This is info from the accident investigation report, from the French version of the NTSB (I believe), the BEA:

A. Mixed ground test crew of 9 on board: some from Airbus proper, based there in Toulouse, some from the Abu Dhabi-based contractor working on the airline’s behalf.

3 people in the cockpit for the test: 2 from Airbus, one from the contractor.

Running the test, in the right seat of the cockpit, in charge of the all controls: Airbus technician, 15 yr employee, 9 yrs experience testing these engines. When he was alerted that the aircraft was moving, his only actions were to kill the parking brake while simultaneously stomping on the main brakes.

In the left seat, observing the test: contractor employee, alerted the test tech that the aircraft was moving. Has no specified role in the test other than to observe.

((This is wrong. The Airbus maintenance manual says that BOTH operator and observer must be STANDING on the MAIN brake pedals during high power runs. NOT the parking brake. When I do it in the A320, my partner and me literally stand on the brake action…..it lifts my butt up out of the seat. I once read that many pilots fail to use maximum braking in aborted take-offs because they aren’t used to giving it their all. So when I run at high power I literally STAND on the toe action of the rudder pedals. Although my trainer used parking brake only….and a lite fuel load at that. Never saw the aircraft move at high power. Not even close. This investigation still doesn’t answer all questions. Maybe after running and getting fully warmed up before the last high power run, maybe the tip clearances got tighter and the engines were producing a little more thrust than the book says.))

In the “service” seat (like the navigator’s seat, only the A340 ain’t got no navigator, I don’t believe): Airbus-employed test pilot, 9 yrs experience as a professional pilot, 7 as a test pilot, not type rated (i.e., not an A340 pilot), perhaps a manager qualified to supervise such tests. Once again, no specific role other than to observe, but in the end it was him who pulled the throttles back.

((I’m surprised he didn’t pull the “Thrust levers” back sooner, being a pilot. By the way, Airbus doesn’t call them throttles….because there is no physical connection to the engines as we see here in spectacular vivid example. For that reason they call them “thrust leevers”. In this case the thrust levers were severed from the aircraft and the engines continued to do what they were designed to do. Classic Unintended consequences.))

B. There were two main causes: 1) no chocks were used to hold the aircraft’s wheels in place during the test.

((Chocks aren’t needed. What if you were an airline operating that plane and had to taxi to a remote part of the field to do high power runs?…like we did….is someone going to follow you out there to place wheel chocks? The answer is, NO. It’s impractical.))

2) All four engines were brought to full power to test one leaky engine. Procedures required the use of chocks and running up two engines - the one leaking and one on the other wing (to prevent torquing and yawing of the fuselage). These two procedures had been frequently ignored by all Airbus technicians at the test center for some time.

((I’ve heard, that is the Airbus culture….a little arrogant. I’ve heard that they are not too strict on personal protective equipment either, in this day and age where that has become the norm all over the world. HOWEVER, the factual part of the report says that the parking brake is adequate for all four engines. The cockpit technicians probably wanted a little time running all four engiens at TOGA for experience. Nothing unusual or negligent in that at all. What do you think they do when they do a “High power assurance take-off run”? They cook those babies, all four of them, at TOGA for 2 or three minutes and then take a snap-shot of parameters for the record. It’s shaking too badly to write it down…they have to use the snap-shot button to record their readings and write them down when they get the power back to idle. I think there is more to this story than we are hearing…..remember, there are lawsuits and insurance companies being dealt with here. We may never hear the whole truth.))

Short answer: the test was done improperly, not in accordance with written procedures and standards. The fault of the Airbus technician.

((You are correct only in saying it was the fault of the Airbus techincian. His only fault was in not pulling the thrust levers back to idle. It’s that simple. It’s totally inexplicable. It’s also inexplicable that the pilot obsever didn’t say, “idle, idle idle!” And seeing a failure to idle the engines, pull them back himself. What was he waiting for? However there is a somewhat lack of training about the systems knowledge fact, that center-gear braking is inhibited during max steering angle. The taxi mechanic should have known that. He should have known that for max braking, to leave the steering tiller alone.))

Contributing causes: 1) the full power of four engines is almost exactly equal to the braking power of the A340s parking brake and the frictional coefficient of the test area’s tarmac, hence the aircraft only moved when shaking of the aircraft and the burning off of fuel lessened the overall braking coefficient. 2) The technician tried to use the brakes alone to stop the aircraft rather than retarding the throttles as well.

((Number 1 is not a contributing factor at all. As stated in the factual presentation of the report, the braking coefficient of the A340 is WAY more than adequate for the parking brake. More than twice as much as required by regs. Further, number 2 is not a contributing factor either….it’s the ONLY factor. Failing to maintain control of his aircraft by not retarding the thrust levers was the ONLY fault in this incident. Having said that, a design flaw is that during steering, the center gear does NOT contribute to braking…however it DOES contribute to a loss of braking coefficient by taking weight off of the main gear. That’s a design flaw. “NO” you say? It was, in this case. It went beyond academic discussion, these guys proved it.))

C. Fun fact: the numbers 3 and 4 engines could not be shut down after impact because the throttle control connection to them had been severed. No. 4 was finally killed over two-and-a-half hours later when enough water and fire-fighting foam had been pumped into it to snuff it out. The No. 3 engine died at 1:25 am the next morning - 9 hrs later - when it ran out of gas: it was too jammed into the wall to get any water/foam into it. Now THAT’S hi-larious. And not a bad advertisement for Rolls-Royce engines, it seems to me.

((…but a bad advertisement for fly by wire control systems. Those X X engines should be able to be shut DOWN in an emergency. What if it had been a “normal” crash out on the field? What then? How incredibly dangerous to have a commercial airline engine running at maximum thust out of control for 9 hours! That’s strictly unacceptable. The JAA needs to step in and demand a fix for that. Who knows…remote emergency shut-down control panels…I don’t know. Something. Anything is better than letting a high power jet engine run out of control for 9 hours. It could have broken loose from the wreckage and gone airborne….who knows how far it could have gone. Miles I should think.))

((Also I didn’t read anywhere in the report any mention of the taxi crew pulling the aural warning circuit breaker. ….although that is common practice on many types. I often forgot to pull the warning breaker but instantly knew what it was when it went off….and consequently ignored it. That’s mostly what we did, we simply ignored it because we didn’t want any false warnings on the ECAMS and really didn’t want to silence any potential warnings whatsoever. We wanted everything at “SYSTEM NORMAL” status on the ECAM. At less than TOGA power settings we would dial in “flaps and slats 1″ or whatever it took to silence the dang horn.
I find it hard to believe that an experienced taxi mechanic let this happen. I think it is possible that someone in the cockpit DID pull a breaker and accidentally disabled the brakes. By the time the taxi mechanic would realize what had been done to him, it would be too late to recover the aircraft. He was along for the ride….other than pulling back the dang thrust leevers. (which wouldn’t have been enough to stop the aircraft if brakes were disabled)
Someone else mentioned something about he thought you COULD indeed land with the brakes on….but thats not true of modern airliners. They need to sense weight on wheels to allow brake pressure. If the aircraft was tricked into thinking it was in the “air mode” then brakes would indeed be disabled. These electronic aircraft have all kinds of “gottchas”. Sometimes pulling a circuit breaker ACTIVATES a system rather than de-activating it because it’s “normal” state is active or “on”.))

A DHC-6 TWIN OTTER is a prop Jet (Turbine Engine) Aircraft perfect for this
type of operation (High Altitude, Short Runway) Unless the aircraft was im
poor mechanical condition, or overloaded. The most expensive aircraft made
would not necessaraly avoid an accident that was possibly Pilot Error, or an
aircraft malfunction