Loss of all Generators
Joined: Jun 2001
Posts: 4,777
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From: Blighty
Er, by using the alternate brakes (without antiskid) and using differential braking for directional control.
Can we have a harder one please.
(PS - this question is a bit type specific. Did you have a type in mind? The situation which you describe wouldn't happen in the three civilian types I have flown.)
Can we have a harder one please.
(PS - this question is a bit type specific. Did you have a type in mind? The situation which you describe wouldn't happen in the three civilian types I have flown.)
Joined: Dec 1999
Posts: 0
Likes: 1
From: UK
Er sorry Dan I'll spell it out.
Years ago a mate had this in the sim and of course when all the screens go blank nearly everyone shouts Stop!
Only problem is that a whole bunch of nice stopping stuff probably isn't working.
Years ago a mate had this in the sim and of course when all the screens go blank nearly everyone shouts Stop!
Only problem is that a whole bunch of nice stopping stuff probably isn't working.
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Joined: Jan 2005
Posts: 4,011
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From: Hampshire, UK
Reversers are not usually included in take-off performance, so no problem there- they are usually just a plus. Alternate brakes should be just as effective as normal brakes. No anti-skid requires carefully brake application- probably multiple applications and affects the efficiency of the brakes. Steering- absolutely no problem- rudder control and diff brakes slowing down. Might have smokey wheels, but not much increase in stopping distance.
Come on- we want a harder one!
Come on- we want a harder one!
Joined: May 1999
Posts: 241
Likes: 47
From: Runcorn,Cheshire,England
Well there's not much point in taking off, as that same stuff isn't going to slow you down when you land either!
Joined: Dec 2000
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From: on the golf course (Covid permitting)
Multiple failures before V1 = stop without question, imho.
I'd personally rather go off the end at low speed (unless it's over a large cliff, for example), than get airborne well above max landing weight with limited electrical life and instrument capacity from the battery(ies) and have to reland in that condition.
No brainer for me ..... as said before, ask a difficult one.
I'd personally rather go off the end at low speed (unless it's over a large cliff, for example), than get airborne well above max landing weight with limited electrical life and instrument capacity from the battery(ies) and have to reland in that condition.
No brainer for me ..... as said before, ask a difficult one.
Joined: May 1999
Posts: 241
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From: Runcorn,Cheshire,England
Granted, take each case on ti's merits and if one encountered such a scenario then important decisions have to be made quickly, But (as a TRE), if you elected to continue in a sim check with me with this scenario i'm afraid, in all probability, you'd be retested!
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Joined: Jan 2005
Posts: 4,011
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From: Hampshire, UK
I am with the stops, undoubtedly. You are below V1 remember. There is only one thing to do with multiple failures like that, and dragging it into the air not knowing exactly what you have and haven't got? Not for me.
Thread Starter
Joined: Jan 2001
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3Greens,If you think Boeing recommends the Stop at or near V1 with this particular failure , then I would suggest writing to them before you start retesting pilots for there decisions after this failure. Why don't you try both decisions in the Sim as you have the chance and come back with your findings.
Thread Starter
Joined: Jan 2001
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Well there's not much point in taking off, as that same stuff isn't going to slow you down when you land either
Joined: Dec 1999
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From: UK
A TRE, wow I'm unimpressed!
For starters TRE's shouldn't make assumptions about it being a Boeing though, should they?
I know it will fly but I'm really not sure about it being able to stop.
BTW I'm not saying I would always go and yes it's an extremely unlikely event. (Like a mid air in the middle of Brazil with the TCAS U/s maybe)
This thread reminds me of an old Avsig thread where all the experts were busy buttering each other up with how easy it is in the sim to control an uncommanded reverser deployment on takeoff. Right up until a very experienced test pilot from Boeing came on and said basically '...if it happens for real your pretty much screwed !'
For starters TRE's shouldn't make assumptions about it being a Boeing though, should they?
I know it will fly but I'm really not sure about it being able to stop.
BTW I'm not saying I would always go and yes it's an extremely unlikely event. (Like a mid air in the middle of Brazil with the TCAS U/s maybe)
This thread reminds me of an old Avsig thread where all the experts were busy buttering each other up with how easy it is in the sim to control an uncommanded reverser deployment on takeoff. Right up until a very experienced test pilot from Boeing came on and said basically '...if it happens for real your pretty much screwed !'
Joined: Aug 2000
Posts: 1,695
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From: Egcc
Our SOPs are to only stop between 80kts and V1 for engine fire, engine failure, winsheer warning or a condition which meant the aircraft was not flyable, like jammed controls. And that is on a Boeing. Johnman makes a very valid point that a circuit and (possibly) overweight landing gives you the full runway length to stop on and not just what you have remaining if you reject at high speed. What would be wrong with getting airborne and starting the APU? From the phrasing of the question 'all' generators would imply those that were running at the time of take-off, which in our operation wouldn't include the APU?
PP
PP
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From: BRUSSELS
Joined: Jun 2001
Posts: 4,777
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From: Blighty
Sorry Stan, I will explain a bit for you.
For a start, in my experience this is a very unlikely scenario. The type your friend was flying may have this as a possibility, but a modern transport aircraft would not get certified if there was a fault which could lead to the simultaneous failure of all power generation on the take off roll. Maybe this was a 'what if' scenaio.
On my current type, I would consider it so unlikely as to be inconsiderable (if you follow my drift). But if it were to happen, there would be a gap of up to about seven seconds before the hydraullic powered emergency generator kicks in and then you will be in the emergency electrical configuration in which you can continue flying so long as you have fuel - albeit with with much reduced services. Flight on batteries would only happen until you lowered the gear and then on only some of the older airfarmes. Now if this were to happen on the take off roll, I would consider that a proabale cause for stopping. It's a major failure. I would have braking from the emergency accumulator to a maximum of 1000psi, which is fine for stopping in most circumstances. Rudder and assymetric braking would keep me straight. But if it was a VMC day on a very short runway I would consider getting airborne and relying on the emergency generator. (You did specify a double generator failure rather than an even more unlikely scenario of complete electrical failure).
All my other types have been 4 engine aircraft with paralleled genarators split into 2 systems. A failure of all generators is even more unlikely. A tie bus fault could lead to the loss of two generators if the protection doesn't work and un-parrallel them before serious damage occurs. But loosing four? Very unlikely.
For a start, in my experience this is a very unlikely scenario. The type your friend was flying may have this as a possibility, but a modern transport aircraft would not get certified if there was a fault which could lead to the simultaneous failure of all power generation on the take off roll. Maybe this was a 'what if' scenaio.
On my current type, I would consider it so unlikely as to be inconsiderable (if you follow my drift). But if it were to happen, there would be a gap of up to about seven seconds before the hydraullic powered emergency generator kicks in and then you will be in the emergency electrical configuration in which you can continue flying so long as you have fuel - albeit with with much reduced services. Flight on batteries would only happen until you lowered the gear and then on only some of the older airfarmes. Now if this were to happen on the take off roll, I would consider that a proabale cause for stopping. It's a major failure. I would have braking from the emergency accumulator to a maximum of 1000psi, which is fine for stopping in most circumstances. Rudder and assymetric braking would keep me straight. But if it was a VMC day on a very short runway I would consider getting airborne and relying on the emergency generator. (You did specify a double generator failure rather than an even more unlikely scenario of complete electrical failure).
All my other types have been 4 engine aircraft with paralleled genarators split into 2 systems. A failure of all generators is even more unlikely. A tie bus fault could lead to the loss of two generators if the protection doesn't work and un-parrallel them before serious damage occurs. But loosing four? Very unlikely.
