Aircraft Crash in Moscow

[Kulverstukas]

From Aviaforum

KYA
How was RCL on previous flights moved? Or was it because 1/3 of rwy was already back?

Toba
Five previous flights (all available FDR recordings for this CPT) was the same "in one move".

[lomapaseo]

Just checking (I probably missed somewhere0

Was the missing WOW swiitch on the one gear due to a faulty switch or indeed there was no weight on wheels due to high speed ?

If this switch does not activate does it mean no spoliers or reverse on all engines?

After the capt commanded the engines off why did the reversers deploy or was it after the deployment?

I'm led to believe that WOW switches sometimes fail and most pilots accomodate this failure mode by not commanding full reverse and relying on brakes. Is the causal chain in this case that simple or was there a significant pucker factor added into the scenario by too high a touchdown speed as well leaving little time to sort things out?

[BOAC]

If this switch does not activate does it mean no spoliers or reverse on all engines?

- worse! As I read the post, it means NO WHEELBRAKES on the 'failed' leg - that cannot be right, surely?

[Karel_x]

All WoW switches were OK, there was crosswind and the a/c had a left bank. If not both WoW signal activated, no automatic spoiler deployment. Crew didn't deploy them manually (!). Without spoilers, not automatic brakes and not unlock of thrust reversal... If I understood, the only fault of a/c was lack of mechanical lock at the thrust levers, that allowed PIC to move lever "in one movement" (without waiting for green lights) to reversal position.

For me, it is little surprised, that MAK spoke only about mechanical fault and not about human factor (speed landing, lack of spoilers manually, incorrect work with thrust levers, not TOGA etc.)

[Kulverstukas]

I see key issue in "one move" reverse deployment to MAX REV which was, as said at aviaforum, common practice of this CPT (and as roumors are at RW in general). Added to mess their habit of using autobraking and autospoilers.

IF it coupled with "normal" landing, WoW swithes will allow reverser deployment and everything is OK. This time overspeed + side wind + empty a/c + wrong practice =

[BOAC]

OK guys - what do you make if this?

The pressure in the wheel brakes left (compressed) landing gear was up to 50 kgf / cm ², the pressure in the wheel brakes right (not compressed) landing gear was missing.

- either autobrakes work or they do not. Is this because the anti-skid was releasing the pressure due to no weight on the wheel??

[Lyman]

BOAC

Isn't autobrake sensitive to spin? If the wheel is not turning, the brake thinks it is locked, and "releases".

But I read the original to suggest that WOW was necessary for brake activation...perhaps not.

WoW is to do with 'activation', spin to do with 'operation'...no?

[BOAC]

.....err - isn't that what I said?

[Lyman]

Not weight on the wheel, no spin....? The wheel will not turn w/o weight, and the brakes will not compress if the wheel is not spinning.

They are related, but different?

[broadreach]

Sounds more and more like Congonhas albeit for different reasons.

[vovachan]

Can we assume that maybe after the previous rather hard landing in Czech caught on video (for which the f/o caught flack) the captain was showing him a "teachable moment" and made it go a bit too smoothly by half so the wheels never hit the ground hard enough to trigger the automatics

[PJ2]

broadreach;

Re, "Sounds more and more like Congonhas albeit for different reasons. "

Actually it sounds more like Warsaw.

[lomapaseo]

Agree

[CONF iture]

Originally Posted by Sunamer

Aircraft exited the runway after 32 seconds from landing, with AC being on the center line, the IAS was at about 215 km/h during the process of rolling out.

Sad to think that simply pulling on the flight controls in that late stage would have been the perfect escape.

[PJ2]

Sad to think that simply pulling on the flight controls in that late stage would have been the perfect escape.

Yes, in hindsight that could likely have been successful. But of course during their 30+ seconds on the runway the uncertainty resulting from the inevitable cognitive dissonance from two opposing awarenesses . . ., that they were "in reverse" (because it was selected), and that they were "accelerating" made such a decision extremely difficult in the time available. Would they take an airplane into the air immediately after cancelling reverse? It's occurred before with disastrous results, as discussed in the thread.

The confusion may have been settled by looking at the reverse lights and a quick decision to take off again may have been possible.

Is this not an entirely preventable accident?

This was not a complex system; - it was a simple thrust-reverse system which permitted an ordinary and experienced crew the selection of high thrust levels with the reverse levers in "Reverse" but without the reversers deployed. I would have thought that such old and basic systems as reverse thrust installations would have been designed, (including sufficiently protecting single-point failures such as the sensors from environmental effects or damage), to prevent such circumstances.

[CONF iture]

Originally Posted by PJ2

Would they take an airplane into the air immediately after cancelling reverse? It's occurred before with disastrous results, as discussed in the thread.

120kt with no more rwy to spare ahead is already a sure disaster in the making, unless it is all flat and obstacle free.
Pull and toga as a late and desperate rotation can be a sensible way to react too ... It's also occurred before with positive results.

On the technical side, I fully agree with your last paragraph.

[PJ2]

Originally Posted by CONF iture

120kt with no more rwy to spare ahead is already a sure disaster in the making, unless it is all flat and obstacle free.

Yes, agreed, no options for stopping. The certainty of 190k does place an inevitability about it.

In considering a go-around in such rare circumstances I would think that everything one has ever learned from training would resist the thought and the temptation to takeoff after reverse had been deployed.

There is also the inevitability of not knowing the position of the reversers and not having time to check the lights and decide one's fate; - one doesn't know whether they'd deploy in the air. It's only slightly less a certainty, and a terrible choice no matter what.

What is disconcerting about this now that we know a bit more is the absence of a fix since it was a known issue with serious flight safety implications.

Because I'd experienced it in winter on an A320 once, I do recall the issue where if one's landing was too smooth and on a wet or contaminated runway, one couldn't get reverse or braking until either WoW or wheel-spin was sensed and the spoilers deployed. IIRC correctly, (more in doubt as I get further in time from the cockpit!), Airbus addressed the Warsaw issue by designing a two-stage oleo to get the WoW signal more reliably and permitted either main gear wheel-spin signals to satisfy the "okay to deploy spoilers" condition. This last occurs when reverse is selected on at least one engine and only one of the main gear wheel spin signals is received the spoilers will deploy to 10deg to reduce lift and get the second main gear compressed for full spoiler extension.

The reports will be very interesting as will the fix to the reverser issue.

[Clandestino]

Whether it turns out to be design fault, maintenance problem, combination of the two or something completely different, once again it is demonstrated why it is good idea to check for reversers green before feeding them anything above idle.

Originally Posted by CONFiture

Sad to think that simply pulling on the flight controls in that late stage would have been the perfect escape.

So, the pilots realize that despite their pulling reverser levers fully back, engines are producing full forward thrust. They promptly and correctly diagnose the problem which they have never seen before and decide to take it airborne while holding the reverse levers where they are. They climb away to safe altitude and airspeed which would allow transition from full reverse selection forward to climb power , all the time being lucky reversers don't deploy while airborne.

Problem with this scenario is it is too much to expect even of Dan Dare or Pirx the pilot.

Originally Posted by PJ2

This was not a complex system

Yup. Given reactions on PPRuNe, they alternatively suck when they are simple then suck when they are complex, depending on nothing else but what was the contributing factor of the last accident in the collective memory.

[Heathrow Harry]

I think , over the years, running off the end of the runway, has proven to be kill fewer people than trying to go round after a seriously botched landing as this obviously was

[Kulverstukas]

Mamaladse:

CPT at approach when 2P commented "Speed 280 kph too high" replied "You better did not piss me off"