BA056 JNB-LHR Incident.

[johan_jnb]

L337 - Simply put, you are out over the bush at about 100' doing 195kts, climbing.

Sorry mate but there is a town called Kempton Park which is north of 03L perimeter, starts around 500m from threshold - stretching 7kms north and around 4-5 kms either side of flightpath out. I live in this town and believe me, this incident has made quite an impact on thousands of aviation/JNB-airport employed people living in this town...

[L337]

Dear me. I retract the word "bush" and would like you all to insert "Kempton Park" in it's place.

The point I was trying to make is that you are not over the runway. So if the you touch down again you are not going to "bounce" off a nice friendly runway. But bounce into "Kempton Park".

[Captain Airclues]

The stick shake occurred at 12.5 feet radio

It stopped at 32.8 feet radio.

[TopBunk]

The stick shake occurred at 12.5 feet radio

It stopped at 32.8 feet radio.

But the key question is what was the time betwen the two heights? I speculate that it was looooonger than normal.

Also, I believe that the raising of the gear resulted in the air-ground logic switching to Air mode, which resulted in the LED's driving to the normal positions by 160ft radio.

It just may be that raising the gear was a superb decision that guaranteed the successful outcome, much as raising the flaps to 20 greatly assisted the outcome for BA38.

[Da Dog]

M.Mouse said

Presumably a stall warning indicates the aircraft is approaching the stall. What are the standard stall recovery actions on the BA B747?

My manuals for the B777 categorically state do not alter the aircraft flap or landing gear configuration so does the B747 uses different procedures?

L337 has beat me to it with a fine explanation

Perhaps if you were desperate to know the answer to this question, you could have asked on the BA section of the BALPA forum where there is a long running thread on the JNB incident or indeed the tech part of said forum.

Or perhaps you were afraid that such a question could potentially be observed as a slight to the actions of the crew on the day!

[Joetom]

The DFDR will make interesting reading indeed.

Would guess the L/E waited for gear in air mode via the tilt prox sensors/logic, but guess it could be gear leaver position or position of gear.

Question, when L/E deploy, does lift reduce in the early stage on the 747, I would guess it does ? anyone know ?

[M.Mouse]

Or perhaps you were afraid that such a question could potentially be observed as a slight(sic) to the actions of the crew on the day!

Da Dog

At no point have I criticised the crew and nobody has actually confirmed whether the gear was raised immediately or not and if it wasn't at what point it was raised. It may well be the case that the stick shake caused them to leave the gear where it was and they then raised it when the stick shake stopped. Plainly whatever the crew did worked.

I do not subscribe to the view that they would have had sufficient time to analyse the situation, decide that they MIGHT have to shut down two engines, and that raising the gear while near to a stall was the lesser of two evils.

The BALPA forum consists of a thread almost entirely composed of unqualified congratulations so hardly the place to discuss the merits of various courses of actions but then it made your attack easier.

Full Wings said:

Makes a lot of sense. It probably wouldn't have taken much of a reduction in pitch attitude for the aircraft to make ground contact and I expect that would have been beyond the end of the paved surface...

So raise the gear, temporary increase in drag, lower the nose to maintain airspeed, er..........

I'm off. I will just have to learn to blindly praise every perfect crew before the facts are known rather than try and learn from the incident whether anything done was less than optimum, albeit successful, just in case I am faced with the unthinkable which, as has been pointed out, is outside the scope of any known procedure.

[Da Dog]

M.Mouse,

The point I was trying to make was that, If you had asked the question I referred to on the BALPA forum I am 100% confident that you would have got a swift and concise answer, instead you elect to labour the point on an open, anonymous forum.

I can't think why.

I'm off

have I touched a nerve?

[GS-Alpha]

I have as little idea about what actually happened as the next guy. I am simply glad this incident did not turn into a nasty accident.

Also, I believe that the raising of the gear resulted in the air-ground logic switching to Air mode, which resulted in the LED's driving to the normal positions by 160ft radio.

Surely you would be unable to raise the gear (without using the over-ride) if the air-ground logic was still in ground mode.

Were the REV indications only present once airborne, or did they show during the takeoff roll? It could be that the inboard and midspan LE flap groups retracted during the takeoff roll, but then re-deployed once the gear tilted as it got airborne? Pneumatic movement of the flaps is relatively quick, but would still not be in position for a short period of the initial airborne time (during which the stick shaker would likely activate).

[M.Mouse]

The point I was trying to make was that, If you had asked the question I referred to on the BALPA forum I am 100% confident that you would have got a swift and concise answer,

A swift and concise answer on the BALPA forum? I am still laughing at that one.

have I touched a nerve?

Nope. Just when attacks get personal it is time to go.

[Da Dog]

I am sad for you M.Mouse that you hold your work colleagues in such low esteem, I know of many high caliber trainers who would have been happy to answer your question either in public or with a private message.

However I suspect you already knew the answer

[Swedish Steve]

Were the REV indications only present once airborne, or did they show during the takeoff roll? It could be that the inboard and midspan LE flap groups retracted during the takeoff roll, but then re-deployed once the gear tilted as it got airborne?

The auto retract of the l/edge flaps is only armed on the ground. Therefore when the aircraft became airbourne this signal from the Thrust Reverse relays would have been lost and the l/edge flaps would have deployed again.

[gas path]

About 10 secs for L/Edge flaps to transit, and (from memory) about 16 secs for the gear to (physically) transit. (a little bit longer for the EICAS indication).
GS-Alpha see post 17

[Carnage Matey!]

M. Mouse - have you flown a jumbo or other heavy four engined aircraft? Perhaps you are used to flying a twin around where the potential loss of 50% of your thrust is no great problem. You don't need me to tell you that it's different in a jumbo. You are implying the crew responded in Pavlovian fashion, raising the gear simply because that's what they always did with no thought I'd analysis. I suspect any competent 744 crew on seeing 2&3 rev amber after V1 can make a pretty good snapshot call as to what the biggest threat to the aircraft was. If you had two unreliable engines on your 777 after take off would you faff around with a T-DODAR trying to work if raising the gear would help I'd hinder?

[TopBunk]

Aircraft due to leave JNB later this evening to ferry back to LHR. Both nos 2&3 reversers are/will be locked out!

[Sir George Cayley]

Let a just culture prevail

Let's not rush to judgement or excessive praise, and take the 'no blame' route.

That said, if anyone can let me know the tail number of a/c in question I think I'll let it do a few sectors without me!

Sir George Cayley

[4PW's]

I read PPRuNe in the hope of learning what I didn't know I did not know. And whenever I am lucky enough to find the limits of my knowledge before they bite me, I return to my company issued Boeing 744 CD-rom, a poor cousin to the erstwhile manuals.

I also read PPRuNe in the hope of re-learning what the passage of time has caused me to unwittingly and unwillingly forget. There's been a lot of forgetting going on in my overfull, greying head lately.

A few critical points have been taken from this very important thread:

One is the undeniable fact of it being populated by some very testy and apparently uneducated people on the matter of aviation who seem uncommonly keen to discredit tried and true procedures, to question proper process, or to nit pick well worded posts written by highly experienced pilots commiting the inexcusable crime of not naming an obscure and forgettable grouping of dim lights he has overflown on countless departures over the wider bush that is Africa.

Another is that the BA036 crew did an outstanding job.

Most importantly, my thirst for knowledge has been reinvigorated by a sense of self preservation. Fate is the hunter, and though I know the B744 airplane well, I don't know it as well as I'd like. Given it is my chariot in the workplace, I am forced to review my training in the case of being faced with the unthinkable.

I don't know how this incident would have transpired were I on the flight deck any more than I know how this afternoon's flight will ultimately work out until the brakes are set to park on the second and final stand.

Anything could happen, according to Boeing.

Which is sufficient reason to review my CD-rom, hateful disc of plastic that it is; to rely not on prayer but experience, training and a cool head, and to hope that my clear thinking cap with its well receded hairline is firmly latched if and when events become as unpredictable as they did for the BA crew departing Jo'berg.

[BarbiesBoyfriend]

PW

Well said.

There, but for the grace of God, go us all.

[Globaliser]

Originally Posted by Sir George Cayley

That said, if anyone can let me know the tail number of a/c in question ...

G-BYGA? According to Heathrow & Gatwick Airport Movements it went out on 10 May but didn't arrive back on 12 May.

[Willit Run]

I would be willing to bet that the gear retraction was in progress when the stick shaker was activated. ONce you notice an increase in altitude from the baro and radio, up comes the gear!

I have seen some mind blowing wierd things happen when moisture condenses on the logic cards. Cool avionics, then a blast of hot humid air , condensation happens.