Discuss the problems and solutions to all of the situations that Pilot X finds himself in.
By Echo Delta
#1075948
Display in the Blood

Nick Barnard introduces us to a pilot who loved the surge of raw power, yet was eager to avoid mishaps…

Pilot X was a fast learner, and good at detail, which is not a bad combination when it comes to a Yak-52. He soon understood that this is the ultimate gotcha machine for the unwary and the cavalier, and he was eager to understand how to avoid mishaps. And they’re certainly waiting for you.
Pilot X loved all the challenges, and more. The Yak is a military trainer, and he revelled in the heritage behind the design, and the demands it placed on his management skill and ability.
As for the flying, Pilot X was a safe pair of hands. He soon learnt to master the general handling and he also relished the added thrill every time he flew with a military pilot, as they always surprised and delighted him with an impromptu display. His training included spinning… and even inverted flat spinning, which gave him a manly dose of bloodshot eyeballs. But this training was, of course, from a safe height, at over 6,000ft and he always practised with an experienced pilot.
Little by little, Pilot X grew into his flying suit. He mastered the eccentricities of this powerful Russian beauty, and looked forward to each new challenge, beginning to feel a gentle surge of confidence every time he pushed his boundaries and survived.
He wanted more thrills, and the Yak delivered. Guided enthusiastically by his group, Pilot X explored basic aerobatics, and he never forgot a teasing introduction into the art of formation flying. Waiting his turn to fly, Pilot X sat and watched his military friends practise aerobatics in the overhead, drawing an excited crowd of spectators who gasped as the Yak looped and rolled, roared vertically upwards, hesitated, swung about on its axis and dived earthwards, whistling and throbbing with power and energy.
Pilot X worked hard to expand his aerobatic repertoire over the airfield, excited by the prospect of being the centre of attention.
Taking up passengers compounded his resolve. Pilot X loved their shrieks and screams as he tore through the air, rolling and looping over their homes, or over the sea, and best of all, over the airfield.
Sometimes, the Yak snatched a bit when he pulled too hard in a loop − and when he was a bit low and slow and needed 100% power, he was surprised at the change in the character of the Yak – he was overwhelmed by the increased torque, and couldn’t quite keep up with machine, so he stayed away from practising this more extreme flying. At other times his stall turns were rather uncomfortable, but at more than 3,000ft above the ground, he was confident that he could recover from a mishap.

Exclusive club
Pilot X found himself drawn closer and closer to the ground, failing to realise that at 2,000ft you’re only one-third of a mile up. But boy, was it thrilling!
Each flight, or sortie, he embellished his show with a selection of crowd-pleasing touches. He realised that what he really wanted was to be a display pilot, and when one of his pilot friends – a military-trained display pilot of course – commented on the spectators’ excited reaction to his antics in the overhead, he knew he was not far off joining this most exclusive of clubs.
Not long after, there came a classic early summer, peachy day, with unlimited visibility and a scattering of small and docile puffy clouds. Pilot X felt good – he was off to the coast to fly over a seaside caravan park, where some camping friends were expecting some aerial entertainment. As he filled the wing tanks, a group of visiting pilots were admiring the Yak, full of questions. Still chatting, Pilot X secured the tank covers with his little screwdriver and then leapt up onto the wing and stepped into the cockpit.
Loving the surge of raw power, Pilot X pushed the throttle wide open and, quick as an ace, he was airborne, retracting the wheels, urging the heavy 52 to accelerate, keeping the nose down as low as he dared. Approaching the boundary, he pulled back sharply, and the crowd “ooooed” as he soared skywards at a crazy angle.
Slowing quickly, Pilot X pushed forward a touch and rolled left, but out of balance, and as he pulled smartly out from his shallow wingover, the airframe gave a little shudder. He zoomed low across the edge of the airfield, past the café, and then departed for the coast nearby, waggling his wings as he went.
It was a perfect display venue, sloping down to the sea, with a 150ft cliff edge, and no trees or obstructions. The visibility seawards was not ideal, as the horizon and the ocean merged indistinctly in a layer of morning mist.
At about 1,750ft he started his dive towards the ocean and then, at 200ft, pulled up and climbed vertically.
From the caravan park the witnesses noticed that he was not quite vertical and that the engine seemed louder than usual. It was also evident that he was left-wing-low and even a touch negative (on his back).
To Pilot X it was becoming a little confusing. The Yak wasn’t doing what he expected. Nevertheless, as it slowed he applied full rudder, but rather than pivoting nose down in a stall turn, the aeroplane shook, seemed to pause, almost fluttering in the sky and, in an instant, was on its back, and rotating, fast.
Moments later, without showing any signs of recovery, the Yak span into the sea.

Questions
1 Apart from disorientation and loss of control, what were the other possible main factors contributing to the accident?
2 What particular challenges did Pilot X face by starting his display over the sea?
3 What possible reasons were there for why the aircraft showed no signs of recovery?
4 What could Pilot X have done when things started to go wrong?
User avatar
By kanga
#1076052
simplistic response ..

recalling an earlier incident: had his 'little screwdriver' dropped out of a pocket (which, distracted by admirers, he'd failed to fasten properly), and eventually arrived in the rear fuselage where it had fouled or jammed a control cable ?
Last edited by kanga on Fri Jun 22, 2012 5:42 pm, edited 1 time in total.
#1076804
1. Pilot X seems to be operating in the area where coarse control inputs can cause the AoA to approach the stall -"Sometimes, the Yak snatched a bit when he pulled too hard in a loop... as he pulled smartly out from his shallow wingover, the airframe gave a little shudder..." the Yak was probably already stalled in the vertical climb - which is why it was not responding to control inputs as usual "The Yak wasn’t doing what he expected" and when he applied rudder this provoked a spin entry. The application of lots of throttle also generates extra lift and thus increases the AoA further, possibly to or past the point of stalling. Poor awareness of the symptoms of the approaching stall in this aircraft owing to insufficient practice.

2. "The visibility seawards was not ideal, as the horizon and the ocean merged indistinctly in a layer of morning mist" Lack of visual references. When I used to fly glider aerobatics, the horizon was the primary source of reference against which the orientation of the aircraft could be judged.

3. Incorrect stall/spin recovery - the pilot probably didn't know the wing was stalled. Could have been apprehensive once things started to go wrong "couldn’t quite keep up with machine, so he stayed away from practising this more extreme flying..." indicates someone not really comfortable operating in this part of the envelope so probably lacked any deep familiarity with the symptoms of the approaching stall - see 1 above...In the inverted spin, it can be hard to tell which way the aircraft is yawing. Also the requirement to pull the stick back instead of pushing could be difficult to recall in a state of panic.

4. Centralise the controls and work out what's what. I might be quite tempted to bail out, as well.....

Just my 10p worth....
By zlhglp
#1078375
1 Apart from disorientation and loss of control, what were the other possible main factors contributing to the accident?

Overconfidence appears to be a major feature. He'd previously aimed to recover by 2000 feet. Here, he's entering hammerhead turns from 200 feet, and in a new environment with few visual cues to altitude. He also performed a zoom climb that probably would not have been recoverable in the event of an engine failure.

There's also a lot of pressure on him, which may have affected his judgement. The five most dangerous words in the English language are said to be 'hey everybody, look at me!' This was apparent on two occasions: firstly when he was doing his checks with an admiring audience, when he may have been distracted. Secondly, in continuing with his display even though he had several indications that the aircraft was not handling as he had expected. If he had not scheduled a display, he may have done the sensible thing and returned to base.

My feeling is that there was something wrong with the aircraft that he did not pick up on his distracted preflight. This caused the handling to change. I once had an experience where I accidentally selected the alternate static source. This caused the airspeed to read 10 kts higher than it should. A similar issue or leak in the static system could have led Pilot X to fly his manoeuvres slower than placarded, which could have caused the buffet and in particular running out of speed in the stall turn.

2 What particular challenges did Pilot X face by starting his display over the sea?

Aside from the fishbowl effect making it hard to identify the horizon, the sea provides few visual cues to altitude and this could have been important when judging pullouts. It could be that Pilot X thought that he was starting his hammerhead turn from a much higher altitude than was actually the case.

A side issue may be that bailing out over the sea is much riskier than doing so over land. Most paraglider pilots who land in the sea, drown. This could have made him reluctant to do so.

3 What possible reasons were there for why the aircraft showed no signs of recovery?

The pilot may have been utterly disoriented, and applied pro-spin controls or not attempted spin recovery at all. There's no mention of him cutting the engine, so perhaps he still had power applied. It's also possible that he had suffered a failure of the control surfaces preventing him from recovering. This could have explained the unexpected flying characteristics. It's also important to hold onto the stick and pedals tightly during a tailslide, as the rudder surfaces in particular can be slammed against the stops and damaged.

Pilot X may also have suffered from benign paroxysmal positional vertigo, which can be quite incapacitating. A backflip is one maneuver that can certainly set it off. Personally I only suffer from it in one specific head movement, and have never had any trouble during aerobatics appreciation. I suspect it's possible to become quite an accomplished aerobatics pilot before 'discovering' it as a phenomenon.

4 What could Pilot X have done when things started to go wrong?

He should have abandoned his plans to do a hammerhead and done a backflip with no rudder applied, allowing the speed to increase to a safe level before pulling out. With a hammerhead or "stall turn", no stall is involved so there is little chance of entering a spin and it is safe to maintain rudder despite the slow airspeed. In contrast, in a backflip the wing does transiently have a significant angle of attack and therefore it is possible to enter a spin if rudder is still applied.

He could have attempted a spin recovery - either he did not have time or perhaps froze at the controls. Many pilots who can perform planned spins reliably, do not recover correctly from unplanned spins.

And of course, he could have bailed out if he had sufficient altitude.