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Hood Flying and Illusions
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Contents
Terminology; …Hood
Training; ...Hood; ...Standard Rate
Turns; ... Timed Turns; ...Unusual
Attitudes; ...Teaching Unusual
Attitudes; ...No More Vertigo; ...Simulation is not
Reality; …Tumbling Gyros; ...VFR to IFR
Options; ...You and Illusions; ...IFR Flying
Faults; ...Vertigo; ...Illusions:;
...Natural Illusions; ...Night
Illusions; ...Variable Visibility; ...Landing
Illusions; ...Visual Deception; ...Black Hole
Landing; Aircraft Illusions; ...IFR for VFR
Pilots; ...Scan ; ...The
Other Instruments Scan; ...Hood
Lessons; ...Vertigo simulation; ...Practice
Illusions; ...Instructional
Use of MS Flight Simulator; …Expecting
Illusions; …Recovery from VFR into
IFR; ...VFR into IFR; ...Night
Light Illusion; ...
Terminology:
--Pipper: The dot between the 'wings' of the attitude indicator. (English) Originally the dot used in aiming aircraft
guns in WWI.
Hood Training
The FAA integrated mix of VFR and IFR instruction is a violation of the very instructional precepts considered basic to flight instruction. The purpose of the IFR instruction to a VFR student was an emergency process. As such, it focused on the attitude indicator and the making of a 180- degree turn out of IFR conditions. The basis of this instruction was upon the inability of a VFR pilot to maintain control in IFR conditions for much over a minute.
The basic 1959 survival turn was performed by reference to the needle with any descent initiated by a slight reduction in power as by applying carburetor heat. The yoke was released and a quarter-needle turn initiated and stopped by rudder alone. Over the years this was changed into a coordinated attitude indicator shallow bank along with turn coordinator rate turn for one minute. Any time devoted to this detracted from the use of VFR references outside the cockpit.
I, along with others, have minimized hood time until giving a concentrated emphasis just prior to the practical test. In my VFR instruction emphasize a light smooth control touch, selected power settings, and attitudes referenced with the nose and horizon set by trim. The transition from such VFR flying to IFR instrument control is a seamless smooth one.
My students learn, early on, to index the throttle position by sound and confirm only with the tachometer. Sound is also indexed for selected speeds and configurations. The student proceeds from a known condition in VFR to an instrument condition directly related and confirmed by the instruments. In years past my students have usually commented on how seamless the VFR to IFR training has been.
There is no way that future flight instruction can permanently reconstruct the problems created by poor initial instruction. The importance of proper initial instruction has been proven many times. Poor coordination, trim techniques, attention to headings and altitudes will never be what they should be if not taught from the beginning.
Hood
The hood should be fitted prior to engine start. Note that the attitude indicator has both a wings level and a level index mark at its top. The 10, 20, and 30 degree bank marks have been pointed out during Dutch-rolls and banks. A plane will not turn if the wings are level. This means that whenever the heading indicator is fixed on a heading the plane is not turning and wings can be considered level. Knowing this will enable you to perform even stalls under the hood. When the attitude indicator is at level, heading will be constant. Confirm this with the heading indicator.
The turn coordinator has the ability to show both the direction of the turn and markings that index the 2 minute standard rate turn. The vertical speed indicator will either indicate false or excessive movement under abrupt control input and may have up to a 12 second lag. The altimeter also may lag. The accuracy of the instruments is proportional to the smoothness of any change. The use of sound indexes acquired from VFR flight will help clue you in on airspeeds and changes.
Standard Rate Turns
All banks under the hood are at standard rate. Standard rate turns requires two minutes to make a 360 degree circle. One minute for a 180 and 30 seconds for each 90 degrees. The standard rate turn for a given airspeed is indicated by the needle or by the turn coordinator. The turn coordinator is the only true indicator of whether the bank is left or right. (A necessary check during spins) The angle can be estimated by dividing the speed by ten and adding five. (Speed /10 + 5 = angle of bank) 85 knots airspeed divided by 10 is 8.5 + 5 = 13.5 angle of bank. Set the estimated angle on the AI and check with the turn coordinator. All climbs and descents are at one bar width on the attitude indicator. From low cruise both climb and descent at a given rate will closely correspond to RPM changes by 100's. A power reduction of 500 rpm gives 500 fpm descent.
Timed Turns
In VFR condition at level altitude cruise the standard rate bank is selected by using the turn coordinator. The degree of bank is NOTED on the attitude indicator. This angle of bank becomes the standard to be used. It is checked for accuracy by making successive timed turns of 90, 180, and 360 degrees. It takes 30 seconds to turn 90 degrees, one minute to turn 180 degrees and two minutes to turn 360 degrees. In a C-150 at cruise the angle will be about 12 degrees. After timed turns are introduced at cruise go to VFR slow flight and determine the angle of bank required on the turn coordinator for above timed turns. The angle will be close to 10 degrees.
Unusual Attitudes
Using Sensory Perception
A large part of flight instruction is based upon how the student perceives the instructor's demonstrations. The instructor, by example, is trying to get the student to replicate a behavior model. The complete original consists of many sub-assemblies of basic perceptions and skills. This reconstruction is made up of visual, auditory, and kinesthetic perceptions.
We begin with the visual sense of what happened. In basics we want this sense to be developed with out-of-the-cockpit vision. The student must then through repetition learn to see and recognize mentally what the eyes see. Visual memory can be recalled and even recreated. When the student can recreate a modeled procedure he has also replicated all the other perceptions and skills.
One of the most neglected areas of modeling perception is sound. Sound is a lead indicator of aircraft performance. The dominance of visual perceptions tends to make the student funnel in on the visual aspects of flying. However, sound, more often than not will lead visual indications. I make a point of emphasizing initial sounds, sound changes, constant sounds, and difference in sounds as they occur in procedures. The proper sequence of sounds in flying can be like music to the attuned.
The hardest of the senses to perceive is the kinesthetic. The near total dominance of the visual makes it override the other senses. However, when we remove the visual from the mix, the kinesthetic is just waiting there to take over. With practice we can learn to use the visual sense to verify or negate our kinesthetic perceptions. When, we can't, vertigo is waiting in the wings to take over the procedure.
The object is to return the plane to straight and level flight at a normal cruise airspeed as quickly as possible. The student is to close his eyes and put his head down or up. The instructor turns, dives, climbs, rolls and pitches the airplane in a designed effort to upset your semicircular canals. Some of the aircraft configuration can be changed as well.
While with his head down the student will feel every move greatly exaggerated, as if the aircraft is doing aerobatics. You are immediately placed in a situation of sensory conflict. Straight and level feels like it is climbing, diving or turning. Strange and unfamiliar sensations puzzle you land you begin to have doubt and uncertainty.
The student should level the wings first. Second LISTEN to the airspeed and then use the throttle as is appropriate. If slow add power; if fast reduce power until level cruise is attained.
Teaching Unusual Attitudes
Let the student get himself into the unusual attitude by having the student read a sectional in his lap while maintaining straight and level while reading. He should shield his eyes from any shadow effects. As the aircraft begins to deviate let it proceed for a few seconds before having the student use instruments to correct the situation. Discussion should reveal whether vertigo occurred.
I had occasion to ride in the Barany Chair, named after the Nobel Prize winning physician, the trip was so disorienting that I could not eat lunch. Not only did I lose my sense of direction, position and situational awareness, I lost what lunch I tried to eat. The sensory information from my inner ears had no visual references for support. The cilia in my inner ear interpreted a constant motion as no motion. Thus, it was proven to me that spatial disorientation could take place for anyone at any time.
Any quick turn of the head or change in vertical position can stir the inner ear fluids and cause you to fly into an unusual attitude. Once you have allowed yourself to get into an unusual attitude it is important that you believe only your instruments. The turn is the most common source of an unusual attitude. You are most likely to allow any bank to become too steep. The ear and body sensations of a steep turn are G-forces and the instinctive reaction is to pull back. This is contra-indicated. What you should do is first level the wings. Failure to level the wings means that you will soon enter a death spiral at an ever-increasing speed. If you feel such a situation coming on reduce power and dirty up the plane as much as possible with gear and flaps.
A loss of control at low speed is less likely to dismember the aircraft. In any event, level the wings by centering the turn coordinator and ailerons. Any excess speed will cause the nose come up by itself. The first sign of coming through level altitude is a change in airspeed. The nose rising will cause the airspeed to stop increasing. At that point it is time to relax backpressure. Continue to pull back and you will end up in a very steep climb.
A student can get into his own unusual attitude by having the student look down into the cockpit while getting specific information off a chart. After about 20 seconds of this have the student pick something off the floor before going to read and interpret the instruments. Senses are not very good indicators of what the airplane is doing unless confirmed with visual reference.
No More Vertigo
Military has a $15K vest that is electronically hooked to aircraft instrumentation in such a way that sight is no longer needed for flight. Sensor probes in the vest provide continuous orientation information that replaces false information from the central nervous system. Vertical rows of tactors in the vest allow the disorientated pilot to recover in less than 15 seconds from unusual attitudes.
Simulation is not Reality
During the proficiency phase of hood work 'unusual attitudes' should be practiced. This means that you will put on the hood, close his eyes, lower or raise his head while the instructor flies. The instructor will make a series of slow and rapid flight movements designed to disrupt the flow of fluids in the inner ear. After such a series the student will be told to recover the aircraft through use of the instruments. When visual cues are missing the inner ear and kinesthetic systems kick in. When vision is re-admitted confusion occurs. Panic often ensues when an unusual attitude occurs without warning. The unusual attitude instruction must emphasize faith in and use of the instruments, especially the attitude indicator.
If the instructor's efforts succeed, the recovery will be difficult for the student due to sensations of vertigo. Vertigo is a physical condition where the victim suffers symptoms such as spatial disorientation, inability to perform and intellectual confusion. The instinct to trust our senses causes these problems. This instinctive trust must be transferred to reliance on the aircraft instruments through training. Until this transfer is completely accomplished safe IFR flight is not possible. The ability to recognize and recover from a rudder caused unusual attitude is a good skill best acquired through aerobatic instruction.
The recovery from unusual attitudes proceeds through several steps depending on the aircraft attitude and airspeed. If the aircraft/engine noise is high, reduce the power, correct any bank, raise and level the wings on the AI horizon. If the aircraft/engine noise is low, apply full power, correct any bank, lower and level the wings on the AI horizon. Be aware that the instructor may have applied flaps, trim, or covered instruments to make the recovery more difficult.
Knowing how to correctly recover from non-spinning unusual attitudes is important. More aircraft and pilots are lost because they try to pull the yoke to recover a nose-down, semi-inverted unusual attitude than from spins. Use ailerons to roll upright. A non-aerobatic pilot must avoid making the initial reaction which is pulling back on the yoke. More often than not this makes the situation worse. This is specifically true when in a steep bank or inverted. In a spiral, pull the power off, coordinate aileron and rudder to level wings and recover with less than 2 Gs. If wake turbulence puts you into a steep bank or turns you upside down you must first reduce power, move the yoke forward and roll the ailerons to get upright. Any other procedure will over-stress the aircraft.
Unusual attitudes are unintentionally entered by pilots who overestimate their ability and competence while underestimating the weather conditions. Begin by being caught on top of a cloud layer. Follow by a sense of being lost because you no longer have the same sensory aids you are used to having. You can't chart progress except electronically. Instinctively the pilot will turn and fly to where he wants to be, not necessarily where he wants to go.
A private pilot with the minimum required hood time will maintain control about seven seconds on entering IFR conditions. This can be prevented only by getting on the instruments and executing a 180 degree level turn. Failure to act or to act improperly on entering IFR conditions is very likely to destroy the aircraft in the air. Slow up on entering turbulence, keep a light touch on the controls and keep the aircraft level, freely allow altitude changes, and don't attempt any turns.
Below clouds things appear differently, augmented by a desire to keep the surface in sight, the pilot will fly under and around visual obstructions in an ongoing belief that things will get better. They may, but I you haven't checked the weather ahead, they probably won't. You must know which way the weather is moving in relation to your flight direction. It forecasts and winds say the weather is better from whence you came, turn around even though the illusions of improvement ahead exist. Among the disadvantages of flying below the clouds is the instinctive loss of altitude any time you need to improve visibility. Visibility may improve but you are in the process of destroying your ability to communicate. Now a situation that could have been resolved with ATC help is running out of options. As a student this should be a 'hood' exercise with your instructor
Add a dose of air contaminated fuel tanks and an approaching need to descend even further and enter clouds and we need to have pre-planned a few years ago what would be the most appropriate thing to do. Without training and planning, stress will so focus your attention that your recovery will be in doubt. Your arrival on the ground is a certainty. Getting there safely is dependent you how well you exercise mental and aircraft control. We should have worked out these options while a student long before reaching this crisis. Aircraft control is the essential element.
Tumbling Gyros
Readiness to tumble depends on the construction of the gyro. Older gyros have 'stops' that when reached during aerobatics would cause the gyro to tumble and become unusable. This was hard on the instrument so gyros were often 'caged' or locked against moving during extreme maneuvers. Modern gyros are
'non-tumbling' and are not damaged by aerobatics. When a gyro instrument does not behave well after maneuvers or in turbulence it should serve as a warning that it will soon enter a failure mode.
VFR to IFR Options
What to do? If you're on top, do the four C's. Climb, communicate, confess, and comply. If fuel and weather limits your ability to find a VFR escape route. Don't delay, find an area in which to descend to VFR below. ATC vectors may get you to the area but you must know how to make a safe decent. As a student the maneuvers below should be a 'hood' exercise with your instructor. Some practice now may solve a future problem by having a pre-planned solution. Try it until you can do it. When the need for performance occurs you can advise ATC of your ability to perform an IFR climb or descent in a declared emergency.
One way follows. There are other ways. Pay our money and take your choice. Assume that all instruments are functional. Get on a cardinal heading, C.H. power to 2000 rpm, and trim for 60 knots. Let go of the yoke and hold heading with rudder. Slowly decrease power to 1500 rpm and descend at 60 knots using only rudder. If the terrain below is completely unknown as to cloud clearance and terrain elevation. Do the process with full flaps and airspeeds as low as 45 knots. The worse thing you can do is a spiraling descent.
If you are below a cloud deck with a known top attainable by your aircraft and fuel remaining, initiate a VFR to IFR to VFR climb using much the same technique as the descent. Well below the cloud base, initiate a 65-knot climb and trim for hands off. Let go of the yoke and hold a cardinal heading with only the rudder. Once on top you should know if an escape VFR airport is within range.
Hopefully, you will never need an emergency option. You should practice recognition of weather so as to initiate the 180 escape before it cant be done. When the turn is only possible in IFR conditions you must know enough to totally rely on your instruments. Any effort to mix IFR with VFR is doomed to failure. Use the turn coordinator to limit the bank to a standard rate. Better yet learn the amount of bank on the HI that gives the standard rate for your airspeed.
You and Illusions
1) Illusions can and do occur to everyone
2) Proper planning for strange airport conditions is essential
3) Weather and poor visual conditions make airport conditions worse.
4) Rely on your instruments to help your sense perceptions
5) Maintain situational awareness, know where you are.
6) Use airport systems and lights for directional and slope help.
7) Your physical condition can make matters better or worse.
IFR Flying Faults
Initially, VFR to IFR flight results in over-controlling especially when making corrections. Non-instrument rated pilots who fly into instrument weather lose control in about a minute of level flight. The usual VFR movements for climbs, descents, and turns are far too extreme for IFR flight. One technique used to avoid over controlling on heading changes is to use the AI to set the standard rate of turn. Count three, five, or six at a steady rate. Level out from the bank using the attitude indicator top index to level the wings and note the degree of change in the HI. Do this several times until you can get the count needed to get 10 degrees correction every time. Focus on the attitude indicator top index when leveling off. This technique prevents the common fault of reversing the bank back to nearly the original heading. This reversal is caused by the beginner's inability to ignore the turning sense imparted by the fluids of the inner ear. This problem is normal for the beginner but focusing the eyes on the top index of the AI for a few seconds will give the inner ear fluids time to lose their influence.
Vertigo
Beware of false sensations. Your inner ear will give you feelings that are overpowering. With low time under the hood you must avoid attempting to extend maneuvers beyond just holding a heading or a standard rate bank. Any more may exceed your skill capacity for aircraft control in IFR conditions. Any tenseness will cause the inexperienced to over-control. If you have learned to use trim well as a VFR student you may be able to trim successfully for hands-off IFR flight. An aircraft trimmed for hands-off in pitch can be flown in roll (heading) with just rudder input. Descents are controlled by slow power reductions, only.
May cause nystagmus (trembling of the eyes) which makes reading of instruments impossible. Rare but can occur in extremes of weather or flight conditions. Other types of disorientation are illusions such as caused by runway/cloud sizes, shapes, or slope.
Unrecognized spatial disorientation is caused by a combination of a focused attention, distraction and instrument fixation. These most often occur in companion with loss of situational awareness due to excessive work load.
Recognized spatial disorientation is when the pilot is aware of his disorientation. Being aware means that the pilot should be able make his recovery with power and attitude corrections. Pilots have, over the radio, acknowledged their vertigo and inability to overcome it prior to crashing. Spatial disorientation is considered incapacitating when the attitude of the aircraft is so unusual that pilot is unable to determine the cause, organizing the instrument information, and making control decisions.
Vertigo is the #1 cause of Air Force fatal accidents. Vision is the pre-installed vertigo preventative. A moments glance out-the-window is all it takes. This will overcome any sensations from other sources. However, without vision, the organs of balance in the inner ear take over. The semicircular canals approximate the three axes. They contain a fluid that stimulates our senses of angular acceleration in these axes. Our sense of uprightness is done by the otolith organs. Tiny stones affect hair sensors in reaction to "gravity". Otoliths sense linear accelerations, not angular accelerations, and regardless of the direction interpret such accelerations as gravity. In our muscles and joints we have sensors that give additional information about push or pull. Unless one or all of these sensors are confirmed by vision we are on our way to vertigo.
The simulation used for vertigo such as the Barany chair, the yardstick on the nose, etc. in no way prepare the pilot for the real occurrence of vertigo. Unlimited motion in all three axes as well as planetary motion for acceleration are required. Even with these in place it is additionally necessary to create a work overload. The instructor should expose the student to simulations that closely approximate the real thing. That is except for safety of altitude, configuration and airspeed. To train the recovery the same forces and psychological pressures must be recreated over and over by
in-flight simulations.
Illusions
What ever the illusion, it will take a few moments for you to get reoriented. If the illusion occurs in trimmed flight the problem is not as severe as it might be if it occurs during maneuvers as it usually does. Spatial disorientation caused by loss of horizon, change in power, banking, or other acceleration forces can lead the pilot to believe that the aircraft is doing something that it is not. These forces cause the pilot's vestibular and proprioceptive system to give the somatogravic illusion.
A pilots first reaction will be to over-control in a direction exactly the opposite to what should be done. The only safe procedure during the onset of any illusion is to increase your instrument scan rate.
The brain is capable of separating out the conflict of information between the eye and the inner ear when the eyes are looking outside the cockpit. A conflict between the sensory inputs of the body can be overwhelmed when the natural horizon disappears. When the conflict of information comes with the eyes viewing relatively unfamiliar instruments inside the cockpit, the brain can become confused and then give improper information. This is the origin of an illusion. You must trust your instruments in IFR conditions. (See IFR material)
Natural Illusions
Rain
Rain gives the illusion of being higher than you actually are. Combined with haze, you will fly lower approaches during rain.
Visibility
Low visibility can cause the illusion that things are further away. Entering a fog during descent will give an illusion of pitching up.
Wind
An updraft can cause such vertical sensation as to cause the pilot to put the nose of the aircraft down. He senses a climb where the attitude of the aircraft has been level. Avoid the weather conditions that can cause illusions. Believe your instruments. Get an instrument rating.
Health
Illness, medicine, alcohol, fatigue, or hypoxia will make susceptibility to an illusion more likely. It takes very little to cause disorientation
Night Illusions
Runway and approach light illusions will always be a problem if you are in an unfamiliar area. For this reason it is always desirable to make a daylight familiarization flight to an airport before a first time night arrival. Night has its own illusions that are covered in the night flight lessons. The distance of lights is greatly affected by the relative clearness and haze existing. A region of no lights such as might exist off the end of a runway toward the ocean can cause disorientation because of IFR illusions. The best solution is to go on instruments until established inland at altitude.
Variable Visibility
If, while on approach, you should suddenly face reduced visibility you will get an illusion of a sudden pitch up in aircraft attitude. Failing to recognize this illusion will lead to an instinctive and abrupt descent in the approach flight path.
Your ability to determine distance is greatly affected by haze. It is not unusual to call a distance at over twice the actual distance. The sudden appearance of bright lights during an a night approach through haze will create the illusion that the airport is much closer than previously realized. This results in a high approach.
Low
If there is no VASI or VAPI for vertical guidance if you get too low the runway lights will begin to disappear. A steep approach is always better at night. An arrival at an airport with and approach lighting system (ALS) tends to be lower and at a shallower angle than otherwise. Low approach results when runway is approached over dark area. Don't use landing light until close to ground. The visual cues used for a normal night landing seem much the same as you get with a rapid increase in sink rate.
Inverted
If there is a strong crosswind and you are crabbing to the runway instead of slipping you will get the illusion of being inverted. If the airport is well lighted in a surrounding dark area you will have an illusion of being higher than you actually are. Again, a steep approach has much advantage.
High
Rain on the windshield will give the illusion of being higher than you are. If you mistake roadways for runways. It will give illusion of being quite close when lights are bright. High approach results.
Rising
If you are low and pitch the nose up as a correction or through the use of flaps, the illusion will indicate that you are rising. Any reduction of power will cause you to land short.
Diving
At night, banking into or away from a line of lights will give the illusion that a dive or a climb is occurring. The same dive or climb illusion can happen by a change in aircraft pitch occurs while flying toward a light.
A 10 degree bank with only the approach lights visible can cause an illusion that the lights are sloping from above.
Distance
Lights that appear dim, as seen through haze, will be reported as more distant than they are. Example: I once reported an airport as in sight from twelve miles when the tower had me on radar at only five miles.
Landing Illusions
You and every other pilot is susceptible to illusions. when any of our three flight senses (Visual, auditory and Kinesthetic) give erroneous information out mind produces inaccurate information. Flying illusions are most likely to occur at airports due to visual information.
Illusions do not cause accidents. Rather, it is a pilots reaction to the illusion that precipitates an accident. The best way to overcome the negative effects of airport illusions is with experience. Even the most experienced pilot can be fooled.
Our three flying senses fool us by misinterpreting distances, velocity and relationship. Vision is the number one creator of illusion. Over our life time of living and flying we have learned that if two things are of the same size and one appears larger it is nearer. If we know two lines are parallel then when they appear farther apart that is the near end. As we fly we learn an approach slope for our aircraft at our home airport. Our brain has developed a data bank of how things are supposed to be at airports. The terrain around the airport can also be an illusion creating factor. Use all the electronic and visual (VASI) help you can get.
Width
You should practice landings at airports of varying width. All too often you become overly familiar with airports of a consistent length and width. This familiarity interferes with your perception of an airport of different dimension.
A narrow runway can create the illusion of a high approach. The AIM Chapter 8-1-5 states that the pilot who does not recognize this illusion will adjust his perceived approach path to fly lower. Once the pilot realizes that he is low it is vital that full power be applied while maintaining approach speed with yoke pressure. No trim changes. Once the proper glide path has been intercepted the power can again be reduced and the stabilized approach resumed.
The illusion associated with a wide runway causes the risk of flaring rather high above the runway with a hard ground contact to follow.
Visibility
The atmosphere can create illusions. Clear clean air makes everything seem closer. Hazy or smog conditions makes things hard to see and apparently further away. Note: Be aware of this when reporting distances at strange airports. The effect of sunlight in creating shadows is an important part of our visual data bank. At night these shadows are not there. The absence of contrast and background at night is a major cause of night landing and takeoff accidents. Precipitation will distort visibility through the windshield and make to think you are higher than you actually are.
Speed
Our vision is the major source of our cues related to speed. However, much of our speed information comes from our peripheral vision and is often not consciously entered into the brain. The unfamiliar tangential velocity of the ground passing by in a low level bank may appear so fast as to make us pull back on the yoke without regard to the air speed. Stall-spin. This is the classic sequence of the downwind turn from base to final. We have learned to judge both the proximity and speed of a known object crossing in front of us. Closer things seem to move faster.
Expectations
We are all subject to illusion because we have come to expect certain appearances to occur. When we are told to look for traffic, we expect to see that traffic. If we don't see the traffic tension rises; if we see any plane we have our expectation satisfied and we stop looking. We shouldn't. The traffic we see does not have to be the same traffic we should be looking for.
Slope
Gives identical illusion as wide runway but is much more likely to cause the pilot to over-shoot the runway. A runway sloping away will give the illusion that you're low on the approach. A runway that slopes toward you can give the illusion of height. One of the most difficult runways is the one with a mound in the middle. This gives the worst of both illusions.
In landings where you project the possibility of illusions, it is vital that you proceed with the landing using a standard procedure to establish a stabilized approach. The making of predictable changes of power, flaps, and trim becomes very important as the landing progresses. 'Winging' it for changes in these approach elements means that you are subjecting yourself to the effects of illusion. A pilot who fails to recognize illusion is going to make changes as though what he sees is reality.
Any airport that differs from our experience because of runway dimension shape or slope is going to give us an illusion. If a runway slopes away from us our perception (illusion) will be that we are too low. If the runway slopes toward us we will perceive ourselves as being too high. If we react to the illusion we will find ourselves both high and long from the anticipated touchdown point. A wide runway or one whose lights make it appear wider will give the illusion of a low approach causing the pilot to stay too high.
A 3 degree approach to an upslope runway and the illusion is that you are high. The same upslope runway made narrower and you will find yourself low. A down-slope runway creates a "low" illusion which can cause long landings on short runways. I have found the best way to counter airport illusions is to have a constant pattern procedure based on a stabilized airspeed and full flaps. I know that even in the worst conditions of illusion I will be close on final
.
Visual .Deception
Pilots unconsciously make extensive use of their peripheral vision. Level flight, banks, climbs, and descents rely 80% on peripheral vision. (See downwind turns) At low levels our peripheral vision gives us a sense of speed. Over time we develop a peripheral sense as to what "normal" low level speeds are. Add a tailwind, low altitude, a bank to final approach, and a peripheral sense of a "high" speed. We now have an illusion causing a pilot response that says to pull back on the yoke to reduce the speed. The pull merely makes the bank steeper and initiates a low level stall spin. Recovery not possible.
A final approach over high terrain leading to the runway gives an illusion of a low fast approach. An approach over terrain that makes the runway seem like an aircraft carrier will give an illusion of too high and too slow.
Black Hole Landing
When it is very dark you are subject to illusions. Your seat position may make you more or less subject to these. Aircraft seats are situated by a "Design Eye reference Point" (DERP) that is supposed to give a view over the cowl and at the instrument panel. It is not marked on the aircraft but is part of the aircraft design.
If your seat is too low during dark conditions, you will only be able to see runway lights if you are in a descent. The pilot tends to set up a constant angle for their field of view on approach. During daylight, you use the "point on the windshield" to maintain this angle. If the aim point drifts upward you are in an excessive descent; if it drifts downward you are too high. It works the same at night but the references are fewer.
The black hole illusion begins out a few miles on final. The field and lights will be foreshortened. Getting closer the runway should rise in the field of view. If the aircraft is descending the foreshortened view will remain constant. The eye/brain interpretation of this is that the constant foreshortened runway is an indication of a constant angle approach. This is the "everything is fine" illusion of the black hole. During the final phases the daytime depth perception does not work very well.
When flying into a black hole or 'featureless terrain' you must use a correctly set altimeter to counter the illusion. Fly a full pattern using your altimeter and a standardized procedure for a stabilized approach. This is the best way to assure yourself that you will not meet an obstacle on final. This is a combined IFR/VFR approach and requires that you be capable of controlling the aircraft accurately without visual references. The normal order of viewing runway, lights, and dark areas is so changed illusions of being higher occur. If the illusions are believed, touchdown can occur before reaching the runway.
The "black hole illusion" has a dramatic effect on straight in approaches to a runway. The stabilized constant angle approach will appear to exist as an illusion while you fly an arc that flies you into the ground. Do not fly a straight in approach to a runway at night. Know the pattern altitude. Fly somewhat farther out on down wind than appears appropriate. Use a standardized configuration approach just as you would in daytime. Fly the VASI or VAPI if available.
Failure to follow the above recommendations may cause you to make a premature descent. Over flying featureless terrain without lights on an approach that deprives you of the height clues can fly you into the ground.
Aircraft Illusions
There are some optical illusions that relate to nearby aircraft. An aircraft below you will appear to be above you. While getting closer it will appear to descend through your horizon. All the time it is straight and level below you. Avoid the temptation to dive.
IFR for VFR Pilots (Instructor)
The purpose of IFR training is to be able to read, interpret the instruments and fly accordingly. The introduction of the VFR student to the hood should commence with several presumptions. First the student should be reasonably competent in the four basics VFR. This means his banks should be performed at 30 degrees and that trim and power changes can be made to set differing speed and flap conditions. With this foundation the student should be issued some cautions. His VFR control inputs will have to be reduced to obtain the 3 degree per second turn rate required for IFR. The student will have to be made aware that the "pop-up" tendency of the plane when leveling off from turns will be less and of necessity require a different pressure and feel. If VFR instruction has produced a light smooth touch on the controls the addition of a rigid wrist and braced arm will give good IFR control.
The VFR pilot who enters into IFR conditions has an emergency. First off he should declare that emergency on any frequency he can. In actual conditions, just reaching for the radio can cause the inexperienced pilot to lose control of the aircraft.
The human eye cannot determine clouds by size or distance. There are none of the usual references by which we determine size. Beyond 20 feet the one-eyed person is not handicapped except in terms of peripheral vision. There is a fascination in flying in proximity to clouds. Flying toward clouds with the intention of flying over, under, or around can easily lead to flying into them. You will not be aware of the problem until it is too late. When a cloud moves you are too close.
We can normally determine our position and direction of motion by use of the eyes, the inner ear, and the seat of our pants which is called the proprioceptive sense. We use these in conjunction with the gravitational forces of the earth to know where 'down' is when we are on the earth's surface. In the air these senses can be deceived and put into conflict. On water and in the air this can cause motion sickness. A maneuvering aircraft can create gravitational sensations to our muscles and body. Our usual feeling of where 'down' is becomes confused.
The pilot has no option except to learn to ignore these body senses and use only the eyes and aircraft instruments to know what is happening. This ability to ignore and use the eyes is what defines an IFR capable pilot. A slip or skid gives a sense of tilting in the opposite direction. A turn will give a sense of increased gravitational force. This must be visually interpreted as being in a turn through instrument reference and ignored as being going up as in an elevator. The VFR pilot will lose altitude going into a turn and gain altitude coming out of a turn. The body senses want 'level' body pressures to remain constant. This must be ignored and the eyes must be used to enter, hold and leave the turn. Any increase in body pressures is felt as a climb even though it may be a turn. Coming out of a turn is felt as a lowering of pressure or a descent even though it is coming out of a turn. Successful IFR again involves ignoring everything except the eyes interpretation of the aircraft instruments.
Scan (Instructor)
I suggest a scan process of having the student follow my finger as I point successively from HI to AI, VSI to AI, Altimeter to AI, etc. with emphasis upon the AI (attitude indicator). Simulate a change in direction and move the finger faster through the instruments and include the turn coordinator for the standard rate indication. It is important that the student realize that any change in the aircraft direction, altitude, or airspeed requires an increase in scan speed. Any fixation on an instrument such as the heading indicator as it progresses in a turn is to be avoided.
The Other Instruments Scan
---VFR they should be specifically checked at every checkpoint of your
flight route.
---IFR They should be checked more often.
---Other instruments are oil pressure, oil temperature, (fuel pressure),
(cylinder head temperature), exhaust gas temperature and ammeter.
---Deciding if an instrument is faulty or the airplane is faulty is the pilot’s
decision.
---Temperatures are the first indicators of problems
---Air cooled engines are very dependent on the cooling properties of oil.
---Excessive heat is very damaging to an engine.
---Aircraft with fuel pumps are very dependent on the fuel pressure gauge
reading
---Every make and model of gauge has its distinctive failure mode.
---Better scan of the ‘other’ instruments is the hallmark of a superior
pilot.
Hood Lessons (Instructor)
Since hood work is emotionally and mentally tiring it is best to limit each session. Gradually extend the hood time until reaching 20 minute sessions. Vary the time hood work is done during the lessons. New skills should be introduced early, while the student is fresh. Do the new hood work early in the flight for maximum student freshness. Always review the previous before going on. Two sessions may be possible if a good sized VFR break is inserted. On removing the hood it is a good idea to have the student show that he is capable of orienting himself by pointing out landmarks.
Under the hood flying simulated IFR, the student will learn to relate the AI, HI, VSI, turn coordinator, and altimeter to yoke pressures in level flight. The student should be introduced to doing the four basic procedures under the hood. Sometime around the fourth or fifth climb out the student should shown the relative position of the attitude indicator and the nose. He should be placed under the hood and helped maintain the climb attitude, airspeed and heading during airport departures.
Other lessons include transitioning from cruise into slow flight and back again. Reduce power and do descents VFR and IFR. IFR hood climbs and climbing turns can be taught and practiced. It may be best to practice the IFR standard rate turns without the hood and then with the hood. Level off both VFR and IFR. These are fundamental IFR skills that can be practiced and transferred to higher performance aircraft.
For the student to maintain straight and level under the hood that aircraft is initially configured for VFR flight. Then under the hood the student is asked to maintain heading and altitude for one minute. Do this several times with emphasis upon the lightness of pressures required. If the arm and wrist are held rigid and the fingers lightly the one minute of constant heading and altitude can be gradually extended to two or more.
Introduce the hood in climb out and have the student note the wing attitude on the attitude indicator. Have the student attempt left and right 90 degree turns under the hood. Remove the hood and do the standard rate turns without the hood. Then back to hood. Level off under hood and then without hood until the student learns to read the attitude indicator changes as related to aircraft attitude and airspeed. Do both VFR and IFR standard rate turns to headings up to 360 degree turns with stops at cardinal headings.
Did a follow up with pilot trying to give a lesson similar to a pilotage cross-country I read about. Refused to tell pilot what the plan was until we got into the plane. Gave pilot sectional and destination and an altitude limit of 1200 AGL. California is green and colorful in the spring. Even got to look right down into a geothermal turbine.
Flight back was to track VOR radials under the hood. I had pilot talk into tape and intercom so as to give a record of events. Initially I did some coaching about maintaining altitudes and suggested headings both to intercept and maintain radials. Then I pretty much shut up and asked pilot to verbalize corrections. It is not easy to talk about what is wrong, what you are going to do about it and fly at the same time.
Pilot got the plane level at 4,500 and trimmed level. After about five minutes of working on altitude and headings, pilot let go of the yoke. Flew total of 40 minutes under the hood. 20 minutes was in light turbulence with altitudes always within 50 feet and much better with hand off yoke. Moved hands forward and back to make altitude changes. Used rudder only for upwards of 30 minutes to make all heading changes and corrections. Needles strayed out of doughnut only a couple of times. I should do as well. A student's success is instructional victory.
Incidentally, pilot was constantly aware of inner-ear sensations that were contrary to attitude indicator readings. Pilot never had a problem with this until told to look outside for a moment. Going from VFR to IFR and back again is a skill that needs to be taught early in any training program.
Vertigo Simulation (Instructor)
Materials:
1. An open lawn space at least 15' by 15'
2. A yard stick or equivalent light weight stick
Procedure:
1. While standing in middle of open space, have victim hold stick on nose. Hold head as far back as possible and keep eyes focused on upper end of stick. Make several (4-5) 360s at a smooth rate.
2. Stop. Bend down at the hips and while holding the middle of the stick with one hand, place (do not drop) stick in front of you.
3. Remain bent over and step across the stick. Stand up quickly.
Effect:
1. The tilting and turning causes the inner ear canals to receive nerve messages in conflict with the normal axis.
2. The changes in position and movements place the inner ear messages in conflict to the visual messages.
3. When the exercise is done without pauses, the disrupted sense of balance is caused by vertigo.
Practice Illusions (Instructor)
Autokinesis
On a dark night, fly toward a single light. Student is to stare only at the light. After a while the light will appear to move. Student should try to keep the light in one place. Aircraft control will be lost.
Updraft
Have student release yoke and close eyes. Make slow entry into steep bank. Student should tell you that you are in a climb. With eyes closed have student level off. Climbing sensation should cause student to dive aircraft. A real downdraft would cause climb reaction on controls.
Bank
A student is asked to fly with eyes closed. If a bank is entered so slowly that it does not affect the inner ear, any abrupt correction or abrupt movement of the head will cause the pilot to re-enter the slight bank. Since the original bank did not affect the inner ear, the inner ear senses the level condition as being incorrect. Effort of pilot to correct these will only make them worse.
Spiral
A student is told to tip the head and close the eyes. Have student try to hold aircraft level. In a few seconds a gradual bank will occur. Over time, the bank angle will increase. There will be a gradual descent, an increase in airspeed, and an increase in bank angle. If the student pulls back the inner ear senses turning, spinning, or spiraling in a direction away from the bank. Ever increasing wrong control inputs will follow. Effort of pilot to correct will only make things worse. This is known as the graveyard spiral.
Cover the attitude indicator and have student close eyes and lower head to one side. Put aircraft into a shallow constant rate turn for enough time to allow senses to stabilize (360). Have student tilt head up quickly while opening eyes. Done properly student will feel tilted to one side Attempts to correct will be exaggerated in the wrong direction.
Nose up
Have the student enter slow flight eyes closed, without trim , and keep his eyes closed during acceleration and recovery. This causes a somatogravic illusion. The inner ear will sense a nose-up attitude. Deceleration reverses the effect.
Falling Backwards
Have the student enter a climb with eyes closed. After 30 seconds give yoke an abrupt forward movement to slightly nose low attitude while telling student to open eyes. Student will have sense of falling backwards. Further forward pressure only increases the effect. This illusion also has a reverse illusion causing a sensation of falling forward.
Climb
An in flight illusion of climb acceleration by having student close eyes while you fly straight and level at slow flight. Increase speed while maintaining straight and level. Student will have illusion of climb until opened eyes prove otherwise.
Climb-dive
Student eyes closed. From straight and level roll into 45-degree bank for 90-degrees of turn. Student illusion will be of climb until eyes are opened. Do same maneuver but have student open eyes when nearly straight and level. Student illusion will be that aircraft is diving. Wing-level skids with eyes closed gives tilted sensation. Steep half Dutch-roll will cause student to sense bank in opposite direction.
Falling
Have student close eyes and move head forward and down in 20-degree stages. Enter coordinated 30+-degree bank. Have student turn head quickly and just as quickly bring head up. Time roll recovery to coincide with heads up. Illusion is falling to direction of roll.
Lowering Clouds:
At 2000' and under the hood have student note the time and after one minute descend 500', after two more minutes initiate another 500' descent, after 4 minutes descend still another 500', advise that after 8 minutes he will need to descend 500' more. You are looking for the student to make a decision to turn back or land.
Icing:
At level cruise and under the hood. Advise the student that after initial application of C.H. the power will be reduced 1-200 rpm every minute by the instructor. The student is to make a decision as how to proceed.
(Climb while able, descend to warm air, land.)
False Horizon
Eyes closed under hood. On a dark and hazy night fly diagonally across a freeway where other lights are infrequent. Problem can be made worse by angled road lights or light patterns. Angle of lights could cause student to react with dangerous flight attitude. Pilot thinks horizon is out of level and attempts to align with illusion. In IFR conditions this will occur as you break out below a solid cloud ceiling.
Eyes Closed or under hood. On a dark and hazy night fly diagonally across a freeway where other lights are infrequent. Light pattern could pilot to react with dangerous flight attitude.
Elevator Illusion
Caused by quick upward acceleration as in updraft. Climbing sensation causes dive reaction. Could be caused by downdraft which results in climb reaction on controls.
Eyes closed. Make 90-degree turn with very slow bank entry from level into a 50-degree bank attitude. Student should have illusion of a climb. This same illusion can occur when caught in updraft. A sudden downdraft can give illusion of dive even though aircraft remains in level attitude.
Coriolis Illusion
Caused by abrupt head movement during a constant rate turn that has existed long enough to stabilize the inner ear. Gives sensation of motion on another axis. Attempts to correct
Eyes closed, head down and tilted (Cover AI). Enter extended constant rate turn until student no longer senses turn and bank. Have student make sudden head movement to instruments and open eyes. Student should sense rotation on another axis. May react to dangerous flight attitude.
Inversion Illusion
Caused by abrupt change from climb to level flight. The pilot senses that he is falling backwards. The instinctive response of lowering the nose only makes the sensation worse.
Eyes closed. Have pilot enter and trim for climb. When senses have had settled, have student push yoke forward to nose low attitude while opening eyes. The pilot should sense feeling of going over backwards.
Leans
Eyes closed. Enter a bank so slowly that it might not trigger the inner ear motion senses. Once into the bank, make an abrupt correction. The student will react to his mistaken senses then by re-entering the previously created bank and will remain there.
Lighting Illusions
Pilot mistakes roadways for runways. Give illusion of being quite close when lights are bright. High approach results. Low approach results when runway is approached over dark area. Don't use landing light until close to ground. The visual cues used for a normal night landing seem much the same as you get with a rapid increase in sink rate.
Instructional Use of MS Flight
Simulator
To answer your question I will need to tell you a 'war-story' At the end of WWII I was 21 years old. I had worked for about nine months as a LORAN instructor and then as the operator of a bombing simulator for the use of B-29 crews. When the Japanese surrendered, I had to wait my turn for the ride back to the U.S. Those who wished could go back on a B-29 but military planes are not as safe as they might be. I chose to wait for a ship.
In the barn like Quonset building next to mine there were eight flight simulators. These were the only types in the world at that time called 'Link trainers". The Link looked like a stubby wing airplane about 8' long and 8' of wing. The cockpit had a cover that would close and put you in a cockpit with only instrument lights.
The controls and instruments of the Link were based on the twin engine DC-3. With nothing to do for nearly two months except sit in and fly the Link I became quite capable of flying the Radio Range system into McCelland Field near Sacraments, CA.
Twenty-one years later I took up flying lessons at Concord, CA. Because of my prior experience in instrument flying, I had a terrible time, initially,
learning to fly. I did not know how to look out of the airplane or even what to look for. I had to un-learn my concept of flying and learn another one.
On the other hand, when it came to night and hood work I could fly quite well because of my hood experience. To answer your question, yes the simulator will be of benefit but not where you expect. The simulator time will make it necessary for you to mentally reject the instruments and learn to look outside.
My telling you this and your accepting it, will make your learning to fly come easier but not as easy as it would be if you had spent the time reading "Stick and Rudder", Ron Machado's book or even running through my web site.
Expecting Illusions
Only by knowing where and when illusions occur can the pilot expect to anticipate their occurrence and focus on
the instruments. The runway length and width proportions can cause a high or low illusion. Wide, short and down slope runways give low illusion. Long, narrow and up slope runways give high illusion. Haze and mist makes runway seem farther away. Bright lighting makes it appear closer than it is. Rain during the day makes runway appear farther away.
When taking off in a black hole situation the acceleration, rotation and nose up attitude during initial climb can cause a somatogravic illusion. You will feel that the seat is being tilted back. The sensation is that there has been a shift in gravitational pull. This causes an instinctive reaction to lower the nose of the aircraft to counter the kinesthetic sensed pitching up illusion. The power of this illusion is so strong that only a determined concentration on the attitude indicator can overcome the illusion.
Another illusion is that of being higher than you are when on an approach to a runway. This illusion is common for naval pilots approaching carriers. Even though all instrument readings show on glide slope, the visual picture is one of being very high. Rain on the windshield can cause the same illusion. This 'being high' illusion is the main one that makes night flying different than day flying.
Recovery from VFR into IFR
--Reduce power
--Full flaps
--Full nose up trim
--Hold heading with rudder applications based on turn coordinator indications.
VFR into IFR
--The pilot wants to get into the air and see if he can make it.
--When he is forced into the go/no-go decision the retreat is just as bad as the forward potential.
--The decision is all the more difficult if the pilot has 'got away with it' before.
Night Light Illusion
I have found that the landing light used when there is sufficient moisture
in the air to make the light beam visible can have a negative effect on your
ability to make the proper round-out and flare in the landing. The
Illusion will make you flare too high.
Item:
In the distant past I have had the tower use its light gun to show me the taxi
line. Helped, worked.
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