Yak42 crash, Russia

[Dash8100]

So the captain hit the brakes? (FO: "what are you doing?")

[Machinbird]

So the captain hit the brakes? (FO: "what are you doing?")

Anything is possible. He could have been pulling off power on the center engine or reducing flap setting for example. By then they were in extremis and the aircraft was not rotating.

[HarryMann]

It was rotated, we saw that...

Was it over rotated? Is over-rotation even a possibility with take-off slat on the YAK- 42 ?

Just a thought... early over-rotation > partially stalled wing (l.e.stall) + incidental braking force

[Machinbird]

Was it over rotated? Is over-rotation even a possibility with take-off slat on the YAK- 42 ?

Most likely it was not over rotated, but instead was rotated so late that ground collisions doomed the aircraft. One of the last images I saw before the aircraft hit the camera included what I believe was the starboard main gear strut torque link and it appeared to show that there was still substantial compression of the main gear strut. The wing had not yet begun to bear the weight of the aircraft.

[silverstrata]

Despite increases take-off thrust, acceleration slowed significantly, which may be explained by the appearance of additional braking force.

As I said before, the brakes being on would explain this crash. The only thing burning in the lake, was the wheel bogey, which would be better explained by very hot brakes than a fuel spillage. And that slowing of the aircraft after 210 kph again looks suspiciously like brake application.

Perhaps the brakes came on accidentally. Perhaps the f/o thought they were too far down the runway, and decided to unilaterally abort the t/o by applying the brakes. (Would not have been the captain, as he was calling for full power.).


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[Kulverstukas]

LifeNews claims that this is trail of right main wheels, found by MAK at the last 100 m of runway:



This one is from runway treshold shoot minutes right after takeoff:

[ap08]

decided to unilaterally abort the t/o by applying the brakes.

Without saying anything about it?

[silverstrata]

Who knows.

There is many a passenger in a car who subconsciously presses hard on the footwell when they think the driver is too close to the car in front, without saying anything about it (the imaginary brake).

Conversely, if it was a braking system fault, then what could cause brakes to come on uncommanded? It is not a usual system failure. Does the Yak have autobrakes?

Another possibility might be a brake that was binding from the beginning, but the problem worsened as it got hotter. A brake would need to be on for some time, or on very hard, to get enough energy to burst into flames.


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[Kulverstukas]

I don't remember calls for a toxicology test in the latter.

Confirmed negative.

[vovachan]

22 Sept update

Representatives of the Technical Commission of the Interstate Aviation Committee to investigate the crash of the Yak-42 RA-42 434 conducted an interview with engineer for aircraft and avionics, surviving accident. In his opinion, there were no complaints abt the work of aircraft in the previous flight, in preparation for accident flight and during accident flight. His words clarified the actual distribution of passengers and baggage - in the front cabin was management of the team and coaches, the team was in the second cabin, the bulk of luggage was loaded into the rear trunk.

[Pali]

I've read a report about the possible causes of the crash now. It seems that one of the pilots pushed brake during take off by mistake. The brake pedal seem to have "tricky" design (said test pilot Alexander Akimenkov) and you are supposed to put down your foot from it. If not then involuntary break force may be the result during TO.

Mysterious breaking force impeded rotation. PF fought with the stick and pulled too hard so once airborne the AoA of Yak42 exceeded the critical value of 19 deg (optimum range is 10-12), stalled and crashed.

The sole survivor board engineer Sizov who has been traveling as a dead head said that he knew that plane is about to crash. PAX were very nervous during TO because it took too long and when the plane went into air he recognized that crash is inevitable.

[Karel_x]

...to have "tricky" design...

exactly he said:

...из-за примитивной особенности педали тормоза. По его словам, на педали есть железная кромка. При взлете ноги снимают с педали так, чтобы каблук слегка прижимался к полу. Если каблук полностью остается на педали, то летчик может непроизвольно внешней стороной ступни жать на эту кромку и тем самым производить торможение.... Нужно учиться летать

...because of the simple feature of the brake pedal. According to him, the pedal has steel edges. In time of take off the foots should be removed from the pedals and the heel lightly pressed to the floor. If the heel ramain completely on the pedal, then the pilot may inadvertently press the outward side of the foot to this edge, and brake... We have to learn to fly.

[vorra]

The sole survivor board engineer Sizov who has been traveling as a dead head said that he knew that plane is about to crash. PAX were very nervous during TO because it took too long and when the plane went into air he recognized that crash is inevitable.

The survivor is an avionics engineer, not a board/flight engineer of any kind. The media stubbornly refer to him as a flight engineer.

[vovachan]

Google with some edits:

Chairman of the Technical Commission of the Interstate Aviation Committee reports that the necessary stages of the investigation the crash of the Yak-42D w / n 42 434, which took place 09.07.2011 in the town of Yaroslavl, are satisfied, including:
- Special studies of drums wheels, brakes and braking systems of units, as well as the technical condition of aircraft tires. At the conclusion of the FAA "State Center" Safety in Air Transport ", failures of these units has not been detected;
- Completed processing and analysis of recorders, including analysis of engines, airborne systems and equipment, crew actions, identification of the voices of the members of the crew;
- Mathematical simulation of an emergency flight;
- Flight experiment conducted on the basis of LII. MM Gromov, with the participation of experienced test pilots for the program, coordinated Research Institute of Civil Aviation and LII approved flight-Methodical Council LII. The data obtained in the experiment, confirmed the results of mathematical modeling of an accident flight;

- Analyze all of the documentation submitted by airlines "Yak Service", including the organization of flight operations, crew training, medical records and test results and airlines Rostransnadzor Rosaviatsia after the accident;
- Analysis of accidents and disasters of aircraft Yak-42 for the entire period of their operation with the calculation of probability estimates failsafe systems and components, etc. According to available data in the Technical Commission for the period of operation of aircraft Yak-42 there has been no incident, including accident, for reasons related to ergonomics cockpit.

The technical committee has all the necessary materials, surveys conducted by research institutes and centers, flight and technical experts to establish the systemic and immediate causes of all relevant factors and circumstances of this accident, as well as developing a set of necessary measures for safety.
The work will be completed within the next 2 weeks.

[liider]

MAK conclusions (in Russian):

http://www.mak.ru/russian/investigat...s_ra-42434.pdf
http://www.mak.ru/russian/investigat...l_ra-42434.pdf

Both pilots had a most of experience on Yak-40, where the position of feet on pedals differs from the Yak-42.
The FO had a bigger leader authority than the Capt. The FO blood contained some phenobarbetal, which is prohibited for pilots, and had a neural disorder (polyneuropathy).

Takeoff weight, V1, V2, Vr have never been calculated.

Someone inadvertently pushed the brakes, and the braking power didn't allow to lift off, then the full power was selected, both pilots started pulling the yoke, it didn't help.

At the end of the runway, Capt. pushed the yoke for 1 second, the FO asked "What are you doing?" and then the Capt. pulled it back again. The flight engineer after noticing the movement of the yoke forward, immediately moved the throttles back, but after explicit of the FO: "What the f'*k?!" and the command of the Capt. "Full Power!" moved them back to full power.

After losing the braking power on the grass, the plane lifted off, stalled and crashed as it was described in the earlier comments.

[vovachan]

PS the report also finds both pilots continued to fly Y40s with its different arrangement of pedals in between the Y42s which contributed to the confusion.

[jcjeant]

Hi,

More: (in english)
Crash: Yak Service YK42 at Yaroslavl on Sep 7th 2011, failed to climb on takeoff

[worried SLF]

If I understand the report correctly prosecution might find this "Yak Service" a very "interesting" company. How many years in jail is the management facing now?

[North Shore]

At the end of the runway, Capt. pushed the yoke for 1 second, the FO asked "What are you doing?" and then the Capt. pulled it back again. The flight engineer after noticing the movement of the yoke forward, immediately moved the throttles back, but after explicit of the FO: "What the f'*k?!" and the command of the Capt. "Full Power!" moved them back to full power.

Crew coordination, Russian-style

[vovachan]

Here comes the MAK animation! You may want to ff to around minute 13. Not much happens before

http://www.youtube.com/watch?feature...&v=rdORSIwJgwE