Another great sim scenario!
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MMEMatty deserves a reply
IMHO, the STOP call would be based on different situational call in regard to the actual take off brief.
The time frame between the problem and V1, as well as the actual ground conditions, are also relevent. There are good arguments to continue a take off when the book suggests ( demands) an abort....the classic case being a tyre burst, or a two tyre burst at V1-5. (say)...on a length critical take off. The question that is not covered by the good book is....would you rather try and abourt with an unpublished STOP distance, with a MAX weight aircraft, and thus at very high weihg...or heaven forbid..ignore the book. thake the problem into the air...take several deep breaths, consider the problem rationally, and burn off the fuel, find a loooooong runway, with a fire department who has finished the current issue of Beano (sorry Luton), then land at a vastly reduced speed and weight in the first not last third of the runway...and have all the gods on your side.....
Not certain which call I would make....lol
I leave the specific question to typed and current pilots to discuss for you...
windy
The time frame between the problem and V1, as well as the actual ground conditions, are also relevent. There are good arguments to continue a take off when the book suggests ( demands) an abort....the classic case being a tyre burst, or a two tyre burst at V1-5. (say)...on a length critical take off. The question that is not covered by the good book is....would you rather try and abourt with an unpublished STOP distance, with a MAX weight aircraft, and thus at very high weihg...or heaven forbid..ignore the book. thake the problem into the air...take several deep breaths, consider the problem rationally, and burn off the fuel, find a loooooong runway, with a fire department who has finished the current issue of Beano (sorry Luton), then land at a vastly reduced speed and weight in the first not last third of the runway...and have all the gods on your side.....
Not certain which call I would make....lol
I leave the specific question to typed and current pilots to discuss for you...
windy
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How do you think a burst tyre will result in a severe of both A and B reservoir lines on a 737? Would it be physically possible?
I guess not,no way for some piece from the burst tyre to enter the main wheel and severe the lines.
Even if this would be possible you'll have the stby sys for take-off.After that,even with stby disabled,an engine out would be survivable at higher speeds. For landing,I'll do as you said,come to a good position,then reduce the working engine,and glide for landing. (done in the sim,210 kts,flaps up,both eng off,did ok).
To reject at high speeds,with tyre(s) burst would be 100% overrun (did that in the sim also)
The oil from stby will return to tank B...hmm...not true
" A leak in system B does not affect the operation of the stby hyd sys" 13.20.3
Furthermore,the stby sys works with the stby rudder pcu,not the same one used by A or B sys.When in use ( flt control switch to stby rud) the related hyd sys shutoff valve will close,isolating the system.
So ,I suggest, you tell that TRE to review the hydraulics chapter as there've been some changes done.
windy: for tyre burst the 'book' recommends to stop if only bellow 80 kts .Above 80 you should stop for eng fire,failure,aircraft unable or unsafe to fly,predictive windshear.
The definition for unsafe it's a bit tricky.Actually,it gives you the option to reject a take-off due to any reason that you can qualify as an unsafe situation on your oppinion.
I guess not,no way for some piece from the burst tyre to enter the main wheel and severe the lines.
Even if this would be possible you'll have the stby sys for take-off.After that,even with stby disabled,an engine out would be survivable at higher speeds. For landing,I'll do as you said,come to a good position,then reduce the working engine,and glide for landing. (done in the sim,210 kts,flaps up,both eng off,did ok).
To reject at high speeds,with tyre(s) burst would be 100% overrun (did that in the sim also)
The oil from stby will return to tank B...hmm...not true
" A leak in system B does not affect the operation of the stby hyd sys" 13.20.3
Furthermore,the stby sys works with the stby rudder pcu,not the same one used by A or B sys.When in use ( flt control switch to stby rud) the related hyd sys shutoff valve will close,isolating the system.
So ,I suggest, you tell that TRE to review the hydraulics chapter as there've been some changes done.
windy: for tyre burst the 'book' recommends to stop if only bellow 80 kts .Above 80 you should stop for eng fire,failure,aircraft unable or unsafe to fly,predictive windshear.
The definition for unsafe it's a bit tricky.Actually,it gives you the option to reject a take-off due to any reason that you can qualify as an unsafe situation on your oppinion.
Last edited by alexban; 3rd Sep 2005 at 16:54.
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Hi alexban, as you say the bursting of tires is very unlikely to severe the hyd lines, I think.
Maybe it's possible, but...
That was his idea for the illumination of all 4 hyd pumps low pressure.
That's not realistic, as I've said since the beginning.
And, as you say quite correctly, the loss of system A and B fluid will not cause the loss of the STBY system.
Probably his idea was that the tyre burst severes also the STBY lines...
I can imagine him saying: "If ALL pumps are illuminated that means a major structural failure! Don't you think the Standby will also be affected??!"
I still think his scenario doesn't make sense.
BTW, if any of you has got other ideas on what could cause the sudden loss of ALL four pumps during takeoff, please tell me
Maybe it's possible, but...
That was his idea for the illumination of all 4 hyd pumps low pressure.
That's not realistic, as I've said since the beginning.
And, as you say quite correctly, the loss of system A and B fluid will not cause the loss of the STBY system.
Probably his idea was that the tyre burst severes also the STBY lines...
I can imagine him saying: "If ALL pumps are illuminated that means a major structural failure! Don't you think the Standby will also be affected??!"
I still think his scenario doesn't make sense.
BTW, if any of you has got other ideas on what could cause the sudden loss of ALL four pumps during takeoff, please tell me
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Inflight,with a very low OAT ,you can see all pumps illuminated,it happend this year to a few NG ,flying high and with a very low temp.They had to descent to lower FL.It was not a 'major structural failure' as you see ,but can give a ideea of one reason why you can see all hyd lights on.
One other reason I can think off will be a major blast in the wheel well area,but in this case you will feel it for certain in the cockpit
For sure you won't have time ro remark the hyd lights.... 
The TRE may have read about the DC-10 accident,but there is no resemblance with a 737 (no tail engine to severe all lines,a different pcu for the stby....)
Contaminated hyd liquid may cause the lights to come on,but you'll check during walk-around for this condition.And I doubt would happen to both sys at once.
You can tell him that 'if all pumps lights on-major structural failure ' (big blast maybe) it won't be a problem of continuing or not of the take-off.It would be a problem of emergency evacuation.
One other reason I can think off will be a major blast in the wheel well area,but in this case you will feel it for certain in the cockpit
For sure you won't have time ro remark the hyd lights.... The TRE may have read about the DC-10 accident,but there is no resemblance with a 737 (no tail engine to severe all lines,a different pcu for the stby....)
Contaminated hyd liquid may cause the lights to come on,but you'll check during walk-around for this condition.And I doubt would happen to both sys at once.
You can tell him that 'if all pumps lights on-major structural failure ' (big blast maybe) it won't be a problem of continuing or not of the take-off.It would be a problem of emergency evacuation.
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Inflight,with a very low OAT ,you can see all pumps illuminated,it happend this year to a few NG ,flying high and with a very low temp.
You never stop learning
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LEM....
You seem to somewhat misleading us... deliberately?
but only a page later
These are very different scenarios... An isolated inexplicable set of warning lights is not the same as a loud bang, probably swing, AND numerous warning lights.
The first tends one to think of being "go minded"... the second is more Stop territory....
You seem to somewhat misleading us... deliberately?
During the takeoff roll, all four hyd pumps illuminate low press at about 100 kts! (B733)
A tyre burst could severe BOTH A and B reservoirs lines, thus leaving the airplane with all four hyd pumps low pressure illuminated
The first tends one to think of being "go minded"... the second is more Stop territory....
The instructor who thought of this scenario should seriously reconsider the probabilities and hence the training value. A simple reference to the certification requirements or cross check with the manufacturer will help put things into perspective.
This issue is symptomatic of many of the industry’s training problems – the human fascination with the extreme – where we tend to over focus on the rare situations; humans like to fantasize ‘what if I was there’ and ‘how would I have coped’.
For example, there have only been two notable loss of flight control accidents in 10 years, but lets assume 1 rare situation of this severity per year. However, there are at least 5 major commercial CFITs and over 20 overruns per year just for starters; these and other accidents are the key issues to focus on. Many of these ‘routine’ events are actually failures to correctly identifying the situation; the training must address the threat - a possible imbalance of 25:1 with an incorrect focus. The real threat situations are dominated by human error; many instructors contribute to this with an inappropriate focus on rare events.
Attempting to fly with no hyds most probably will result in a crash, stopping without brakes, a similar result, what’s the training value? This is a confidence destroying and negative perspective of incorrect situation assessment / decision making in an unrealistic scenario.
There would be more training value by generating a loud bang before / after V1 without any warnings. To make the bang unusual and surprising try dropping the Jep bag on the sim floor! Then induce severe vibration; is it engine or tyre? But the important question / decision is stop or go!!!
This issue is symptomatic of many of the industry’s training problems – the human fascination with the extreme – where we tend to over focus on the rare situations; humans like to fantasize ‘what if I was there’ and ‘how would I have coped’.
For example, there have only been two notable loss of flight control accidents in 10 years, but lets assume 1 rare situation of this severity per year. However, there are at least 5 major commercial CFITs and over 20 overruns per year just for starters; these and other accidents are the key issues to focus on. Many of these ‘routine’ events are actually failures to correctly identifying the situation; the training must address the threat - a possible imbalance of 25:1 with an incorrect focus. The real threat situations are dominated by human error; many instructors contribute to this with an inappropriate focus on rare events.
Attempting to fly with no hyds most probably will result in a crash, stopping without brakes, a similar result, what’s the training value? This is a confidence destroying and negative perspective of incorrect situation assessment / decision making in an unrealistic scenario.
There would be more training value by generating a loud bang before / after V1 without any warnings. To make the bang unusual and surprising try dropping the Jep bag on the sim floor! Then induce severe vibration; is it engine or tyre? But the important question / decision is stop or go!!!
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Hi NigelOnDraft, if you read with more attention you'll see that the whole story happened to one of our colleagues, not to me.
So I reported what the tam-tam made available to some of us.
What happened is all four pumps illuminated before V1.
I'm not sure there was an audible bang or not.
Misleading deliberately?
alf5071h,
excellent post, outstanding!
These are exactly my thoughts, as especially here some instructors like to set up very complicated and tricky scenarios, with multiple failures and so on....
when we have people having a hard time flying a manual circling or go around!
So I reported what the tam-tam made available to some of us.
What happened is all four pumps illuminated before V1.
I'm not sure there was an audible bang or not.
Misleading deliberately?
alf5071h,
excellent post, outstanding!
These are exactly my thoughts, as especially here some instructors like to set up very complicated and tricky scenarios, with multiple failures and so on....
when we have people having a hard time flying a manual circling or go around!
ECON cruise, LR cruise...
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Re. sim scenarios...
The scenario your colleague was given, LEM, could have training value - as a discussion point. I think that all the excellent replies above show that the isolated illumination of all 4 pump low press lights is not in itself a cause to abort, but further circumstances might make the stop call the only right call to make.
The problem often occurs when the TRI/E in question brings along an "eye-opener" scenario - but with a pre-concieved "correct" crew reaction & outcome. The eye-opening scenarios are great, but the crew have to sort it out for themselves. Only if they embark on an obviously dangerous course of action can you start giving out and using phrases like "Next time around, a different approach might be warrented, gents...". That - BTW - is one of the good things about instructing. You are suddenly treated to new approaches that you had not thought of yourself - approaches that might very well work, that is.
So - good scenario, but put to dubious use
Brgds fm
Empty
The scenario your colleague was given, LEM, could have training value - as a discussion point. I think that all the excellent replies above show that the isolated illumination of all 4 pump low press lights is not in itself a cause to abort, but further circumstances might make the stop call the only right call to make.
The problem often occurs when the TRI/E in question brings along an "eye-opener" scenario - but with a pre-concieved "correct" crew reaction & outcome. The eye-opening scenarios are great, but the crew have to sort it out for themselves. Only if they embark on an obviously dangerous course of action can you start giving out and using phrases like "Next time around, a different approach might be warrented, gents...". That - BTW - is one of the good things about instructing. You are suddenly treated to new approaches that you had not thought of yourself - approaches that might very well work, that is.
So - good scenario, but put to dubious use
Brgds fm
Empty
Alexban,
Re:
This was a known problem on NG’s due to water trapped in the reservoir pressurisation system which froze when cold soaked and blocked the reservoir bleed air supply causing cavitation at the pumps. There is a mod available (SB 737-29-1106) which fixes this and another problem. You can tell if your aircraft has been modified because there is only one reservoir pressure gauge in the wheel well.
Re a double (or triple if you count the standby system) hydraulic failure on take-off: It has not happened in 38 years of 737 operations and I can’t see it happening, but nothing is impossible in aviation.
S&L
Re:
“Inflight, with a very low OAT, you can see all pumps illuminated, it happened this year to a few NG.”
Re a double (or triple if you count the standby system) hydraulic failure on take-off: It has not happened in 38 years of 737 operations and I can’t see it happening, but nothing is impossible in aviation.
S&L
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These impossibly idiotic scenarios described above have been a feature of simulator "training" for decades. Management pilots who dream up this nonsense get bored with routine simulator sequences and we all know that the Devil makes work for idle hands. We had similar nonsense at Central Flying School where as part of an instrument rating test in a Dakota, one had to perform a single pilot, asymmetric, limited panel (no AH or DG) NDB aurul null instrument let down.
The recent dreadful accident in Indonesia where a 737-200 of Mandala Airlines appears to have done an airborne abort seconds after lift-off (gleaned from notoriously unreliable media reports), is one accident where simulation of the events could be demonstrated in a simulator to show the potential for disaster caused by a late decision to abandon a take off. It looks like the Mandala 737 may have suffered an event very late in the take off run that for some reason caused the captain to abandon the take off- - with disastrous results.
Rather than invent complicated and highly unlikely non-normal scenarios such as those described in this thread, there would be better value if crews were given an event at V1 or VR or even V2 that has previously happened in real life and which has caused a reflex abort action which proved quite dangerous
For example, a door warning light coming on, or a generator failure light, or a reverser actuation - things like that which require fast and correct action.
The recent dreadful accident in Indonesia where a 737-200 of Mandala Airlines appears to have done an airborne abort seconds after lift-off (gleaned from notoriously unreliable media reports), is one accident where simulation of the events could be demonstrated in a simulator to show the potential for disaster caused by a late decision to abandon a take off. It looks like the Mandala 737 may have suffered an event very late in the take off run that for some reason caused the captain to abandon the take off- - with disastrous results.
Rather than invent complicated and highly unlikely non-normal scenarios such as those described in this thread, there would be better value if crews were given an event at V1 or VR or even V2 that has previously happened in real life and which has caused a reflex abort action which proved quite dangerous
For example, a door warning light coming on, or a generator failure light, or a reverser actuation - things like that which require fast and correct action.
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Lem I totally agree with you but the analysis that the TRE made is obviously right from a theoretical point of view but not so easy to apply in an actual situation I would say. At that speed you are so close to V1 that this kind of analysis is really unlikely. One thing is if you hear a big "bum" of bursted tyres and then you get the 4 hyd pumps low press. Probably you are not really understanding what's going on but you feel something will be unsafe to fly very soon and you stop. Bursted tyres + accumulator press only will maybe lead you to an overrun... on the other side if you go, you fly manual reversion (not a big deal) al low speed and maybe you will also loose the stby hyd... and if an engine fails you die... ok but come on ... both the cases (ovverrun and go decision) are extreme...
I would have done exactly what you did in the sim, especially if I had wet runway or LVTO.
I would have done exactly what you did in the sim, especially if I had wet runway or LVTO.
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I completely agree with BOAC in his earlier post – “but it has got people talking.”
Unfortunately, there are a lot of “unanswerable” questions in this business. Do you “go” when you really shouldn’t? Do you “stop” when you really shouldn’t? What IS the right answer? There probably isn’t a single right answer. I’ve always thought it better for me to consider what I would do under similar circumstances and, hopefully, talk about it with some of my colleagues. I’d much rather do that than have my colleagues stand around my head stone and talk about what I could have or should have done!
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Unfortunately, there are a lot of “unanswerable” questions in this business. Do you “go” when you really shouldn’t? Do you “stop” when you really shouldn’t? What IS the right answer? There probably isn’t a single right answer. I’ve always thought it better for me to consider what I would do under similar circumstances and, hopefully, talk about it with some of my colleagues. I’d much rather do that than have my colleagues stand around my head stone and talk about what I could have or should have done!
_______
AirRabbit
