GE Flight Simulator as Tool to Explore:

                    Landing Technique of Fast Aircraft

                              &  Flight Simulator Landing Accuracy Test


                                         Ralf Vandebergh




As a spaceflight and aeronautics journalist and a regular user of Google Earth, I became fascinated by the built-in flight simulator, especially the F-16 (Falcon or Viper). Because rapid flights from one location to another are possible with this aircraft, it is the most interesting choice for the general user. The views produced by this tool are impressive and very realistic. Over the years I learned to use the simulator also in a more realistic way concerning flight dynamics when I started to compare simulator data to data from the HUD-display of real-life F16 fighter jets. Making realistic landings using an easy program as Google Earth and presenting the experience to others so they can enjoy the fun as well, has become a project.


On this page you will find analyses of landings with the GE F-16 flight simulator compared to landings of real-life F-16's. This way you will learn more about the accuracy of this built-in Google Earth flight simulator which thanks to the simplicity is very suited to learn to understand flight basics. Therefore this is also a demonstration of how to use this Google Earth feature as a learning tool to better understand the basics of flight dynamics and especially the landing technique of aircraft designed for high speed. That is the reason why this site is designed mainly in black & white: to reduce the fantastic amount of data provided by Google Earth to the essential and the main purpose of this site: How flight - and especially landing dynamics of the Google Earth Falcon simulator compare to real data.
This site is not suitable as a general user guide to the Google Earth flight simulator, this sort of manuals can be found sufficient on other places on the web. Additionally there is a chapter about the subject 'steep approaches' which is of special interest for different purposes. With demonstrations of slowly as possible approaches from steep angles while using a minimal length of runway.

On the second page 'Professionally Flying with Google' there are further analyses of the aerodynamic accuracy of the GEF flight simulator including tests on stability and it is demonstrated how to make landings in a professional way. The main subject on this page the stabilized approach, including an aerodynamic experiment that will show that an aircraft on a perfect stabilized approach can virtually land itself.


On the third page GE F-16 In-Flight Analyses, you will find tests on the aerodynamic accuracy of the GE flight simulator during the flight using basic aerobatic maneuvers.



                                                  Google Earth F-16  versus  Real F-16


How is the GE F-16 flight simulator in comparison with the real F-16? Please note that this comparison is only based on flight dynamics, especially the landing, and not the reality of the cockpit. The HUD (Head Up Display) of the Google F-16 shows only the most important flight data such as speed, attitude and altitude, and certainly is the real F-16 HUD looking much more complicated. The reason for the simplicity is clear: The idea for the Google flight simulator is actually to provide the user with an extra feature: flying over the Google maps from the perspective of an aeroplane. Nevertheless, I have found the Google flight simulator display to be very suitable for non-pilots to learn understand flight and landing basics thanks to the simplicity. It would be interesting to find out how the aerodynamics of the simulator compare to the real F-16 and especially during important phases in the flight such as the landing. Following on this site is my analysis. First some explanation about landing technique of fast aircraft.


                                         Flying over Africa with the Google Earth F-16 flight simulator  (Simulated flight: Ralf Vandebergh)                              


 Landing Fast Aircraft

The landing phase of an aircraft is the hardest part of flying, therefore the next comparisons between GE simulations and real flight will be concentrated on the landing. Before executing the comparisons it's good to understand the relation between angle of attack, pitch attitude and airspeed. Angle of attack (AoA) can best be understood as the angle between the direction in which the nose of an aircraft is pointing to and where it is going. The angle of the nose direction with the ground plays no role in determining the angle of attack but determines the pitch attitude of the aircraft. More precisely, angle of attack is determined by the angle between the chord line of an airfoil and the flight path vector. A type aircraft as the F-16 would normally sink at a too high rate to touch down at the desired landing speed, even with full flaps deployed. A larger angle of attack increases lift, therefore the pitch attitude is increased during the approach and the landing to lower the sink rate and to touch down at a vertical speed within limits. Landing the F-16 with a lower nose or pitch angle would require higher landing speeds then usually desired.

A precise definition of Angle of Attack given by Boeing:
Angle of attack (AOA) is the angle between the oncoming air or relative wind and a reference line on the airplane or wing. Sometimes, the reference line is a line connecting the leading edge and trailing edge at some average point on the wing. Most commercial jet airplanes use the fuselage centerline or longitudinal axis as the reference line. It makes no difference what the reference line is, as long as it is used consistently.


                                                 Angle of Attack Maximum (Alpha Max)

An aircraft can fly at its lowest speed just above stall speed without losing height when there is a maximum angle of attack (Alpha Max). With the GE simulator it is easy to try out the principle; Set the flaps to 100 %, fly not too high above the ground - for example 3000 feet, decrease the speed to 130 knots (close to stall speed) by lifting the aircraft nose to about 15 degrees pitch and adjust the thrust to hold that speed. If you are doing it right, you will not sink. As soon as you lower the nose you will start to sink. Note that these values differ considerably with the height caused by the thinner air at higher altitudes. During a test flight at 55.000 feet (16,8 km) I noticed a sink rate of 6000 feet per minute flying at a speed of 195 knots while the pitch angle was 5 degrees. At a much lower altitude the aircraft would climb at a low rate with this speed and pitch angle were it now is sinking at a high rate. For the same reason, the take off and landing speeds of aircraft must be higher on airports located at higher altitudes.

                                                    Flying or Falling with Zero Pitch

Flying with a high alpha is not only necessary at low speeds but also at high altitudes to compensate for the loss of lift due to the thinner air. If the nose or pitch angle is 15 degrees in a level flight, this angle is both the angle of attack (AoA) and the pitch attitude. This is because the angle between the nose attitude and the flight path is 15 degrees (angle of attack) and the angle between the nose attitude and the horizon has the same value (pitch attitude). When an aircraft decreases speed and it starts sinking while we keep the nose pointed to the horizon, the angle of attack is in this situation the angle between the nose attitude and the glide path towards the runway while the pitch is zero. The two extremes: Flying level with the nose to the horizon (AoA=zero) and falling vertically from the sky with the nose to the horizon (AoA=90 degrees).

                                                                 Flying at a high alpha  (credit: DJJakuz, Youtube)                                                                 

                                              Relation between Landing and Alpha Max

If we can fly level at a speed just above stall speed by lifting the aircraft nose up to the right pitch angle, it is not hard to understand that we can use the same procedure in the landings to touch down softly. The only difference is that in the landing we should not fly completely level but we have to touch the runway at some point. Because we can control the amount of lift with the pitch angle, we can control the vertical speed and the sink rate with the nose attitude. For example: If we land on a runway that appears shorter then estimated, we could decide to land faster by pointing the nose lower and descent with a lower angle of attack. This again increases the sink rate and we descent faster, but we also make a rougher landing. Lifting up the nose shortly before touch down (landing flare) is the reverse but it takes longer for the aircraft to settle down on the runway. The flare helps itself to do so with the increased drag caused by the high nose attitude causing the speed to decrease.

                                                   The 2 Purposes of the Landing Flare

Aircraft designed for high speed operations such as fighter jets require a different approach compared to the landing of other planes with better lift characteristics. In practice this means a higher pitch or nose attitude at the practical landing speed and earlier in the landing phase. The higher angle decreases the descent rate and let the aircraft land more softly. In general aircraft landings, the nose is lifted shortly before touchdown to realize softer landings at the landing speed close to stall speed. This maneuver is known as the 'flare'.

Interestingly the second purpose of the flare is exactly the reversed: braking the speed to come to an earlier touch down. This moment should take place at the end of the flare when the angle of attack is increased to the stall point and the wheels almost touch the ground. This is the reason why the stall alarm can appear shortly before the landing. The moment before the landing flare is also the moment the thurst is usually set to zero causing the sink rate to increase again. This is countered by raising the nose even more to the high angle of attack that usually causes the desired stall point.

This stall point occurs with the help of a combination of the effects of the aircraft attitude in the landing configuration: 1: The high pitch angle causes increased drag and as a result the speed decreases. 2: Because the thrust is usually set to zero before the landing this also decreases the speed and as a result the wings stall earlier in the high AoA attitude. Now it becomes clear why a landing sometimes is called a 'controlled stall'.

                                                       F-16 'Long Duration Flare'

During the construction of this website I came across an interesting question as to what we actually consider as a 'flare'. An F-16 type aircraft needs more velocity to stay in the air then normal aircraft, therefore the angle of attack is increased more to counter the loss of lift due to the decreasing speed for landing. The landing flare of most other types of airplanes that is usually executed shortly before touch down has the same principle as the longer duration pitch maneuver of the F-16: To increase the angle of attack and thus to lower the sink rate which makes a soft landing possible.

Understanding this, we could conclude that the landing phase of fighter jets can be seen as a long duration flare with higher AoA. There also can be an additional flare (up to 15 degrees pitch) even with the high AoA, depending on the kind of landing that has to be made. In this case it is interesting to note that it isn't actually a real 'flare', at least not what the word is supposed to mean. On the other side we could consider the long duration approach flare of the F-16 as a part of the normal aircraft flight attitude and not consider it as part of the flare-maneuver. In that case the F-16 flare would be only the pitch angle added to the already high AoA attitude and executed at the nominal flare point shortly before touch down. 

A flare requires longer runways as the landing process takes longer. Landings on very short runways, aircraft carriers for example, are made without the execution of a real flare resulting in rougher but shorter landings. In that case the aircraft descent rate or vertical speed is relatively high. The short runway simulation below illustrates the poor sight on the runway shortly before touch down due to the high pitch attitude.


The procedure of increasing Angle of Attack while decreasing the speed early in the landing procedure prior to the final landing flare is not only common with fighter aircraft but also applied to other aircraft landings. The biggest difference with fast aircraft as the F-16 is that the pitch values are significantly lower. A retired Jumbo Jet pilot who flew the early Boeing 747-100 and 200 types, provided on his website an excellent description.


                                                    Landing on a short runway with the GE F-16 simulator. (Simulation: R.Vandebergh)                  



                            GE F-16 Landing Analyses

                                                                                   Analysis Landing Phase 1


For the following analyses, you have to understand two differences of the real F-16 with the GE simulator. In the real F-16, the speed in knots is displayed as in the left picture (200 knots in this case) and the pitch attitude or nose attitude is displayed as the cross visible on the right picture.



The movie below is a Google Earth flight simulator F-16 landing I made to show the changing pitch (nose) attitude in relation to the decreasing speed in the landing procedure. This standard procedure is also visible well in the short runway landing video in the previous chapter. Although there are always differences between all kind of landings for example due to different approaches, you will find that the procedure that you have to perform to make a good landing is roughly the same. This simulation shows a great comparison with real life F-16 landing footage.

For a normal glide path towards the runway in the proces of decreasing the speed, the nose is lifted above the zero-pitch line when the speed has dropped below roughly 190 knots as visible in the simulation below. From this point, the nose is raised higher as the speed is further dropping. Comparison to real F-16: The point of raising the nose above the zero-pitch line below a speed of approximately 190 knots is also visible in this  real life F-16 video.

Simulated flight by Ralf Vandebergh



                                                                               Analysis Landing Phase 2


From now on, all comparisons will be displayed using still shots out of GE simulations I made (left) and from screenshots from real-life F-16 HUD video's (right). To acquire scientific valuable analyses and to get an overall impression of the accuracy, fragments are used from different GE simulator F-16 landings and real-life F-16 landings.

In the comparison below we see a point in the approach to the runway that is nearly the same in both the simulation and the real flight. At this point, the speed in the simulation is 170 knots. The speed in the real flight as displayed on the F-16 HUD is corresponding with the simulation, as marked at the right. The nose or pitch attitude at this moment in the approach is 5 degrees in the simulation and similar in the real flight.




                                                                              Analysis Landing Phase 3


In the comparison below we are at a point in the landing at around 1000 feet above the ground in a normal glide path. The speed indicator displays 145 knots in the simulation and shows a very similar value in the real F-16 flight. At this point in the approach both the simulation and the real flight show a pitch altitude of 10 degrees or just above this value. Changes in the approach glide angle - for instance a steeper angle - can cause differences in the pitch angle at a certain speed compared to a normal glide angle. A very steep landing for instance, can cause that the nose is still below the zero-pitch line at a speed of 160 knots were it already is above 5 degrees in a normal landing.




                                                                           Analysis Landing Phase 4   


The comparison below shows the phase very close to the landing, almost the point of main gear touch down. The simulation displays a speed of just below 140 knots. The real-life F-16 HUD shows a similar speed at this point. The nose/pitch attitude in this landing-phase is just above 10 degrees in the simulation and in the real-life flight. Not much of a flare was added in both flights. The landing speed may be further reduced to 135 to 130 or even 125 knots very close to stall in certain situations while the corresponding nose/pitch attitude touches the area between 10 and 15 degrees.


There are always differences in speed and pitch values between different landing situations, for instance due to differences in the glide angle or selected landing speed. This applies to real-life flights and simulated flights. The data used for the comparisons in these analyses are from most common and comparable landings with normal glide angle and landing speed. The comparisons in this analysis show that we can conclude that the data from the Google Earth F-16 flight simulator in all 4 analyzed phases in the landing match the data from the real-life F-16 HUD closely.




                                              Steep Approaches

                                                                                Experimental Landing Techniques

Very steep approaches can be useful for example in order to land faster at a nearby airport in the case of an emergency or it can be useful when landing in mountainous terrain. The overall problem of steep approaches is the high speed that is generated due to the deep pitch towards the runway. There are scientifc studies that figure out how to land optimally from the steepest approach possible. A Delft University research paper mentions the use of thrust vectoring technology to de-rotate the aircraft from the high angle of attack approach to a horizontal landing position shortly before touch down. This de-rotation lowers the angle of attack which increases the sink rate. But the thrust deflection caused by the thrust vectoring compensates for this loss of lift. I made the following GE test simulations to illustrate what optimally can be done in the traditional way without additional technology when approaching from a steep or very steep angle with the use of a mininum length of runway. Note that these are just presentations of test flight simulations that I made to try out different experimental landing techniques and to compare them to each other.

                                                         Differences in Flare Execution

The biggest difference concerning the flare between nominal landings and steep landings - especially with a negative or zero pitch angle is the different character of the flare. In nominal landings we start the final approach already with a high pitch angle and high AoA. In fact, the process of the F-16 long duration (pre)-flare has already started at this point: We raise the nose more and more while we decrease the speed to a value just above the landing speed. Finally, shortly before touch down the angle of attack of the F-16 should be high enough to land softly but at the nominal aircraft flare point we may add a small 2-3 degrees final flare for an even softer landing when there is sufficient length of runway available. In steep approaches with a negative pitch angle the execution of the entire process of the flare is accelerated, because the airspeed is higher and we have to change the pitch over a larger angle.

This concludes that > the lower the pitch angle, the faster the execution of the flare <. For instance: We fly a steep approach of -10 degrees and the nose is pointed in the direction of the flight path. The angle of attack is in this case zero while the pitch angle is -10 degrees. In order to achieve a flare of +10 degrees we have to change the pitch over 20 degrees. If we are on a normal glide path of -3 degrees and we descent with the nose pointed to the horizon, the angle of attack is -3 degrees in the approach while the pitch is zero. To achieve a +10 degrees flare we only have to change the pitch over 10 degrees. Now it's easy to understand why the execution speed of the flare is higher when the pitch attitude is lower. 1: We have to change the pitch over a larger total angle in a short period of time. 2: The steeper the nose is pointed to the runway, the more airspeed is generated. As a result the flare must be executed at an even higher rate. The examples also show that the angle of attack plays no role in the execution speed of the flare. This is because the rate depends only on the initinal pitch angle while the AoA has no relation to the ground.

                                              The Frozen Flare - A Stabilized Approach

In the previous section we have seen that the rate of the flare execution depends a lot on the steepness of the flight path towards the runway. A low negative pitch requires a faster rate to raise the nose to the flare attitude while a high positive pitch is already close to that desired attitude. There are important limits on both sides of the spectrum. At a given point the angle of approach is too steep to keep the velocity within limits with a result that the drag generated by the flare is not sufficient to brake the speed. A longer runway would be required to start the flare at a higher point above the ground to slowly lower the pitch angle and thus to decrease speed
which would enable a nominal flare.

On the other side of the spectrum there is also a limit for the slowest execution rate of the flare in a minimal steep approach. This limit is the moment were the nose can not be raised more then the point of Alpha Max, the attitude an aircraft can fly at its lowest speed with maximum angle of attack (see chapter Landing fast Aircraft). This means that we theoretically can lower the flare execution rate almost until the point of Alpha Max is reached. At that moment the rate is minimized to zero and in fact we have 'frozen' the flare. If we adjust the thrust in coordination with the pitch angle to keep this attitude, we fly a perfect stabilized approach and in fact the aircraft flies itself to the runway. Note that we could never land an aircraft at exactly the Alpha Max attitude; As we have seen in the chapter Landing fast Aircraft in the section Relation between landing and Alpha Max, we have to deviate from that attitude in order to touch down. Because the sink rate has to be great in a steep approach, it is impossible to fly a steep glide angle in an almost Alpha Max attitude. In the next sections will be demonstated how to find a compromise between the glide path angle and the nose attitude in order to descent as slowly as possible in a steep approach and how to fly the descent still in a stabilized configuration.

                             In a very steep approach, the speed is too high if the nose is just directed downwards without using aerodynamic braking techniques

                                                  Steep Low Speed High-AoA Approach

The used technique in the 2 video's below is to glide a maximum steep approach to the runway at a low as possible speed. The simplicity of the GE flight simulator (no speed brakes for example), guarantees that the used technique in these simulations is based purely on aerodynamics. The lowest possible speed, just above stall speed and sometimes even touching stall speed, makes it possible to fly a slow approach on the steep angle.

The key is to increase drag as much as possible by raising the nose at the right moment in the final approach. In the simulation below can be seen that the speed, initially around 160 knots, is lowered by raising the nose to a higher pitch when the correct angle towards the runway has been reached. At a pitch angle of 3 to 5 degrees, the drag increases rapidly causing the speed to drop to 140 knots and lower. This immediately increases the sink rate. It is now easy to regulate the sink rate with the pitch attitude which changes the angle of attack. If it is nessesary to fall faster to reach the right point of touch down, the nose is lowered. For a more gradual descent, the nose is raised.

The speed will not change much during the descent as demonstrated in both videos. In the first video, the final approach is flown at 130 knots for a large part of the descent, touching the stall speed and you see the stall alarm popping up regularly. Make sure that the speed is not dropping below this alarm rate, otherwise the aircraft will start to become unstable as stall occures. In the simulation it can be seen that the pitch is lowered to decrease drag and increase speed as soon as stall becomes critical. The next (pre-flare) phase can also be seen in both video's below. At an altitude of around 300 feet, the nose is raised from 5 degrees pitch up to 10 degrees pitch while some thrust is added at the same moment. This additional thrust is applied to counter the increased drag from the pre-flare and the flare. The power is cut just at the moment as the flare (up to 14 to 15 degrees) is executed.

 Simulated flight by Ralf Vandebergh


                                                  Very Steep Negative-Pitch Approach

Another steep landing but handled in a different way. This time the pitch angle during a large part of the approach is around -3 degrees (negative). As a result the final approach is more relaxed with a speed of 20-30 knots higher then the critical 130-140 knots just above stall speed used for the steep low speed approaches. The vertical speed during the descent reaches 3300 feet per minute maximum. At an altitude of roughly 1000 feet above the ground, the nose is raised above the zero pitch line and the angle of attack is increasing. At a speed just below 140 knots a maximum pitch angle of around 14 degrees is reached while a stall alarm shows up, followed immediately by main gear touch down and nose gear touch down. Because the sink rate is still considerable during the flare the thrust is shortly increased for a soft touch down when the pitch exceeds 10 degrees. This simulation demonstrates that if a coordinated combination of careful adjustments of airspeed and glide path angle is used, both realized by corrections in the nose attitude, it is possible to end up with sufficient runway to execute a relaxed flare maneuver and to touch down softly. As the entire final approach is flown with the thrust at zero, the only left variable to use for airspeed and glide path angle adjustments is the pitch angle.

Simulated flight by Ralf Vandebergh


                                         Steep Approach Flare - Landing or Ballooning

When the glide path angle is too steep, a high AoA low speed approach is not realizable. To descent on the steep glide path with the nose up, the speed should be post stall - under the stall speed - to realize the required high sink rate. The steep glide angle that generates excessive speed, also disables a nominal flare in a negative pitch approach as demonstrated in the previous section, unless we have a very long runway and we can increase the angle of attack slowly in an earlier phase, floating above the runway and waiting for speed to decrease and to execute a nominal flare.

The following F-16 simulations demonstrate a landing technique simular to a Space Shuttle landing with the difference that the glide slope is different, no pre-flare is used and we have no speedbrakes. To decrease speed coming from the steep approach of a nose angle of -17 to -19 degrees with a maximum descent rate of more then 10.000 feet per minute, the Shuttle landing flare was preceded by a maneuver to an angle of only -1.5 degrees (pre-flare). The landing was made at a touchdown speed of 184 to 196 knots. The final landing flare of the Shuttle was executed at a nose or pitch angle of around 8-10 degrees, comparable to the flare angle that can be seen in the steep landing F-16 simulation below, right.

The 2 simulations below are experimental landings try out out speed braking using the flare. Demonstated is how it is done in a wrong (left) and in a good way (right). If we end up with a speed below roughly 190 knots at the start of the flare, which is much higher then in a nominal landing flare, it is low enough for the flare to brake the speed with the generated drag. Landing is possible but with a higher speed then in a normal approach or in a low speed high AoA steep approach as demonstrated earlier. If the speed is too high at the moment of the flare, we will end up Ballooning back into the air. With sufficent length of runway available, the solution of a too high approach speed is to use a positive low pitch pre-flare, float low above the runway and wait until speed decreases, followed by a nominal flare.

                         Wrong   (Ballooning)                                                    Good   (landing)            


                                                             Simulated flights by Ralf Vandebergh

                                                  Relatively Steep Zero-Pitch Approach

The simulation below shows a landing from a glide angle somewhere between very steep and normal. The approach speed at zero thrust may be higher then in the very steep landings. In this phase, the sink rate is up to about 2000 feet per minute while the speed is slowly dropping below 190 knots. The pitch is around zero degrees (nose pointing to the horizon) for a considerable part of the trajectory. At the start of the flare, the nose is raised above the zero mark when the speed has dropped to about 160 knots. Note that this value differents considerably with the steepness of the glide path that has been taken. For comparison: In a normal approach the nose is raised above zero pitch at around 190 knots (see analysis 1). In the last phase there is a transition to reasonable normal values with a flare angle of around 12 degrees at a landing speed of around 140 knots. In the next section 'Stabilized Zero Pitch Approach' there will be a demonstration of an optimized (stabilized) version of this zero pitch descent.

Simulated flight by Ralf Vandebergh

                                                    Stabilized Zero-Pitch Approach

This simulation demonstrates another steep approach but this time it is flown fairly stabilized. Meant is that in the final approach descent trajectory there is a stable value for speed, pitch and sink rate. The speed is decreased slowly to 150 knots while initially at a low pitch angle in order to lower the velocity with the help of the increased drag. This low pitch is in this case necessary as at the start of the final approach the thrust is already zero while the speed is above the desired 150 knots. When this airspeed is reached then the nose is kept at zero degrees (zero pitch). Demonstrated is that almost the entire final approach can be flown at the constant speed of 150 knots without any pitch (nose at zero degrees) while the sink rate is fairly constant with 2700 feet per minute and remains around this value with only slight deviations until the final flare to a pitch angle of around 14 degrees is executed. During the flare the stall alarm pops up while the landing is made at the nominal touch down speed of just below 140 knots.


Simulated flight by Ralf Vandebergh


                                                                            Landing Samples

Samples of different types of landings with the Google Earth F-16 flight simulator that I made over the past time. This is also the place were now  new video's of simulations will be added. You will find normal landings, steep landings, steep turn landings, touch and go's and new test flights.

                                           Touch and go Hamburg Finkenwerder Airport

                                                      Extremely tight final approach


                                             Spectacular descent and landing California






Google Earth / GE Flight Simulator

Google Earth Blogy

New Google Earth Flight Simulator Tips and Video 2015

General Bibliography Falcon F-16

Technology and the F-16 Fighting Falcon Jet Fighter

Scientific Papers F-16 Landing

Optimization of High Angle-of-Attack Approach and Landing Trajectories

Scientific Papers Landing Flare (general)

The Landing Flare of Large Transport Aircraft

- of Interest

Everybody has an Angle (of Attack)



Twitter:  @ralfvandebergh

                                         All text, animations and screenshots of animations on this site are copyright (c) Ralf Vandebergh