My night flying instructor, Diamond Dick, was a rough bastard who flew a Bonanza for De Beers. He seemed to spend much of his time assisting the police with their enquiries into the disappearance of pebbles.
Dick did the dual part of my night training in ZS-DXG, a 235 Cherokee.
It consisted of two landings on two-zero at Kimberley, in South Africa, done in the ochre afterglow of a desert sunset.
He then bought me coffee in the terminal building, told me not to bend the aircraft and sent me off to do the required five solo circuits and bumps. Briefings were not a huge part of Dick’s curriculum.
At the time I had 290 hours, of which three were under the hood.
By now it was completely dark so I did the pre-flight with a torch and took off on two-zero again – away from the city lights, and climbed into a black hole.
Things soon started to feel strange.
I leant forward to see if I could spot some landmark or light through the inky windscreen – there was nothing. The wind noise sounded different. A glance at the ASI told me that my speed was increasing.
I eased back on the stick and looked behind the left wing for the lights of the terminal building. Nothing – blackness everywhere.
Then the airspeed started running away again so I pulled harder on the stick. It didn’t seem to make much difference. Something was very wrong and I knew the ground was getting closer. The cold grip of panic started to rise in my chest.
I looked frantically for some reference. Then I saw the terminal building lights at a ridiculous angle slipping sideways off the top of the windscreen.
I levelled the wings and got the nose up just in time to glimpse a dull red glow under the left wingtip where the nav light lit up the desert scrub a few feet away.
The city lights gave me a usable horizon and I found my way back into the circuit with my heart pounding.
Either pride or stupidity caused me to continue flying and do the required five solo landings. Each takeoff was followed by a sweaty-fisted climb and crosswind turn in the blackness with my eyes stuck to the AH. Diamond Dick had never suggested this procedure – I invented it that night.
What happened to me is something that has killed thousands of pilots – including John F. Kennedy Jr. I entered a graveyard spiral.
“OK,” you say, “What’s the big deal? You lost control because you weren’t looking at the AH. Now you know what to do – just keep your eye on the instruments and get over yourself.”
Hmmm. If only it were that simple.
Beware – your senses are lying
Some years ago, my daughter Margie was an SAA Boeing 737 co-pilot. She told me that they were doing a right-hand turn out of Johannesburg one night. She allowed her attention to wander for a moment but was soon snapped back to reality when the Captain said calmly, “Let’s try and keep it shiny side up shall we, number two?”.
She was mortified to see the attitude indicator showing a bank angle approaching 60°.
How can this happen? How can a well-trained and current, instrument-rated pilot lose control of a serviceable aircraft without even knowing she is in trouble?
The answer is that when you lose sight of the horizon you are left with three other senses that all lie to you. We will look at these in a minute, but if you take the horizon away from a pilot, or even a bird, you have a floundering creature that has no idea where the world is.
Yes, I know you think you could tell where down is – believe me, even you can’t do it!
To illustrate this let me introduce Armpit Edwards, a pupil I had in Port Elizabeth. He was a malodorous little Lancashire man with a dedicated resolve not to waste flying money on soap. I was subjected to the full impact of this commitment every time he reached for the overhead trim handle in the sweaty confines of my little Piper Colt.
Anyhow, I was at the blackboard explaining the no-horizon problem when Armpit stood up and told the class I was talking bull – he would always know where down was.
I didn’t charge him for his next flight, which involved a short period in cloud, during which it took him less than a minute to enter a graveyard spiral and start yelping for help.
At the following lecture Armpit had the grace to point his thumb at me and inform the gathering, “Ee’s bluddy right, ya know”.
It’s easy to see where Armpit was coming from. You can shut you eyes and point where down is. This is because you have two gravity pointers. Your muscular reactions to G – your butt and leg muscles can feel where your weight is. And the utricle in your inner ear, which is like a dish with peas in it. Sense hairs in the dish tell you where the peas are sitting.
So that’s it. On the ground you have three up and down detectors – your eyes, your muscles, and the peas in a dish.
Now watch in horror as all three of these senses betray you in flight.
The first to go is your visual reference – it doesn’t work in cloud. You have no horizon or verticals to tell you where down is.
Next, your muscles become fooled by the aircraft’s motion. We know that when you are sitting, down is beneath your seat. But what happens if we do a loop? Well, it’s like swinging a bucket of water over your head – when the bucket is upside-down the water stays where it belongs. It thinks that the bottom of the bucket is down because that is where it is being pushed by centrifugal force (apparent G).
The same happens to you at the top of a loop – you are held in your seat. You feel that down is below your butt – which is actually up.
Okay, so we don’t all do loops. But a turn is equally deceptive. Your muscles have no idea that you are banked because the G of the turn pushes you squarely into your seat. Your muscles feel apparent gravity – not actual gravity. They think that down is the place where your gold watch would hang if you suspended it from its chain.
But there’s another complication. In a nose-up attitude some of your weight rests on your back so you correctly sense that down is somewhere behind you. But you get exactly the same sensation if you accelerate – you also feel pressure on your back. In fact there is no way you can tell the difference between a nose up attitude and acceleration.
Airline simulators work this way. When you move the thrust levers forward for takeoff, the simmy tips back and you feel this as acceleration. When you use the toe-brakes, the simmy leans forward and you feel as if you are being pushed towards the windscreen by the deceleration, but it’s actually gravity.
The peas in a bowl act as a backup to what your muscles tell you. If you lean back, the peas roll towards the back of your head. And if you accelerate the peas also roll towards the back of your head – they sense the same thing – apparent gravity. And in doing so they confirm the lies that your muscles tell you.
This means that when you enter cloud, or fly on a black night, not only do you lose all sense of up and down, but two of your life-long, trusted sources of information actually combine to tell you identical lies.
But wait, there’s more
But that’s not the worst of it. The inner ear contains another mechanism that causes dizziness, motion sickness and vertigo – the semicircular canals. These are three little liquid-filled tubes with sense-hairs in them. They tell you about your movement in the pitching, yawing and rolling of planes. Imagine them as inner tubes from car tyres. One lies flat, one is fore and aft in your head and the other is crossways.
Let’s look at the one that lies flat – it tells you about yawing. Picture a liquid-filled car tube lying flat on a secretary’s swivel chair. Now we start turning the chair around to the left – anti-clockwise. The liquid in the tube gets left behind, and if there were sense hairs they would detect this movement, and send a message to say, ‘We are turning left’.
That’s great, but if we keep turning left the liquid soon catches up with the tube and the sense-hairs detect no relative movement so they signal, incorrectly, that you have stopped turning.
Now, if you do stop turning, the liquid surges on for a while and sends lies to say you are turning right.
This is what happens when you make yourself giddy by turning round and round. When you stop, the liquid in your semicircular canals keeps moving and tells your brain that you are turning the other way. Of course, your eyes say you are not turning, so you stagger and fall about while your brain flounders with conflicting messages.
For pilots, this clash of information causes vertigo – a condition which can vary between a mild case of the leans (which every instrument pilot gets) – and full-on vertigo, which is dizziness that can be accompanied by a sensation of tumbling backwards and possible vomiting. Complete incapacitation.
So the semicircular canals frequently lie about what’s happening in all three planes of motion.
That’s the physics of it. When you fly into cloud you lose your most trusted reference – your visual information about up and down. And you are left with three liars – your muscles, the peas and the semicircular canals.
To fly safely on instruments you must learn not to trust any of these senses that are hard-wired into your soul. Then you have to bet your life on instruments that you know can fail. Once you have mastered this you need to keep practicing – forever.
Lay off for a few months and you will find all over again how easy it is to lose control.
Instrument flying is not like learning to swim or learning to ride a bike – you forget it very quickly.
Avoiding graveyard spirals
Now let’s see how a graveyard spiral happens, as it is the standard way of losing control.
You enter cloud with the aircraft trimmed and the wings level. After a little while a wing drops slightly due to turbulence, fuel imbalance, the rudder being slightly out, or whatever.
You don’t notice the bank because your senses lie to you, but you do hear an increase in revs and wind noise as the bank causes a slight loss of lift and a nose down attitude.
No sweat, you correct the problem by gently easing back on the stick. But what you have really done is to tighten the turn, so this is followed by a further dropping of the nose and another increase in speed and revs. This calls for more back pressure, which causes a tighter turn and a further loss of lift – and so on.
Soon your entire being is focussed on pulling back to prevent the terrifying loss of height and the runaway airspeed. Ultimately you will either pull the wings off or sail into the ground. That is exactly what happened to John F. Kennedy Jr and his two passengers.
A non-instrument pilot normally enters a graveyard spiral within about 120 seconds of losing the horizon.
Sounds silly I know – particularly when you know it can happen, and you know it can be remedied by levelling the wings. But silly or not, it has killed thousands of pilots who thought they could handle it. They focus their entire being on arresting the descent – everything else is secondary.
I know, Diamond Dick gave me the T-shirt.
So how do you make sure it never happens to you? Keep away from clouds and black nights until you have a properly equipped aircraft, an instrument rating – and are current. Full stop.
For anyone who is still not convinced, here are the FAA’s chilling words on the final 35 seconds of John F. Kennedy Jr’s life. Remember as you read it that he had passed the Instrument Rating exams and had 39 hours of instrument training:
“As the airplane bank angle increased, the rate of descent increased, and the airspeed started to increase. By 2140:25, the bank angle exceeded 45°, the vertical acceleration was 1.2 Gs, the airspeed increased through 180 knots, and the flightpath angle was close to 5° airplane nose down. After 2140:25, the airplane’s airspeed, vertical acceleration, bank, and dive angle continued to increase, and the right turn tightened until water impact, about 2141.”
Jim Davis has 15,000 hours of immensely varied flying experience,
including 10,000 hours civil and military flying instruction. He is an
established author, his current projects being an instructors’ manual
and a collection of Air Accident analyses, called Choose Not To Crash. Visit Jim's website by clicking here.
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