CGC - What went wong

What went wrong

31-Aug-11

The incident described in the following article from 2000 attests to the critical importance of student pilots, pilots, instructors and passengers being acutely aware of (and understanding why) they MUST NOT unfasten safety harnesses in gliders while in the air ...

WHAT WENT WRONG

FLIGHT SAFETY AUSTRALIA, MAY-JUNE 2000

The man who fell to earth

Geoff Osborne

It was like a scene from a B-grade Hollywood comedy: a glider pilot finds himself lying face-down on a perspex canopy wondering if it will stop him falling thousands of feet to the earth below. It doesn’t

IT WAS the first day in ages that offered any real potential for soaring. Thermal activity was strong and I had little trouble reaching 3,500ft on my first climb in the single-seat Cirrus.

The aim of this flight was to fine tune a recently purchased Balsak computer speed director, which requires minor in-flight adjustments after installation via half a dozen tiny trim pots located at the base of the unit.

I began my tests, accelerating to 100kt, gently raising the nose and closely watching the result on the instrument. The wide spacing between the thermals made the task easy. After four or five tests I was getting a little low, so I found a thermal and – while climbing in the lift – made an adjustment to the trim pot on the instrument using a small fine-blade screw driver.

As we approached the top of the thermal at 4,500ft, the screwdriver slipped from my fingers, fell to the floor and rolled back under the front part of the seat, just out of reach. I began to run through the possible problems the loose screwdriver may cause. I knew that just behind a small bulkhead, under the seat, were the elevator and aileron control rods. As long as the wayward tool remained in the bottom of the aircraft, in front of the small bulkhead there would be no problem.

If, however, the screwdriver made it to the other side of the bulkhead, it could easily become lodged in any number of open fittings and bearings and could cause the elevator or aileron to become jammed. I started the descent, heading back toward the airfield, five kilometres away.

" I shot upward and ended up with my face pressed hard against the thin perspex canopy. For a second or two it held, then exploded with a huge bang sending sharp jagged triangles of plastic flying in all directions. "

At 3,000ft cruising at 50kt I hit a rough patch of turbulence and the aircraft zoomed, then fell. Below the seat the screwdriver clanked, then after another dip I heard a metallic clang which I could feel through the control column. It must have passed through one of the holes in the bulkhead. I gave the controls a wiggle, and felt no obstruction. Reassured, I decided all was well. But then I began to think about the possibility of turbulence while on final: if the controls jammed I wouldn’t have the height to recover.

Loosening the shoulder harness I lent forward and reached under the seat. I could feel the screwdriver with the tips of my fingers but couldn’t stretch far enough to grab it. I loosened the seat harness as far as it would go and unlocked the rudder pedals sliding them all the way forward. I then slid as far forward in the seat as I could go. The screwdriver was still beyond my grasp. I would just have to chance the landing.

At 2,700ft I ran into a turbulent thermal, and the screwdriver was once again clanging below the seat. I could feel the slight impact through the control stick. Images passed through my mind of the Cirrus stalling or spiraling in, completely out of control on short final. I had to get that screwdriver.

A few careful turns in the thermal and I was soon back at 3,000ft. I set the heading for a large blue hole, thinking there would be less turbulence out there. With the harness loosened I leveled the wings, set the trim for 45kt and slid forward again. Reaching under the seat with my right hand, I managed to slip it through the bulkhead.

The screwdriver now lay in the bottom of the fuselage well out of reach. I slid back in the seat to plan my next move. Opening the airbrakes and lowering the nose I could hear the screwdriver slide forward as the aircraft decelerated, then a “thunk” as it hit the back of the forward bulkhead and stopped. I was hoping this would place it within reach. I slid forward again and, holding myself in place with the pressure of my legs, I gained access through a hole and managed to touch the driver with the back of my hand – but from my position it was impossible to pick it up. Adding to the problem was the size of the access hole, making it impossible to rotate my hand and grasp the little sucker.

I simply couldn’t slide forward enough to grasp the screwdriver while wearing the harness. So checking the area, I headed for a large blue patch about five kilometres wide directly in front.

Hit by a strong thermal: Undoing the harness completely I slid all the way forward. This allowed me free access to the bulkhead and I could now rotate my hand about 90 degrees as it entered the hole. After fumbling a little, my fingers managed to trap the loose screw driver against the back of the bulkhead as I quickly worked my fingers till I had it in my grasp, mission accomplished.

Arching a little in the confines of the cockpit and supporting myself on one elbow I retrieved one side of the harness. Leaning the other way I easily retrieved the other half. With both the lower parts of the harness now in my grasp I wiggled in the seat, at the same time pulling both ends free, preparing to snap them into the locking mechanism.

Hands on the controls: The Cirrus is quite marginal in terms of pitch stability and has an all-moving tailplane which is powerful in effect and very sensitive at high speeds. Two good reasons for leaving at least one hand firmly planted on the controls at all times.

Suddenly the glider hit a strong thermal hidden in the blue sky and the left wing rose rapidly. At the same time the nose swung to the right and dropped, placing me in negative-g. Fortunately I was holding the end of the harness straps together, and this stopped me from being thrown out. As I attempted to slide the ends into the snap clasp, the glider continued accelerating with the nose down at about 30 degrees, with a slow roll to the right. The negative-g increased along with the speed. It required a great effort to hold on to the two ends of the harness – the only thing preventing me from being thrown against the perspex canopy. I managed to slide my left leg out from under the instrument panel and place my heel on the other side of the control stick. I was travelling well over 140kt and still in negative-g but the pressure required to hold on was easing noticeably. I felt that I was beginning to get the aircraft under control again. I tried to put more pressure on the stick, but my foot suddenly slipped from behind the stick. The trim control took over again, the stick shot forward, and the glider was suddenly in a 20- degree nose down attitude with about 60 degrees of right bank. The nose suddenly dove past the vertical, and the aircraft rolled upside down.

The sudden increase in negative-g finally broke my hold on the harness. I shot upward and ended up with my face pressed hard against the thin perspex canopy. For a second or two, it held, then seemed to explode with a huge bang sending sharp jagged triangles of plastic flying in all directions. I became a projectile.

All I could see were blurred coloured streaks, of green, brown and blue. It took a moment before I realised my loss of sight was caused by the speed I was now travelling.

I seemed to be on my back, looking up at the blurred blue streaks. But what height was I at? I started at 3,000ft, minus the time spent on the initial dive, plus the time spent on the second descent. Two and a half thousand feet seemed a good guess, minus the time spent laying against the canopy, and the distance I’d already fallen. Somewhere between 2,200 and 1,100ft I guessed. Did I have a parachute? I was going to leave it behind – I normally only use it as ballast – but I did bring it.

Five seconds passed. It was time to pull the cord. In my mind I was looking at the parachute as though I was standing in front of it studying it. I could see the “D” ring tucked in its pouch on the right side. I found myself looking at my right side – it wasn’t there. I suddenly realised it was on the left. My right hand darted across my chest and pulled the “D” ring.

A green flash raced past my right side moving at high speed – the pilot chute, instantly followed by a long green streamer as the main canopy raced out of the pack after it. An almighty “FRUMP” and suddenly I was decelerating from 120kt-plus, to something more moderate as the large 28ft canopy deployed.

Crippled aircraft:

Directly above the parachute, like a moon peering out from behind a cloud, the inverted glider appeared – large and close. I watched closely as the crippled aircraft circled off to the right. It was descending at a faster rate than me and its orbit appeared to be centred on me.

A glider with a grudge! I watched it slowly circle toward me approaching from the left, just 20 metres away and slightly above. The approach angle began to look threatening. I grabbed a handful of lines at the rear of the chute, pulled them down to my waist, hoping this would steer me inside the glider’s turn. I watched closely as it passed a few metres below my feet then collided with the ground, breaking the left wing in two, and snapping the rear of the fuselage at the base of the fin, sending up a small cloud of dust.

Suddenly I realised I was only a few feet off the ground. This was my first parachute jump, so I flexed my legs, bending them at the knees in preparation for the hard impact of the landing.

I found myself standing upright on the ground – no impact, no sliding along. I remember wondering whether I should do a roll or something. A trace of blood was running down the outside of my nose. My sunglasses must have cut me when they were trapped between my face and the canopy.

As I unclipped the parachute, I noticed that I still had the screwdriver clutched tightly in my hand. It took almost a month for the scarlet red marks on my body left by the parachute harness to fade. Several ground observers of the incident judged I had deployed the parachute at about 800ft.

Broken hull: VH-GOT after it plummeted 3,000ft to the ground without a pilot. After an extensive rebuild, the aircraft came 11th in the nationals later that year. The aircraft is still flying today.

ANALYSIS > Before a fall

Maurie Bradney & Mike Valentine

Maurie Bradney is the Australian national gliding coach.

Mike Valentines is a CASA sport aviation specialist.

IF YOU fly an aircraft in which it is normal to wear a parachute (most single-seat gliders) and if in fact you have a serviceable parachute with you, wear it – don’t just use it as a cushion. Geoff very nearly did just that, and he would have paid the highest possible price had he not come to his senses before take-off and strapped it on. It was a recently repacked chute, so it opened correctly and he got a complete canopy

While it may be common practice to move around the cabin of other aircraft unrestrained, it is very unusual to do so in a glider. Gliders have a four-point shoulder and lap harness and this is expected to be worn at all times – so much so that checking it is not even a part of the most commonly used glider pre-landing check.

While wearing a parachute on this flight was a bit of an afterthought, I wonder if it was not a factor in Geoff’s decision to undo the harness?

When he realised that he could only reach the screwdriver by undoing the harness, that would have been a good time to sit back and reassess the situation. Was it possible to reach the screwdriver with the shoulder harness undone but the waist harness secured loosely to allow greater freedom of movement? It may have been possible to recover the screwdriver without running any risk of being ejected

A firm hand:

Some gliders (for example, Blanik) are very stable in pitch and can be trimmed to a speed and safely left to their own devices, needing only a gentle guiding hand on the stick, even in quite turbulent air. The Cirrus, however, should have a firm hand on the stick at all times. It is marginal in pitch stability and has an all-moving tailplane which is powerful in effect and very sensitive at high speeds (say, over 80kt).

Pilot induced oscillations (PIOs) were common in Cirrus gliders and you still hear of the odd occurrence even now. It seems to me that going fishing in a Cirrus cockpit, and trusting the glider to remain on an even keel in known turbulent conditions, would have a reasonably predictable outcome.

Some people might say that Geoff should have forgotten the screwdriver and focused on landing safely. But if the controls had jammed, that course of action could have proved disastrous, especially if the controls jammed at low altitude.

So did he in fact do the right thing? No. Perhaps, on learning that he could not reach the screwdriver with the harness on, he should have considered a controlled parachute jump from the aircraft. Would this have been the best solution to this problem? Well, no. After Geoff dropped the screwdriver he said he “began to run through the possible problems the loose screwdriver may cause”.

" While it may be common practice to move around the cabin of other aircraft unrestrained, it is very unusual to undo your harness in a glider. "

With hindsight it’s easy to suggest the perfect solution to every aviation problem. And in this case the perfect solution would have been early identification of the design flaw in this particular aircraft that allows loose objects to interfere with the elevator and aileron control rods.

If the problem had been identified before the flight, a number of remedies could have been considered. A short-term remedy would be to tie one end of a piece of string around any object which could potentially interfere with the controls – pencil, screwdriver, and so on – and the other end to the pilot’s wrist. Even better, a guard could be installed over the bulkhead holes to prevent objects getting through to the exposed elevator and aileron control rods.

What would you have done?

Would you have removed your harness? Would you have left the screwdriver on the floor and chanced a landing? Would you have parachuted out of the aircraft because of the possibility that the controls might jam?

If it had been me, I would have been reluctant to trust the glider to keep me out of trouble while I went fishing for the screwdriver. I would not have been prepared to take my hand off the stick for more than a second or so – nor would I have been prepared to undo my harness.

This means that my fishing expedition would have had limited scope. I’m not saying my decision would have been right, because you can’t argue with Geoff ’s ultimate success, however bizarre the circumstances. Maybe I would have experienced jammed controls if I had followed my instincts and maybe I would have been in deep trouble because of it. The important thing is that Geoff is still with us and that is a great outcome.

Ultimate success: Author Geoff Osborne three months after the accident. These days he flies an Auster J1 and a Grunau Baby II.

"Mein Gott" (VH-GOT) flew at the Gliding Queensland Easter Competition held at Chinchilla in 2009 (piloted by Stephen O'Donnell and his son Luke). Stephen finished second in the Club Class overall results.

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