps 15 at ~7 NM from the runway threshold.   At this distance, the aircraft’s altitude is ~2500-2000 ft AGL, and then, prior to reaching 1500 ft AGL, select landing flaps (25, 30 and/or 40).  This enables ample time to ensure that the aircraft is stabilised, and to complete the landing tasks and landing checklist. 

As an aid, flight crews typically will place a ring, displayed on the Navigation Display, at the distance that the landing gear is to be lowered. The ring, created in the CDU, provides a visual reference as to when to lower the landing gear. A ring is also often added at the IAF, or at 10 NM from the runway threshold.

Delayed Flaps Approach

Some airlines and pilots use less conservative distances, thereby minimising the time that the aircraft is flying with the landing gear lowered and flaps extended. A delayed flaps approach or minimum noise approach, will usually have the landing gear lowered and flaps 15 extended at 4 NM from the runway. Landing flaps will then be extended very soon after.

Delayed Flaps Approach - Caution

While lowering the landing gear and extending the landing flaps close to the runway threshold has positive benefits to the airline, and does limit the noise generated, it is not without its problems. Potential problems are:

  • If there is a landing gear or flaps failure, the aircraft is very close to the ground;

  • The landing checklist must be done quickly when concentration may be needed elsewhere (landing);

  • If the aircraft’s airspeed is too high, slowing down is difficult at this late time; and,

  • If windshear or other weather related events occur the aircraft is very close to the ground with minimal room to escape.

When the landing gear is lowered and the landing flaps are extended, the aerodynamics of the aircraft are significantly changed. The pilot must be prepared to adjust the flight controls (pitch and thrust) to maintain control; this is especially so when hand-flying the aircraft. Being in close proximity to the ground at this stage can amplify the risk of a ground strike should the pilot have difficulty adapting to the altered aerodynamics.

Lowering the landing gear and extending the flaps, at a distance of 7-5 nautical miles from the runway, provides additional time and a crucial safety buffer for the pilot to acclimate to the new aerodynamic conditions.

Important Points:

  • The 737-800 is renown for being slippery and difficult to slow down, which is why it is recommended to slow the aircraft prior to the FAF. 

  • A Rule of Thumb often used is: It takes approximately 3 NM to loose 1000 ft of altitude (assuming flaps UP maneuvering speed).

  • A delayed flaps landing should be attempted only in optimal weather conditions.

If you slow the aircraft prior to reaching the IAF, maintain the correct thrust settings to aircraft weight, and extend the flaps at their correct speeds, the descent and approach will usually be within acceptable limits. You will also not have to use the speedbrake.

Stabilised Approach

During the final approach the aircraft must be stabilised; if the approach becomes unstable and the aircraft descends below 1000 feet AFE in IMC, or 500 feet AFE in VMC, an immediate go around must be initiated.

An approach is considered stable when the following parameters are not exceeded:

  • The aircraft is on the correct flight path;

  • Only small changes in heading and path are needed to maintain the correct flight path;

  • The power settings for the engines are appropriate to the aircraft’s configuration;

  • The aircraft’s airspeed is no more than Vref +20 kias and not less than Vref (plus wind component); and,

  • The descent rate of the aircraft is no greater than 1000 ft/min (no special briefing).

Stability during an approach is made considerably easier if the aircraft:

  • Is travelling at the correct airspeed;

  • Is trimmed correctly for neutral stick.

  • The flaps are extended at the correct flaps/speed ratio;

  • The attitude (pitch) is correct; and,

  • The thrust settings are commensurate with the desired airspeed and rate of descent.

My preference is to have the aircraft stabilised with the landing check list completed by 1500 feet AFE. At this point, the autopilot and autothrottle are disengaged and the aircraft is flown manually. Although the handoff can be done later, doing it at ~1500 feet enables enough time to take control of the aircraft and make any final adjustments from automated to manual flight.

Important Point:

  • The height that an aircraft must be stabised is often dictated by airline policy. The height typically is between 1500-1000 feet AFE, but can vary between operators.

Final Approach

The final approach, flare and touchdown occurs very quickly. 

At 500 ft AGL, the pilot should begin to include the outside environment in their scan. This adjustment allows for better situational awareness and helps in preparing for a smooth landing.

As the aircraft descends further to 200 ft AGL, the approach becomes predominantly visual. During this phase, the pilot relies heavily on external visual references to maintain proper alignment of the aircraft (runway cues, approach lighting, and other visual references).

Select a part of the runway where you want to the land (use the runway aiming markers) and adjust the attitude of the aircraft so that it is aimed at this location.  For guidance, the runway centerline should be running between your legs.

As the aircraft flies over the runway threshold (piano keys) and when you hear the fifty call-out, adjust your viewpoint from the aiming point to approximately 3/4s down the runway.  I find looking at the end of the runway works well, as I can see the horizon which aids in determining if the wings are level and in determining the sink rate.

Flare and Touchdown

The flare is a term used to describe the raising of the aircraft’s nose, by approximately 2-3 degrees nose-up (from whatever attitude the aircraft is in), to slow the aircraft to a speed suitable for landing (Vref).

The aircraft should pass over the threshold of the runway (piano keys) at ~50 ft RA.  Then at ~15 ft RA the flare is instigated by raising of the aircraft’s nose to an angle of ~2-5 degrees nose-up.  This attitude is maintained (held with minimal adjustments) with constant back pressure on the control column, and no trim inputs, until the main landing gear makes contact with the runway (touchdown).  At the same time the thrust levers are slowly and smoothly retarded to idle, and if done correctly, the landing gear will touchdown as the thrust levers reach idle.

The reason the thrust levers are retarded slowly is to help prevent any unwanted nose-down pitch that naturally occurs when thrust is reduced. If the thrust is cut suddenly, the nose of the aircraft has a tendency to drop. 

The duration of the flare ranges from 4-8 seconds and the flare distance, the distance that the aircraft has travelled beyond the runway threshold, is between of ~1000-2000 feet. The difference in the duration of the flare is dependent upon the aircraft’s airspeed when it crosses the runway threshold.

A common mnemonic to remember during the flare is Check/Close/Hold (CCH). Check the attitude, close the thrust levers, and hold the attitude position.

Important Points:

  • Pilots during the flare and landing are more concerned with the attitude (pitch) of the aircraft than the descent rate. If the attitude is correct, the descent rate will be within acceptable bounds.

  • There is space of time between when the throttles are retarded and the %N1 is commensurate with idle thrust.

 

Diagram 1: Runway aiming point and distances from threshold

 

Call-outs

Immediately prior to and during the flare it is important to carefully listen to the radio altitude call-outs; the speed at which these occur indicate the rate of descent.  When the twenty call-out out is heard the flare should begin, as there will be a delay between hearing the call-out out and applying the required control input to initiate the flare (which will be at 15 ft RA).  If the flare is delayed until after the twenty call-out out there is a strong possibly that the landing will have too high a descent rate.

Important Points:

  • The flare can make or break a good landing. It is important to have a thorough understanding of the concept.

  • Do not trim the aircraft when below 500 ft RA.

  • Remember, the pilot flying controls the aircraft. The aircraft does not control the pilot.

Flare Problems

A successful flare to land involves several tasks that are done almost simultaneously.  If the final approach has not gone according to plan, or the pilot is not vigilant, two problems that can occur are:

  1. If the flare attitude is too steep, or the thrust not at idle, the aircraft may go into ground effect and begin to float down the runway. Floating is to be avoided at all costs; the aircraft should be flown onto the runway.

  2. If the height that the flare is instigated is misjudged (too high) the flare distance will be prolonged leading to a possible tail strike. If on the other hand the flare is begun too low, the rate of descent will be high causing a very firm landing with possible damage to the landing gear.

In situations such as this, a go around should be carried out.

Interestingly, during the flare there is a natural tendency to pull back on the control column further than necessary.  This can be quite common with new pilots (at least initially).  Bear in mind this can easily occur and be vigilant so it does not occur.

Some pilots prolong the duration of the flare, or minimise the flare attitude in an attempt to slide the aircraft onto the runway with an almost zero descent rate (often called a greaser, slider or kiss). Whilst ego-inspiring, attempting to do this should be avoided.

Important Points:

  • An aircraft in ground effect is difficult to land, because the air pressure keeps the aircraft airborne. Eventually, the airspeed will decay to a point where the effect ceases, resulting in a heavier than normal landing.  Additionally, ground effect causes the aircraft to consume more runway length than usual.

  • Do not prolong the flare in the hope of a zero descent rate touchdown (slider) A slider style touchdown is not the criteria for a safe landing.

  • Do not prolong the flare, trim, or hold the nose wheel off the runway after landing (for example, trying to slow the aircraft because of a higher than normal airspeed), as this may lead to a tail strike.

Landing Descent Rate

A landing (touchdown) occurs when the main landing gear makes contact with the runway (not the nose wheel).  Ideally, a descent rate between ~ 60-200 ft/min is desired for passenger comfort.  This said, Boeing aircraft can tolerate reasonably high descent rates in the order of 600 ft/min.

Speaking with line pilots regarding what constitutes a hard landing will garner innumerable responses, but most agree that a hard landing is in excess of 250 ft/min.

Slider style landing can cause a shimmy to occur to the landing gear

Interestingly, a slider style landing can be detrimental to the landing gear by causing the wheels to shimmy (left and right vibration), leading to increased wheel maintenance. This is because the landing gear is designed to land on the runway with a certain amount of inertia.  Also, a slider style landing in wet conditions can lead to aircraft skidding.  In wet and icy conditions, it is desirable to have a firm landing to aid in tyre adhesion to the runway.

If the aircraft is travelling at the correct airspeed, has the correct attitude, and the thrust levers are reduced to idle at the correct time, the aircraft will land at a reasonable descent rate.

Things to Consider (situational awareness)

During the approach and landing phase of flight, maintaining situational awareness is crucial. Pilots must be fully aware of the aircraft's altitude, and position in relation to the runway, terrain, and other aircraft in the vicinity. This level of awareness, often referred to as situational or positional awareness, is essential for safe and efficient landing operations.

 Important Point:

  • It is important to take advantage of electronic aids to assist in situational awareness. 

The following (at a minimum) is recommended to increase situational awareness:

  • Create distance rings from the runway threshold.  For example, a ring at 10 miles and a ring a 7 miles (CDU);

  • Select an appropriate approach type from the FMC (ILS, RNAV, VOR, IAN, etc);

  • Set the Navigation Display (ND) to Map mode;

  • Turn on the various navigation display aids for the ND (waypoints, station, airports, range rings, etc) by selecting them on the EFIS;

  • Select the Vertical Situation Display (VSD);

  • Display the Flight Path Vector (FPV) on the PFD by pressing FPV on the EFIS;

  • Display range rings by pressing the EFIS knob;

  • Turn on TCAS on the by pressing the TFC button on the EFIS; and,

  • Set the EFIS to terrain.

Another aid frequently forgotten about is the Vertical Bearing Indicator (VBI).  The VBI is an ideal way to determine the correct rate of descent to a known point. The VBI can be accessed from the descent page in the CDU.

Depending on the approach type selected from the FMC, the PFD will display critical information relevant to the chosen approach. The pilot can either use automation to fly the approach, or if hand flying follow the pitch and roll guidance markers. The Navigation Display (ND) in MAP mode, displays a clear overview of the aircraft's lateral and vertical position in relation to the designated navigation aids.

The information that is available is impressive, but sometimes too much information is not a good thing; a cluttered display can cause confusion and a time delay understanding the data displayed. Nearly all flight crews use the Captain and First Officer ND to display different snippets of information depending upon who is flying the aircraft and how they want to view the information.

Auto Brakes and Reverse Thrust

The auto brakes should be disarmed as the aircraft approaches 60 knots ground speed and prior to reverse thrust being reduced. This reduces the jolt that can occur when the auto brakes are disarmed.

Reverse thrust should be engaged, without delay, when the aircraft’s main wheels land on the runway. Typically, maximum reverse is not used, but whether maximum reverse thrust is used or not will depend on environmental factors, runway length, aircraft speeds, and other variables.

Reverse trust should be maintained until approaching 60 knots, then following the 60 knots call-out, reverse thrust should be slowly reduced to reverse idle. if done correctly, the thrust will be at reverse idle when you reach taxi speed. Wait until the generated reverse thrust has bleed off, then slowly close the reversers and place them in the stow position

Control Column Movements - how much is too much

It is evident from various discussions on forums, that a number of virtual pilots do not understand how much movement of the control column is considered normal. This is exacerbated by U-Tube videos of pilots aggressively moving the yoke in real aircraft at low altitudes. Often this leads to these individuals re-calibrating their controls in flight simulator to mimic what they have seen in various videos.

Understandably, many virtual pilots have not piloted a real 737; many have flown light aircraft, however, the control movements in a light aircraft such as Cessna are completely different to those in the 737.

First, many of the U-Tube videos do not provide any input to what the crosswind and gust component was during the landings in question.  In windy conditions, control movements (that also include the rudder) may require a more heavy handed approach, however, without this information gauging technique is impossible.

Second, there are three types of individuals: those that at excel their chosen profession, those that get by, and those that should not be in the profession at all.  Which type of individual is flying the aircraft in the U-Tube videos ? If an approach is moderately unstable, and the aircraft is piloted by a below average pilot, then they may be moving the control column erratically as they try to bring the aircraft back onto station.

Many of the U-Tube videos are uploaded to generate clicks - not to teach correct technique, and erratically moving the control column may, in their mind, instill excitement that the approach is difficult but manageable. In other words, excitement brings clicks… I have not even touched upon the ‘look at what I can do’ philosophy.

Moving the control column when flying the 737 should be done smoothly, and during the approach the movements should be relatively minor with incremental adjustments to pitch and roll.  The more aggressive the movement, the more the aircraft will alter its position, requiring yet further adjustment to bring the aircraft back into line (yo-yo effect). 

If you are needing to make large movements of the control column to keep the aircraft on course (minimal crosswind), then there is a strong possibility that the calibration of the control column is not correct, or the control column has not been correctly calibrated in Windows.


Step Guide To Landing the 737-800

To Land - Summary

To land the 737-800, the general idea is to gradually slow the aircraft to an airspeed which at the beginning of the descent will, at idle thrust, enable the aircraft to descend on a 3 degree glide path to the runway.

As the airspeed decays, the flaps are extended as per the flaps extension schedule.  The thrust levers, rather than being continually adjusted, which can cause engine spooling, are set to approximately 55%N1 with the ultimate aim of airspeed not exceeding (going under) Vref+20.

At approximately 7 NM from the runway, the landing gear is lowered and flaps 15 extended.  Flaps 30 and/or flaps 40 are extended as the aircraft’s airspeed decays to Vref +5.  At this point the landing checklist is completed; the aircraft should be stabilised by 1500 ft AGL.

After crossing the runway threshold at 50 ft RA, the aircraft is flared at approximately 15 ft RA by raising the aircraft’s nose 2-5 degrees nose-up and simultaneously bringing the thrust levers to idle.

Notes:

  • Please read the discussion article prior to reading this document as it will make the guide easier to understand.

  • This guide primarily discusses the landing of the 737-800.  A generic style approach has been ‘loosely’ used to provide context. In this guide, the Final Approach Fix (FAF) has been used to signify the descent point.

  • There are numerous ways to fly the 737 aircraft, however, the landing technique has little room for variation.

Important Points:

  • This guide assumes manual flight (hand flying). If using full or part automation, disconnect the autopilot and autothrottle at ~1500-1000 ft AGL and land manually.

  • Speed Check refers to a possible adjustment of pitch or thrust following a change in the aerodynamics of the aircraft. For example, extending flaps or lowering the landing gear.

Prior to Initial Approach Fix (IAF)

1.       Aim to be at 10,000 feet (250 kias) at 30 miles from runway.

2.      Complete initial descent briefing prior to the IAF and configure the aircraft’s avionics and instruments for the chosen approach.

  • The IAF (location, distance from runway, and altitude) is printed on the approach chart.

3.       Reduce airspeed to the flaps UP indication on the speed tape (usually approximately 210 kias) prior to reaching the IAF.

  • Reduce airspeed in level flight.

  • Bring the thrust levers to thrust idle; the aircraft’s airspeed will slowly decay.

  • When reaching or passing through flaps UP select flaps 1.

  • Correct flap procedure is to extend the next flap increment at, or passing through the previous flap increment.

4.       Reduce airspeed to ~190 kias and extend appropriate flaps increment as per the flaps extension schedule (usually flaps 1).

  • Note that the above airspeeds may differ slightly depending on the weight of the aircraft.

Beginning Descent

1.       Complete the approach checklist.

  • The approach chart will indicate at what point you should begin a descent.  In the absence of an approach chart, then an approximate altitude and distance to begin descent is ~ 4000-3000 feet AGL ~ 12-10 NM from the runway threshold (use rule of thumb: 3 NM/1000 ft loss in altitude).

2.      At the FAF, reduce thrust to idle (or near to) and raise the aircraft’s nose to an attitude of ~5 degrees nose-up

  • Note that the attitude may differ depending upon circumstance).

3. If not already at, extend flaps 5 (flaps 1 to flaps 5 jumping flaps 2). Airspeed will be approximately 190 kias.

  • Speed Check.

  • The pitch may need to be adjusted to maintain desired airspeed.

  • If the aircraft is travelling too fast, or ATC have advised to slow down, consider slowing the airspeed to ~180 kias and extending flaps 10.  If necessary, increase thrust to maintain descent rate.

  • For a step-down approach, use the same procedure as mentioned above, with the added step that you must anticipate what the aircraft will do when you level off at the end of the step-down.  At the level off, you will need to adjust pitch for level flight and probably need to increase thrust.  In both scenarios, the Flight Path Vector (FPV) can be very helpful in determining the attitude of the aircraft.

4. During the descent, try to maintain a descent rate of 600-800 ft/min

  • Do not exceed 1000 ft/min (unless a special briefing has been carried out for a non-standard approach).

5. The aircraft should descend on a 3 degree glide path

  • Use the speedbrake sparingly, especially after beginning your descent.

  • Adhere to the flaps extension schedule.  Correct management of the flaps is selecting the next lower speed as the additional drag of the flaps begins to take effect.  This minimises engine spooling and increases passenger comfort in addition to making the flaps transition smooth.

  • Anticipate what the aircraft will do when you extend the flaps.  The flaps will cause increased drag which, assuming you want to maintain the same airspeed and rate of descent, will either require a decrease in pitch or an increase in thrust.

  • During the descent, the aircraft’s airspeed will decay.  As the airspeed passes through the flap indications on the speed tape extend the next flaps increment. 

6. Do not exceed (go under) Vref +20.

  • Vref +20 is displayed as a white carrot on the speed tape in the PFD (displayed after setting Vref in the CDU).

7.       As the aircraft nears the outer marker, or is ~ 8-7 NM from the runway, idle thrust should be increased to ~55%N1

  • If a delayed flaps approach is being carried out, the distance will be 5-4 NM).

  • Note that actual %N1 may differ slightly due to aircraft weight.

  • Increasing %N1 is to counter the effect of drag from the flaps and soon to be the lowered landing gear.  Allow thrust to stabilise for a few seconds.

  • It is a balancing act (based on aircraft weight, airspeed, and drag) to what %N1 is set.  Start with 55%N1 and adjust from here. 

  • The thrust setting that has been set should be enough to compensate for the increased drag from the flaps and landing gear, however, you may need to adjust the thrust setting slightly to maintain the desired airspeed and rate of descent.  Think ahead and factor this into your pitch and thrust settings. 

  • Increase the thrust immediately prior to lowering the landing gear and extending flaps 15.

8.       At the outer marker, or at ~7 NM from the runway threshold, or between 2400-2000 feet AGL, lower the landing gear

  • There is no absolute rule as to when to lower the landing gear.  The longer you delay, the less noise and fuel will be used.  I find that anywhere between 7-5 NM works well (weather dependent).

  • If you are carrying out a delayed flaps approach, then the landing gear is usually lowered at 5-4 NM.   (distance may change depending upon pilot preference and airline policy). In this case, the increase %N1 should occur immediately before lowering the landing gear.

9.       Immediately after lowering the landing gear, extend flaps 15

  • Speed Check.

  • The drag will increase dramatically after lowering the landing gear and extending flaps 15.  Plan ahead and if necessary decrease pitch and/or increase thrust.

10.   Arm the speedbrake.

11.   Set the Missed Approach Altitude in the altitude window of the MCP.

12.   Complete the landing checklist.

Final Approach

1.       At ~ 5-4 NM from the runway threshold, and at an altitude greater than 1500 feet AGL, extend landing flaps.

  • Extend flaps 30 jumping flaps 25 unless flaps 40 is being used, in which case you would extend flaps 25.

  • Speed Check.

2.       At this point the aircraft’s airspeed will be very close to Vref +5 and the aircraft will be closing rapidly on the runway threshold.

  • Add wing/gust component if necessary to Vref +5.

3.       Raise the aircraft’s nose to an attitude of ~2.5 degrees nose-up.

4.       Decrease the aircraft’s descent rate to ~ 500-600 ft/min

  • This will aid in the transition to the flare by slightly increasing the nose-up attitude.

  • At 1500 ft RA each pilot’s deviation alerting system self tests upon becoming armed.  The test will display on the PFD an amber coloured localizer deviation that will intermittently flash for 2 seconds.

  • Depending upon airline policy, the aircraft must be stabilised between 1500-1000 ft AFE.

For example, QANTAS state that the aircraft must be stable by 1000 ft RA with a attitude pitch of 1-3 degrees nose-up.

Landing, Flare and Reverse Thrust

1.       Select a part of the runway where you want to the land (use the runway aiming markers).

2. Adjust the attitude of the aircraft so that it is aimed at this location

  • For guidance, the runway centerline should be running between your legs.

2.       As the aircraft passes over the runway threshold (piano keys), adjust your aiming point to approximately 3/4 down the runway

  • When crossing the runway threshold and beginning the flare, focus your eyes on the end of the runway and watch the horizon. This helps to gauge whether the aircraft wings are level.

3.       The height that the aircraft should be at when crossing the runway threshold is ~ 50 feet AGL.

4.       At ~15 feet RA, initiate the flare and increase the aircraft’s attitude ~ 2-3 degrees nose-up.

  • Listen for the RA call-outs. At the RA 20 call-out begin the flare (this is because by the time your brain has processed the call-out and you have moved the control column, the aircraft will be at RA 15 ft.

  • Maintain back pressure on the control column to keep the attitude constant until the aircraft’s main gear touches down.  If the flare has been done correctly, the main gear will touchdown simultaneously with the thrust levers reaching idle.

  • When initiating the flare, the increased attitude will decay the +5 kias plus any gust correction that was added to Vref. The aircraft’s main gear should touchdown at Vref.

  • During the flare smoothly bring the thrust levers to idle.  Do not suddenly chop the thrust.

5.       Ideally the aircraft’s descent rate, when landing, will be 200 ft/min or less.

6.       Lower the nose wheel without delay by smoothly flying the nose wheel onto the runway. 

  • Control column movement forward of neutral should not be required.

7.       Engage reverse thrust and check that spoilers have engaged. 

8.       Verify that speedbrake lever is down.

9.       Disarm the auto brakes as the aircraft approaches 60 knots ground speed.

10.   Approaching 60 knots ground speed, and only after hearing the 60 knots call, begin to slowly retard reverse thrust.

  • The reversers should be at reverse idle as you reach taxi speed.  Maintain reverse idle for a few seconds to enable the reverse thrust to fully dissipate.  Close and stow the reversers.

11.   Apply manual braking as required.

Important Points:

  • Below ~ 200 feet AGL the landing is primarily visual.

  • To assist in gauging the flare, focus your eyes nearer to the end of the runway and watch the horizon (which should be horizontal).

  • A go around (TOGA) can be instigated at anytime prior to landing touchdown.

Final Call

Although approach types differ, the technique of landing the 737 is identical in each approach.  By far the most critical elements of a successful approach and landing are speed management, extending the flaps on schedule, thrust settings and using the correct attitude during the flare. Despite a number of variables occurring in quick succession, with experience, you can easily maintain a constant speed, attitude and descent rate as you fly down the 3 degree glide path.

Related Articles

Glossary

  • AFE – Above Field Elevation

  • AGL – Above Ground Level

  • Attitude – Synonymous with pitch.  The angle that airflow hits the wing. 

  • DFA – Delayed Flap Approach

  • DH (A) – Decision Height (or Decision Altitude). If not visual, the approach cannot continue (Precision Approach)

  • EFIS – Electronic Flight Instrument System

  • ILS – Instrument Landing System

  • IMC – Instrument Meteorological Conditions

  • KIAS – Knots Indicated Airspeed

  • MAP – Map display (forms part of Navigation Display)

  • MAA - Missed Approach Altitude

  • MDA - Minimum Decent Altitude. If not visual, the aircraft cannot descend lower than this altitude (Non Precision Approach)

  • ND – Navigation Display

  • NM - Nautical Miles

  • PFD - Primary Flight Display

  • Pitch – Synonymous with attitude.  The direction of the aircraft relative to the horizon.

  • RA – Radio Altitude

  • VMC – Visual Meteorological Conditions

  •  ~ Symbol for approximate 

Review and Updates

  • 09 April 2024 - review and release of .pdf.

  • 19 May 2024 - partial rewrite to improve clarity.

Autobrake System - Review and Procedures

air berlin 737-700 -  autobrake set, flaps 30, spoilers deployed, reverse thrust engaged (Marcela, GFDL 1.2 www.gnu.org/licenses/old-licenses/fdl-1.2.html, via Wikimedia Commons)

The autobrake, the components which are located on center panel of the Main Instrument Panel (MIP), is designed as a deceleration aid to slow an aircraft on landing.  The system uses pressure, generated from the hydraulic system B, to provide deceleration for pre-selected deceleration rates and for rejected takeoff (RTO). An earlier post discussed Rejected Takeoff procedures.  This article will discuss the autobrake system.

General

The autobrake selector knob (rotary switch) has four settings: RTO (rejected takeoff), 1, 2, 3 and MAX (maximum).  Settings 1, 2 and 3 and RTO can be armed by turning the selector; but, MAX can only be set by simultaneously pulling the selector knob outwards and turning to the right; this is a safety feature to eliminate the chance that the selector is set to MAX accidentally.  

When the selector knob is turned, the system will do an automatic self-test.  If the test is not successful and a problem is encountered, the auto brake disarm light will illuminate amber.

The autobrake can be disengaged by turning it to OFF, by activating the toe brakes, or by advancing the throttles; which deactivation method used depends upon the circumstances and pilot discretion.  Furthermore, the deceleration level can be changed prior to, or after touchdown by moving the autobrake selector knob to any setting other than OFF.  During the landing, the pressure applied to the brakes will alter depending upon other controls employed to assist in deceleration, such as thrust reversers and spoilers.

The numerals 1, 2, 3 and MAX provide an indication to the severity of braking that will be applied when the aircraft lands (assuming the autobrake is set).

In general, setting 1 and 2 are the norm with 3 being used for wet runways or very short runways.  MAX is very rarely used and when activated the braking potential is similar to that of a rejected take off; passenger comfort is jeopardized and it is common for passenger items sitting on the cabin floor to move forward during a MAX braking operation.  If a runway is very long and environmental conditions good, then a pilot may decide to not use autobrakes favouring manual braking.

Often, but not always, the airline will have a policy to what level of braking can or cannot be used; this is to either minimize aircraft wear and tear and/or to facilitate passenger comfort. 

The pressure in PSI applied to the autobrake and the applicable deceleration is as follows:

  • Autobrake setting 1 - 1250 PSI equates to 4 ft per second squared.

  • Autobrake setting 2 - 1500 PSI equates to 5 ft per second squared.

  • Autobrake setting 3 - 2000 PSI equates to 7.2 ft per second squared.

  • Autobrake setting MAX and RTO - 3000 PSI equates to 14 ft per second (above 80 knots) and 12 ft per second squared (below 80 knots).

Conditions

To autobrake will engage upon landing, when the following conditions are met:

  • The appropriate setting on the auto brake selector knob (1, 2, 3 or MAX) is set;

  • The throttle thrust levers are in the idle position immediately prior to touchdown; and,  

  • The main wheels spin-up.

If the autobrake has not been selected before landing, it can still be engaged after touchdown, providing the aircraft has not decelerated below 60 knots. Setting the autobrake usually forms part of the approach cehcklist.

To disengage the autobrake system, any one of the following conditions must be met:

  1. The autobrake selector knob is turned to OFF (autobrake disarm annunciator will not illuminate);

  2. The speed brake lever is moved to the down detent position;

  3. The thrust levers are advanced from idle to forward thrust (except during the first 3 seconds of landing); or,

  4. Either pilot applies manual braking.

The last three points (2, 3 and 4) will cause the autobrake disarm annunciator to illuminate for 2 seconds before extinguishing.

Important Facet

It is important to grasp that the 737 NG does not use the maximum braking power for a particular setting (maximum pressure), but rather the maximum programmed deceleration rate (predetermined deceleration rate).  Maximum pressure can only be achieved by fully depressing the brake pedals or during an RTO operation.  Therefore, each setting (other than full manual braking and RTO) will produce a predetermined deceleration rate, independent of aircraft weight, runway length, type, slope and environmental conditions.

Autobrake Disarm Annunciator

The autobrake disarm annunciator is coloured amber and illuminates momentarily when the following conditions are met:

  • Self-test when RTO is selected on the ground;

  • A malfunction of the system (annunciator remains illuminated - takeoff prohibited);

  • Disarming the system by manual braking;

  • Disarming the system by moving the speed brake lever from the UP position to the DOWN detente position; and,

  • If a landing is made with the selector knob set to RTO (not cycled through off after takeoff).  (If this occurs, the autobrakes are not armed and will not engage.  The autobrake annunciator remains illuminated amber).

The annunciator will extinguish in the following conditions:

  • Autobrake logic is satisfied and autobrakes are in armed mode; and,

  • Thrust levers are advanced after the aircraft has landed, or during an RTO operation.  (There is a 3 second delay before the annunciator extinguishes after the aircraft has landed).

Preferences for Use of Autobrakes and Anti-skid

When conditions are less than ideal (shorter and wet runways, crosswinds), many flight crews prefer to use the autobrake rather than use manual braking, and devote their attention to the use of rudder for directional control.   As one B737 pilot stated - ‘The machine does the braking and I maintain directional control’.

Anti-skid automatically activates during all autobraking operations and is designed to give maximum efficiency to the brakes, preventing brakes from stopping the rotation of the wheel, thereby ensuring maximum braking efficiency.  Anti-skid operates in a similar fashion to the braking on a modern automobile.

Anti-skid is not simulated in FSX/FS10 or in ProSim737 (at the time of writing).

To read about converting an OEM Autobrake.

B737-800 NG EVAC Panel - A Nice-looking Panel

oem 737-800 evacuation panel (evac)

A quick post to showcase an OEM evacuation (EVAC) panel. The panel is usually mounted in the AFT overhead; however, as I am still developing the overhead panels I have temporarily installed it into the center pedestal.  

The EVAC panel’s use needs no introduction – it is triggered by the flight crew if and when evacuation of the aircraft is required / occurring.  A switch in the passenger cabin can be triggered by the cabin crew alerting the flight crew that an evacuation is imminent.  The panel is only used when on the ground (obviously).

The EVAC panel is from a 737-800 and the functionality includes: an arming/off switch, flashing red coloured EVAC annunciation, alarm cancelling pull knob, and a piecing alarm (horn). 

The panel is not connected to any function within Flight Simulator; therefore, an interface card is not required.  A continuity test, using a multimeter, is used to determine which pins in the Canon plug correspond to which switch/toggle/alarm.  The backlighting is powered by 5 Volts whilst the alarm and annunciator is 28 Volts.

Although the panel serves no true function in the simulator, it is a good-looking panel that improves the aesthetics of the center pedestal.  Once the overhead is fully developed the EVAC panel will be removed from the pedestal and placed in the aft overhead panel (the correct location).

The EVAC panel is an airline option.

Below is a video showing the panel’s use.

 

737-800 EVAC panel operation

 

Sheepskin Seat Cover added to Weber Captain-side Seat

sheepskin seat cover added to oem weber seat

Sometime ago I acquired a pair of Weber pilot seats which came with the correct Boeing diamond-pattern, grey honeycomb seat covers.  However, one of the seat covers was slightly damaged.  The lower cover was also a tad on the small side and kept popping off the rear section of the lower cushion when you sat on it.  Not a major problem, but it was slowly becoming irritating having to repeatedly attach the cover back on the cushion.

The small size was probably caused by the previous owner washing the seat cover;  Boeing covers are renowned to shrink substantially when washed in hot water!  To rectify these minor problems, I decided to have the captain’s side upgraded to a sheepskin seat cover.

A friend of mine has access to high quality Boeing-style sheepskins and being a wizard at sewing, agreed to retrofit the cover for me.

It should be noted that sheepskin covers are not attached to the seat like you would do on an automobile.  Rather, the sheepskin is sewn directly onto the existing fabric of the original seat cover.  Colour varies somewhat depending upon the manufacturer awarded the Boeing contract, but in general they are grey to tan in colour.

I think you will agree, that the final outcome looks, and certainly feels, much better than the original damaged and too small seat cover.

Ground Effect - Historical Perspective & Technical Explanation

usaaf b17 flying fortress (USAAF, B17-F-45-VE (cropped), marked as public domain, more details on Wikimedia Commons)

During the Second World War, a crippled Boeing B17 was struggling to maintain altitude.  The aircraft and eleven crew members were over occupied Europe, returning to England, following a successful bombing mission.

Searchlights, Flak & Enemy Fighters

After negotiating the enemy searchlights that probed the darkness over their target, and then being struck by shell fragments from anti-aircraft flak, they were pounced upon by German fighters on their homeward leg.  The ensuring fight was dramatic and left the damaged bomber with only two engines running and third engine having difficulty.  As the bomber approached France, the enemy fighters, starved of fuel, aborted their repetitive attacks, but the damage had been done.  Loosing airspeed and altitude the aircraft could not maintain contact with the Bomb Group; soon they were alone.

The captain, in an attempt to maintain altitude, requested that everything heavy be jettisoned from the aircraft.  This included machine guns, ammunition and damaged radio equipment; soon the B17 was a flying skeleton if its former self.

The Captain was concerned that a fire may develop in engine number three as it was spluttering due to a fuel problem.  The Captain did not need to concern himself much longer, for the engine began to cough uncontrollably before vibrating and ceasing to function.   The aircraft was now only flying on one engine – something not recommended, as it placed great strain on the engine and aircraft superstructure.  

The aircraft continued to loose altitude despite the jettisoning of unwanted equipment.  The Captain decided it was better to ditch into the English Channel rather than land in occupied France.  His thinking was that Air Sea Rescue maybe able to pick them up, if their repeated morse code (SOS) had been received by England.  The power of one engine was nowhere enough to maintain such a large and heavy aircraft and the crew prepared to ditch into the freezing cold water of the channel.

We’re Going In – Good Luck Boys!

“Get ready guys, we’re 300 feet above the water” yelled the Captain into his intercom system.  “As soon as we hit bust them bubbles and get out.  Try to get a raft afloat”.  “Link up in the water  – Good Luck!”

Everyone expected the worse.  Surviving a ditching was one thing, but surviving in the cold water of the English Channel in winter was another!  The rear gunner, since moving forward sat close to escape hatch and gingerly rubbed his rabbit’s foot; he had carried this on every mission.  The side gunner fumbled repeatedly with his “lucky” rubber band, the bombardier sat in private thoughts, a photograph of his loved one held tightly in his hand, and the navigator frantically punched his morse set trying to get the last message out before fate took command of the situation.

The aircraft, although trimmed correctly, slowly began to dip towards the sea.  But at 60 odd feet above the waves, the aircraft began to float  – it felt as if the aircraft was gliding on a thermal.  For some reason the aircraft didn't wish to descend.  The remaining engine screamed its protest at being run at full throttle, however the horizontal glide continued. 

The Captain was amazed and thankful for whatever was keeping this large aircraft from crashing into the sea.  It was as if the B17 was cruising on a magic carpet of air – why didn’t it crash.  

A tail-wind assisted in pushing the B17 toward England and safety; seeing the English coast in sight, the navigator quickly calculated a route to the nearest airfield closest to the coast.  Twenty minutes later the bomber lumbered over the runway.  The only way to land was to reduce power to the remaining engine and push the control wheel forward, thereby lowering the pitch angle.  They were home and safe!

Divine Interaction, Luck, or Skill ?

The crew thought it was divine interaction that the bomber had not crashed – or perhaps luck!

Aviation engineers were baffled to what had occurred.  The aircraft had glided many miles above the surface of the English Channel and had not crashed.  Boeing, in an attempt to unravel what had occurred, repeated the event in the confines of a wind tunnel, to realize that what had maintained the large aircraft airborne was not divine interaction, but the interaction of what has since been termed Ground Effect.

The above account, although embellished in detail, did occur.  The mishaps of this bomber during the Second World War demonstrated a previously unknown phenomenon - Ground Effect.

Ground Effect – Technical Explanation

Ground effect refers to the increased lift and decreased drag that an aircraft wing generates when an aircraft is about one wing-span's length or less over the ground (or surface).  The effect of ground effect is likened to floating above the ground - especially when landing.

When an aircraft is flying at an altitude that is approximately at, or below the same length of the aircraft's wingspan, there is, depending on airfoil and aircraft design, a noticeable ground effect. This is caused primarily by the ground interrupting the wingtip vortices, and the down wash behind the wing. 

diagram 1: ground effect in the air

When a wing is flown very close to the ground, wingtip vortices are unable to form effectively due to the obstruction of the ground. The result is lower induced drag, which increases the speed and lift of the aircraft.

The two diagrams depict aircraft in ground effect whilst on the ground and in the air.

diagram 2: ground effect on the ground

A wing generates lift, in part, due to the difference in air pressure gradients between the upper and lower wing surfaces. During normal flight, the upper wing surface experiences reduced static air pressure and the lower surface comparatively higher static air pressure. These air pressure differences also accelerate the mass of air downwards.  Flying close to a surface increases air pressure on the lower wing surface, known as the ram or cushion effect, and thereby improves the aircraft lift-to-drag ratio.  As the wing gets lower to the surface (the ground), the ground effect becomes more pronounced.

While in the ground effect, the wing will require a lower angle of attack to produce the same amount of lift. If the angle of attack and velocity remain constant, an increase in the lift coefficient will result, which accounts for the floating effect. Ground effect will also alter thrust versus velocity, in that reducing induced drag will require less thrust to maintain the same velocity.

The best way to describe ground effect and which many people, both pilots and passengers, have encountered is the floating effect during the landing flare.

Low winged aircraft are more affected by ground effect than high wing aircraft. Due to the change in up-wash, down-wash, and wingtip vortices there may be errors in the airspeed system while in ground effect due to changes in the local pressure at the static source.

Another important issue regarding ground effect is that the makeup of the surface directly affects the intensity; this is to say that a concrete or other hard surface will produce more interference than a grass or water surface.

Problems Associated With Ground Effect

Take Off

Ground effect should be taken into account when a take-off from a short runway is planned, the aircraft is loaded to maximum weight, or the ambient temperature is high (hot).

Although ground effect may allow the airplane to become airborne at a speed that is below the recommended take-off speed, climb performance will be less than optimal.  Ground effect may allow an overloaded aircraft to fly at shorter take off distances and at lower engine thrust than normal.  However, the aircraft will not have the ability to climb out of ground effect and eventually will cease to fly, or hit something after the runway length is exceeded.

Approach and Landing

As the airplane descends on approach and enters ground effect, the pilot experiences a floating sensation which is a result from the increased lift and decreased induced drag value. Less drag also means a lack of deceleration and could become a problem on short runways were roll-out distance is limited.

Therefore, it's important that power is throttled back as soon as the airplane is flared over the threshold and the weight of the airplane is transferred from the wings to the wheels as soon as possible.

How to Counter Ground Effect

To minimise ground effect on landing, the following must be addressed:

  • Pitch angle should be reduced to maintain a shallow decent (reduces ability of the wing to produce more lift).

  • Thrust should be decreased.

  • The power should be throttled back as you cross the threshold at ~RA 50 feet (note that in simulation ~10-15 feet is more effective).

  • Land the aircraft onto the runway with purpose and determination.  Do not try and grease the aircraft to the runway (often called a carpet landing).  The weight of the aircraft must be transferred to the wheels as soon as possible to aid in tyre adhesion to the runway (also important when landing in wet conditions).

Does Ground Effect Occur in Flight Simulator?

If the aircraft is not set-up correctly, ground effect will definitely be experienced in a flight simulator. 

If you have ever wondered why, after reducing speed on an otherwise perfect approach, your aircraft appears to be floating down the runway, then you have already experienced ground effect.

Construction Commenced - New Platform to Install OEM Control Columns

I thought it time to post what’s happening with regard to the construction of the simulator.  Additions and improvements are in the pipeline and it’s hoped that OEM control columns and a new platform will be installed very shortly.

Currently the simulator is mounted on a fiber-board and wood platform, which I constructed when I received my Main Instrument Panel (MIP) just before Christmas 2010.  The platform has served me very well and was perfect for the installation of the ACE yoke and Precision Flight Controls (PFC) rudder pedals.  

Soon after constructing the platform and purchasing the ACE yoke, I was able to secure two OEM B737-500 control columns. I was surprised to find these units so quickly and I was fortunate that my timing coincided with the dismantling of a late model B737-500.

Fitting the OEM control columns to the wooden platform appeared to be problematic, as the platform was a tad low in height and it was awkward to retrofit the linking rod that connects the control columns for duel operation.  Therefore, I decided that a new platform was required; custom designed  to fit the control columns.

Aluminium Modular Design

Rather than use wood and fiber-board, I selected aluminium tubing cut appropriately and TIG welded together.  To facilitate future transport, the platform has been constructed in modular form.  The forward portion comprises three modules bolted together in strategic places, while the rear part of the platform (not shown), where the seats and center pedestal reside, abuts snugly to the forward section.  It’s intended to use high density ¼ inch plastic/vinyl as the upper cover on the platform  as this material is easier to work than aluminium sheeting, is light in weight, very strong and comes from the factory in Boeing grey.

In the photographs (click to enlarge) you can see the control columns (striped completely) fitted to the forward modular section of the platform.  The control columns are connected to each other by a ¾ inch heavy duty shaft and heavy-duty double bearings.  Forward and aft movement of the control column is controlled by a heavy duty spring and left and right roll movement is controlled by another spring. 

Control Column Pull Pressures

The pull pressure on the control column is set to 24 pound which is slightly less that the standard pull in the B737 which is 34 pound.  The pull can be easily altered by moving the spring forward or backward on the spring retainer.  The pressure on the roll component is presently 12 pounds.  I've been told the roll pressure as per the Boeing maintenance manual is +_15 pound; therefore, I'm well within the ball park.

CP Flight ADF Radio Modules - Review

cp flight ADF radio, NAV 1/2 and M-Comm communication module (Flight Deck Solutions).  Note the use of oem 737 DZUS fasteners

CP Flight in Italy is well known for its production of quality simulator parts, in particular their Main Control Panel (MCP) units that work out of the box – literally plug and fly.  This short review is for the ADF Radio modules that I have recently installed into the simulator center pedestal to replace the radios made by SISMO Solicones. Although this short review pertains to the ADF radios, all CP Flight modules are made similarly to the same quality and utilise the same methods of connection.

ADF radios may appear “old school” with many virtual flyers more concerned in learning and understanding the more modern LNAV, VNAV and GPS navigation systems.  It’s important to realize that not all countries comply with the aviation regulations enforced within the United States (FAA).  Many developing nations still use VOR and ADF stations as the primarily means of approach.  Further, knowing how to use and having the appropriate equipment installed to be able to follow these “older style” navigation beacons is often good practice for redundancy and to cross check the results from primary navigation.  Using VOR and ADF navigation is also more challenging, interesting and enjoyable.

Construction and Appearance

The modules are constructed using the same technique that CP Flight uses to produce all their modules and panels.  Each upper panel is made from CNC machined acrylic which produces a very crisp finish and allows any letter cut-outs to be very well defined.  The electronics board, rather than being left “naked” like other manufacturers, is sealed within a lightly constructed metal case.  To allow the user to drop the module directly onto the pedestal rails, each module has overlapping wings that conform to the width of the rail.  To ensure long life, the ADF radio modules incorporate dual concentric rotary encoders with stainless stems rather than plastic stems.

Inspecting the pictures of the ADF radios. you will observe a thin line of light between each illuminated digit.  This is not visible in true life and is only an artifact of using a rather long shutter speed to take the photograph.

High Quality

The knobs and switches, which are custom machine injected, are true to life and are tactile in feel.  As you click through the frequencies the movement is stable and well defined.  There is no catching as the knobs are turned.  The push keys on the units are plastic moulded, backlit and work flawlessly; they do not stick in the down position when depressed, and click back into position when pressure is released.  The frequency displays are 7 segment digits and are very easy to read.  Digit colours are in amber yellow. 

The upper panel of the module is attached to the electronic circuitry within the lower section by a metal backing plate; this increases the strength of the unit and assists in the dissipation of heat.  The modules are a well presented piece of avionics that accurately replicates the functionality found in the real 737 navigation radio. The panel is 1:1 with the OEM counterpart.

A light metal case protects internal electronics and two 5 pin DIN plugs supply connection and power to and from the radio and to other CP Flight components

No System Boards and Daisy Chaining

The modules do not require control boards - they are completely stand-alone.  This minimises the wiring involved and the challenge of finding another location for yet another I/O card.  However, to operate the modules you will require either the CP Flight Main Control Panel (MCP) or the 737MIP board.  Both of these devices provide the power and ability for the modules to connect to and communicate with the main computer and FSX.

CP Flight uses what has to be one of the simplest methods for module connection – daisy chaining.  Daisy chaining is when you have several modules linked by 5 pin DIN style connectors and one cable.  The cables connect in relay between whatever modules you are using and eventually link to either the CP Flight Main Control Panel (MCP) or 737MIP board for connection to the computer via a single USB cable.

Boeing Grey

All CP Flight B737 series modules and panels are professionally painted in "Boeing grey".  I’m not sure how many thin coats of paint are applied, but to date I have experienced no problems with regard to paint chipping or flaking.  Although this last comment may appear trivial, the quality of paint is important.  The modules will be used for many years and during the course of operation, you will be placing pens, clipboards, charts, coffee cups, etc on the center pedestal and the modules.  Further, as the units are flat, dust will accumulate requiring dusting and cleaning.  Low quality paint will scratch, fade and wear thin with time.

The observant will note that there is a difference in colour shade between the modules made by CP Flight and Flight Deck Solutions.  A purist may argue that this is not realistic, however, I disagree.  Through time, Boeing has used several shades of what has been coined "Boeing Grey" and it is not unrealistic to have modules sporting different shades of the baseline colour.  Different avionics manufacturers (in the real world) also use different colour shades of "Boeing grey". 

DZUS Complaint

If you are utilising real aircraft parts in your simulator, in particular a center pedestal, then any module that is DZUS complaint is advantageous as it allows for the module to be dropped directly onto the DZUS rails and secured by the DZUS fasteners.  Unfortunately CP Flight fails in this area as their modules are not DZUS complaint.  Each module has the appropriate holes drilled; however, they only fit replica DZUS fasteners (supplied).  The width of the hole is too small to install genuine DZUS fasteners; you will be required to drill the hole a little larger to accommodate the genuine B737 fastener.

This picture illustrates the fit of the CP Flight ATC panel to the rails of an oem center pedestal Each panel is very closely aligned to the holes in the rail enabling the replacement of reproduction dzus fasteners with oem dzus fasteners

Back-Lighting

The ADF modules are back-lit by several strategically placed LED lights.  This is commonplace within the industry with the exception of some high-end suppliers such as Flight Deck Solutions which use their own IBL back lighting systems utilising real aircraft bulbs.  I have no issue with the back lighting and the module is evenly lit, illuminating all cut out letters.

CP Flight Module Set-up

The modules are stand-alone and do not requite software to be installed for operation – they are plug and fly; however, to connect the modules (via daisy chaining) to the computer via a single USB cable, either requires the CP Flight Main Control Panel (MCP) which acts as a power source amongst other things, or the dedicated 737MIP board.  Software is required for the operation of the MCP and 737MIP board and can be downloaded from the CP Flight website.  The software is easy to install and to configure. 

Downside – Ghosting of COM Port

I’ve already discussed the simplicity of daisy chaining and the benefits of not needing to use a multitude of wires and I/O cards; but, everything comes at a price and CP Flight’s “Achilles Heel”, is the method they have chosen to connect everything to the computer.

Modules are connected to and from each other and to the MCP or 737MIP board via daisy chaining.  The MCP or 737MIP board provides the power to run the module and allow information to travel between the computer and the module. The MCP or 737MIP board is then connected to the computer via a single USB cable.  To connect to the computer requires that a COM port is ghosted to replicate a serial port. 

Whilst this process is automatic, and occurs when power is applied to the MCP or 737MIP board, many users experience problems with the software ghosting the port.  Usually the ghosting issue is solved with appropriate drivers and once the connection is made once, rarely is this problem again experienced.

Reliability and Performance – Software and Modules

Software

No problems, other than the initial connection problems that “maybe” associated with the ghosting of the COM port.

Modules

There is no time lag when altering frequencies; the digits spin as fast as you can turn the dial.  Drop outs have never occurred.  The tone switch operates correctly and always listens for and connects with the correct marker morse tone.  It’s important to note that the tone switch does operate as designed and can be used to switch off the “somewhat annoying” morse tone which is heard, when in range of the ADF.

Support

Support from CP Flight is either directly via e-mail or by a dedicated forum.  The support provided by CP Flight is exemplary.  Paolo from CP Flight stands by the products he sells and every effort is made to ensure your modules work as advertised.  There is absolutely no problem dealing with this company as the owners are very trustworthy and deliver what they promise.

Quick List – Pros & Cons

PROS

  • Well designed & constructed

  • Realistic quality machine-injected switches & stainless rotaries (not plastic)

  • 1:1 to the real B737 series aircraft

  • Good attention to detail

  • Operational morse tone switch

  • Strategically positioned backlighting

  • Very easy to set-up and connect (daisy chaining)

CONS

  • Ghosting of COM port can be an issue when using MCP as connecting equipment (no experience with 737MUIP board)

  • Non DZUS compliant

Overall Opinion

I am very impressed with these modules.  They are solid, well constructed and operate flawlessly out of the box!  The quality of the modules is very high and it’s a pity that they are not made to be DZUS compliant.  They suit the high end enthusiast to professional market.  

My rating for the modules is 9/10

Please note that this review is my opinion and is not endorsed by CP Flight.

737-300 Telephone & Microphone for 737-300 Center Pedestal

737-300 internal communications

I have installed to the rear of the center pedestal the correct telephone and microphone for the 737-300 aircraft.  Neither item is necessary, but it adds to aesthetics and fills the empty gap where the telephone should have been installed.  Although the telephone and microphone are functional, they have not been configured to operate with the avionics suite or flight simulator.

The center pedestal and telephone are not from a 737-800 aircraft, nor would they ever be seen on a Next Generation aircraft; they fill a gap until the respective OEM components can be found.

Sometimes it’s a matter of what is available, or waiting until a part becomes available. In this case, I decided to use what was available.

This type of telephone and microphone (as well as other types depending upon manufacture) were used on the 737-300 through to the 737-500 aircraft.

As you can see from the photograph, this telephone has been there and done that!  The telephone is considerably scratched, but I prefer using part that shows service, rather than using a shinny new reproduction item.

737 Fuel Management Program

fuel planner user interface

Flight planning is a large part of flying the 737, in real life and virtually.

Yes you can fly with the three fuel tanks full, however, bear in mind that you will not be simulating a real flight.  Airlines rarely fly an aircraft between two locations with a full fuel load, unless it’s required for operational use or safety. 

Fuel is heavy, and the additional weight requires more power and fuel to move between locations.  This equates to an increased expense.  Airlines usually only carry enough fuel to reach their destination, taxi, and one or two alternate airports.

You can calculate the appropriate load sheets, distances between airports, winds, altitudes to be flown, and alternate airports. But this can be time consuming, and often you don’t want to simulate the paper trail that goes hand in hand with getting a 737 into the air. For those keen on paperwork and simulating everything, I recommend the program TOPCAT - Take-Off and Landing Performance Calculation Tool.

Ross Carlson has created a very handy and functional fuel management tool to use.  The program is stand-alone and does not need to be installed into the flight simulator directory or to C://drive/Programs; the software can be installed to and run from any folder including your desktop.   Initially designed to work with the Boeing 737NG developed by Precision Manuals Development Group, the utility works well for other 737 aircraft, provided they have the same operating limitations and fuel tank capacities that the software was designed.

The only issue to be wary of is that the aircraft you are flying matches the same weights as those used by PMDG.

  • Supports 737-600, 737-700, 737-800 and 737-900.

  • Values can be entered and displayed in pounds or kilograms.

  • Reads payload (passenger and baggage) weights via FSUIPC.

  • Calculates en route fuel burn based on cruise altitude and trip distance.

  • Calculates fuel burn to reach alternate airport.

  • Calculates increased or reduced fuel consumption due to forecast winds en route.

  • Allowances for taxi-out fuel burn, holding fuel burn, and minimum landing fuel.

  • Indicates if any parameters exceed aircraft operating limitations.

  • Sets actual fuel levels in your aircraft via FSUIPC.

  • One simple .exe file, no external DLL or data files required.

  • Loads first 1,000 pounds of fuel into the center tank to keep pumps submerged.

  • Accredited for use with registered non-registered copies of FSUIPC.

Operation

I've been using this fuel planner or quite sometime and it works quite well.  I open a flight and then run the fuel planner and change the variables as required.  Then, after I've boarded the fuel I exit the fuel planner program.

The only let down with the program, and this probably is an advanced feature not deemed necessary when the program was developed, is that it doesn't provide %CG which is used in a CDU to determine your takeoff trim.

Search google for PMDG fuel planner and you will find several sites that allow you to download the program.  Alternatively, download the software from the file download tab.