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 carburettor 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.

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.

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 manoeuvres 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 spiralling 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 levelling 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 manoeuvres 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 manoeuvres 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. 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.

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.

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.