vmca/vmcg
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vmca/vmcg
Hi guys a quick qestion, I hope that someone may be able to answer properly. if one engine fails on the ground/in the air what side would you like the wind coming from, I know you would like it to counteract the yaw but then I heard someone say about the bank angle into the live engine you would want it coming from the dead side I hope someone can clear this up
thanks..
thanks..
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Yeah you'd prefer the wind to be coming from the dead side. If you are contending with a failure and a cross wind you'll need more rudder than a failure minus a cross wind. You keep the wings level.
Dear me, is it time for the Vmcg thread, AGAIN?
GF
Seriously, a search will uncover more on the subject than a human should be allowed to know. But should anyway!
GF
Seriously, a search will uncover more on the subject than a human should be allowed to know. But should anyway!
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I don't care, and I really think it makes bugger all difference! You get an engine failure, you fly the aeroplane. You push the wrong rudder on, you die. So push the right rudder on and fly the goddam aeroplane! It's a stupid question- are you being given a choice of which engine is going to fail? And once you get airborne, it makes no goddam difference anyway, so who cares. Just concentrate on flying the goddam aeroplane and leave the theoretical claptrap to people who aren't who are mysteriously happy to expend brain calories on this useless claptrap!
Does that make my position on this fascinating question abundantly clear?
Does that make my position on this fascinating question abundantly clear?
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Just read through some old notes I had on Vmcg/Vmca. As mentioned, Vmcg is higher if you have the crosswind coming from the side of the inoperative engine. Vmca, however, doesn't vary with the direction of the crosswind as the aeroplane is already flying in the air mass.
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Look it's simple! You don't need 'old notes'. On the take off roll, you are pushing downwind rudder to stop weathercocking into wind. Therefore you do not have complete authority in rudder that side. So if an engine fails leaving you power on the other engine, that side where you will need to push even more rudder, you are prematurely restricted. If you then have mental capacity to work all that out, then you are not flying the plane properly! You don't have any option about changing which engine fails, so go with it, whichever side, and don't worry about which side is more favourable. The right answer is 'they are both unfavourable!'
Does that solve that one for the next 3 weeks?
Does that solve that one for the next 3 weeks?
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I don't care, and I really think it makes bugger all difference! You get an engine failure, you fly the aeroplane. You push the wrong rudder on, you die. So push the right rudder on and fly the goddam aeroplane! It's a stupid question- are you being given a choice of which engine is going to fail? And once you get airborne, it makes no goddam difference anyway, so who cares. Just concentrate on flying the goddam aeroplane and leave the theoretical claptrap to people who aren't who are mysteriously happy to expend brain calories on this useless claptrap!
Does that make my position on this fascinating question abundantly clear?
Does that make my position on this fascinating question abundantly clear?
In other words, you do know which engine is failed and it is not theoretical claptrap. Deletions as appropriate please Mr. Mod?
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Positioning an OEI aeroplane was NOT the question asked!
I absolutely fail to see the point of working this out and holding this nonsense in your head. There are too many other things you should have on your mind- wind direction to work out a turn before stopping on a reject, emergency turn after take-off after engine failure, getting the thing airborne at the right speeds, holding it straight, what you're going to do with the FD, do you need full power, AA- are you going to completely clear up? MSA? Then what are you going to do after all that? If you are thinking about 'it would have been better to have the engine failure on the left engine!' then you are a mental case. One of those silly theoretical questions that serves absolutely no purpose and is of no use to anybody. I believe in keeping it absolutely simple as much as possible, and this question is a useless WOT.
Scream to the Mods all you like. A search would find this theoretical stuff repeated every few months. Perhaps you'd like to make a sticky of it?
if one engine fails on the ground/in the air what side would you like the wind coming from,
Scream to the Mods all you like. A search would find this theoretical stuff repeated every few months. Perhaps you'd like to make a sticky of it?
Moderator
Some topics draw fervent responses and that is part and parcel of PPRuNe.
The realities are -
(a) certification Vmcg usually is determined for nil wind (old BCAR certifications 7kt crosswind .. which infers adverse crosswind). The concept is that of putting a low speed line in the sand with the comfort that, on most occasions, the aircraft is not operating in this region.
(b) for usual weights which result in speed schedules well above a Vmcg-limited V1, the question of crosswind is largely academic as the effect on real world Vmcg is still below the V1 speed.
(c) for critical weights (low) which relate to a low speed schedule (Vmcg-limited V1), the consideration of crosswind should be along the following lines -
(i) if you are taking off in a significant crosswind (no restrictions exist to prevent this) then, depending on which side the crosswind is from when (if) the engine fails, the effect will be stabilising (ie improves directional control) or destabilising (ie reduces directional control).
(ii) especially in the case of a moderate V1-Vr split if the wind on the day is significant you can have a situation where you are legal but likely to depart the side of the runway with an out of control aircraft in the case of a failure on the "undesirable" side. In an extreme case, the only sensible option may be to abort above V1 to remain on the runway .. with the consideration of a runway head overrun if the runway distance is limiting .. you pays your money and takes your chances .. either you die to the side of the runway or die in the overrun ...
(iii) considering normal weathercocking tendencies, in the OEI situation, a crosswind from the failed side is destabilising and, from the operating side, stabilising.
That's all very well and good .. what can you do about it ?
(a) you have no control over any failure so you can't "control" the side of the failure and crosswind. I think that this is where Rainboe's thoughts are coming from ..
(b) if the runway is distance limiting, then you can't increase the speed schedule to reduce the problem, so you either go, keeping the situation in mind regarding possible directional loss of control, depending on circumstances, or you delay until the wind reduces
(c) in the more usual case, the low speed schedule arises due to the actual TOW which, often, is only a consequence of a short range ferry situation .. ie the runway length is not limiting and you may be able to make the problem go away by increasing the speed schedule
So, how big is the potential problem ?
The real world increase in actual Vmcg in the presence of a crosswind varies with the Type. Typically you might see around half a knot increase per knot of crosswind for a twin (eg this applies to the DC9 from some test work we did many years ago) increasing to something in excess of 1 kt increase per knot of crosswind on a four-engine aircraft (according to information I have read in the past).
So, if you are in the situation AND you have the option, you might consider increasing your V1/Vr/V2 schedule by that sort of increment provided, of course, that you don't go above the limit weight speed values for the ambient temperature and H/W T/W component from the RTOW charts.
The realities are -
(a) certification Vmcg usually is determined for nil wind (old BCAR certifications 7kt crosswind .. which infers adverse crosswind). The concept is that of putting a low speed line in the sand with the comfort that, on most occasions, the aircraft is not operating in this region.
(b) for usual weights which result in speed schedules well above a Vmcg-limited V1, the question of crosswind is largely academic as the effect on real world Vmcg is still below the V1 speed.
(c) for critical weights (low) which relate to a low speed schedule (Vmcg-limited V1), the consideration of crosswind should be along the following lines -
(i) if you are taking off in a significant crosswind (no restrictions exist to prevent this) then, depending on which side the crosswind is from when (if) the engine fails, the effect will be stabilising (ie improves directional control) or destabilising (ie reduces directional control).
(ii) especially in the case of a moderate V1-Vr split if the wind on the day is significant you can have a situation where you are legal but likely to depart the side of the runway with an out of control aircraft in the case of a failure on the "undesirable" side. In an extreme case, the only sensible option may be to abort above V1 to remain on the runway .. with the consideration of a runway head overrun if the runway distance is limiting .. you pays your money and takes your chances .. either you die to the side of the runway or die in the overrun ...
(iii) considering normal weathercocking tendencies, in the OEI situation, a crosswind from the failed side is destabilising and, from the operating side, stabilising.
That's all very well and good .. what can you do about it ?
(a) you have no control over any failure so you can't "control" the side of the failure and crosswind. I think that this is where Rainboe's thoughts are coming from ..
(b) if the runway is distance limiting, then you can't increase the speed schedule to reduce the problem, so you either go, keeping the situation in mind regarding possible directional loss of control, depending on circumstances, or you delay until the wind reduces
(c) in the more usual case, the low speed schedule arises due to the actual TOW which, often, is only a consequence of a short range ferry situation .. ie the runway length is not limiting and you may be able to make the problem go away by increasing the speed schedule
So, how big is the potential problem ?
The real world increase in actual Vmcg in the presence of a crosswind varies with the Type. Typically you might see around half a knot increase per knot of crosswind for a twin (eg this applies to the DC9 from some test work we did many years ago) increasing to something in excess of 1 kt increase per knot of crosswind on a four-engine aircraft (according to information I have read in the past).
So, if you are in the situation AND you have the option, you might consider increasing your V1/Vr/V2 schedule by that sort of increment provided, of course, that you don't go above the limit weight speed values for the ambient temperature and H/W T/W component from the RTOW charts.
Rainboe,
I sincerely hope you are limiting your flying to Microsoft FliteSim, where your approach will not hurt anybody.
If you have ever been involved in (real aeroplane) flight training (which, by the sound of it is unlikely) I doubt you would take such a position. And please read all (not just this thread) of what John Tulla has to say, it's always a good theoretical starting point.
Tootle pip!!
I sincerely hope you are limiting your flying to Microsoft FliteSim, where your approach will not hurt anybody.
If you have ever been involved in (real aeroplane) flight training (which, by the sound of it is unlikely) I doubt you would take such a position. And please read all (not just this thread) of what John Tulla has to say, it's always a good theoretical starting point.
Tootle pip!!
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(ii) especially in the case of a moderate V1-Vr split if the wind on the day is significant you can have a situation where you are legal but likely to depart the side of the runway with an out of control aircraft in the case of a failure on the "undesirable" side. In an extreme case, the only sensible option may be to abort above V1 to remain on the runway .. with the consideration of a runway head overrun if the runway distance is limiting .. you pays your money and takes your chances .. either you die to the side of the runway or die in the overrun ...
So regardless of the theory I would advocate forgetting about the fact that the regulations don't care about the crosswind and always going above V1 because the stats say if you don't go you will kill.
Moderator
I sincerely hope you are limiting your flying to Microsoft FliteSim, where your approach will not hurt anybody.
Rainboe is an experienced pilot .. he can, at times, be a tad one-eyed about a subject.
I think it's more than a little risky to suggest aborting above V1.
Quite true. I'm not suggesting aborting as a desirable option .. only drawing attention to the limited circumstances situation where that may be the ONLY option available other than going off the side of the runway.
So regardless of the theory I would advocate forgetting about the fact that the regulations don't care about the crosswind and always going above V1 because the stats say if you don't go you will kill.
Subject to the limited caveat stated previously. In the event that you lose control .. and, if the circumstances are right (or should that be "wrong" ?), such can quite easily happen ... you may not have the option of continuing the takeoff.
For those who have not had the interesting opportunity to play in the Vmcg sandpit, things happen VERY quickly with the change of a few knots this way or that .. and the same thing will apply with crosswind.
Rainboe is an experienced pilot .. he can, at times, be a tad one-eyed about a subject.
I think it's more than a little risky to suggest aborting above V1.
Quite true. I'm not suggesting aborting as a desirable option .. only drawing attention to the limited circumstances situation where that may be the ONLY option available other than going off the side of the runway.
So regardless of the theory I would advocate forgetting about the fact that the regulations don't care about the crosswind and always going above V1 because the stats say if you don't go you will kill.
Subject to the limited caveat stated previously. In the event that you lose control .. and, if the circumstances are right (or should that be "wrong" ?), such can quite easily happen ... you may not have the option of continuing the takeoff.
For those who have not had the interesting opportunity to play in the Vmcg sandpit, things happen VERY quickly with the change of a few knots this way or that .. and the same thing will apply with crosswind.
Warning Toxic!
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This is annoying to me because it is absolutely not a thought in real world operations. As I pointed out, there are a hundred other things on your mind which take complete priority over this purely academic and hypothetical question. In a short haul (14 years for me) operation, you blast through these speeds in seconds. In a longhaul operation (24 years flying heavy 4 engine jets!), it is totally not a thought, of no relevance whatsoever. If I could help stop people working out this hypothetical nonsense and apply all their thoughts to correct reaction and handling of the engine failure they actually experience, rather than waste time working out the engine failure they would actually prefer to have had, I would have achieved something small and positive in the cause of sensible flying! If it takes an abrasive, unwelcome attitude to do it, I'm yer man!
And Leadsled, I wish I had time for MSFS! I'm too busy flying full time.
And Leadsled, I wish I had time for MSFS! I'm too busy flying full time.
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In these days of ATTCS (APR) it's a wonder that some smart designer hasn't come up with the opposite to mitigate some of the VMCG problem.
Along the lines of ENG FAIL - AUTO DE-RATE operative engine. I'm sure there would be a few kilos to be gained here and there by big thrust on two to get you to Vef sooner followed by a rapid de-rate to keep you on the black top when one fails.
JT, fancy banging out a few calculations?
If no one has thought of this before I'm claiming IPR here and now.
Along the lines of ENG FAIL - AUTO DE-RATE operative engine. I'm sure there would be a few kilos to be gained here and there by big thrust on two to get you to Vef sooner followed by a rapid de-rate to keep you on the black top when one fails.
JT, fancy banging out a few calculations?
If no one has thought of this before I'm claiming IPR here and now.
FEHoppy
In fact, the re-engined C-5 did just that--with a sensed loss of an outboard engine, the opposite engine sympathetically derated to 98% thrust. All calculations were done on the appropriate de-rate. It solved a Vmcg problem with increased power and met the AF performance requirements.
WRT to aborting above the programmed V1 (limited by Vmcg i.e. low TOGW), likely the runway is long enough that ASD is less than TORA and an increase in V1 not to exceed Vr is probably feasible WITH the correct Vmcg for crosswind and runway conditions. It would be unlikely to have a ASD-limited runway AND be unable to increase V1 to provide a better Vmcg margin. Unless, one is operating a "crew transporter" out of very short runway.
Three-engine ferry thread, anyone??
It is unfortunate that Vmcg information is not better understood and that the regulatory authorities treat it shabbily. Vmcg data should be available for every take-off, but especially at low gross weights. Vmcg will always be increased by crosswind and runway friction or contamination. The test types will tell one that the Vmcg test card is dicey one and subject to variations. And the pilot knows it is coming and has a excellent idea at what speed. When my company cert'd zero flap take-off data, Vmcg went up by about 12 knots, which is bit of surprise as nothing changed but the flaps.
In fact, the re-engined C-5 did just that--with a sensed loss of an outboard engine, the opposite engine sympathetically derated to 98% thrust. All calculations were done on the appropriate de-rate. It solved a Vmcg problem with increased power and met the AF performance requirements.
WRT to aborting above the programmed V1 (limited by Vmcg i.e. low TOGW), likely the runway is long enough that ASD is less than TORA and an increase in V1 not to exceed Vr is probably feasible WITH the correct Vmcg for crosswind and runway conditions. It would be unlikely to have a ASD-limited runway AND be unable to increase V1 to provide a better Vmcg margin. Unless, one is operating a "crew transporter" out of very short runway.
Three-engine ferry thread, anyone??
It is unfortunate that Vmcg information is not better understood and that the regulatory authorities treat it shabbily. Vmcg data should be available for every take-off, but especially at low gross weights. Vmcg will always be increased by crosswind and runway friction or contamination. The test types will tell one that the Vmcg test card is dicey one and subject to variations. And the pilot knows it is coming and has a excellent idea at what speed. When my company cert'd zero flap take-off data, Vmcg went up by about 12 knots, which is bit of surprise as nothing changed but the flaps.
Moderator
Unless, one is operating a "crew transporter" out of very short runway.
This sort of problem is where I developed a training interest in Vmcg handling concerns .. some years ago I did a contract job as a sim instructor for a particular airline. Said airline routinely operated the 737 to high overspeed schedules for sensible reasons.
However, they had one short sector at ferry weight .. used min speed schedules on the line but never trained in the sim for it .. ie all the training was at high overspeed (read = walk in the park takeoff failures).
I though this to be a little deficient in training philosophy.
On one sim rotation I was doing a proficiency check on a couple of checkies and, at the end of the session, offered a looksee at the problem. Wide eyes and heightened interest after the first attempt. Couple of goes and the boys had it all under control .. but the point was made quite clearly that a problem existed.
The handling problem, which the majority of civilian pilots never see, is that the responses vary slowly as failure speed is reduced toward Vmcg/Vmca and then, in the last couple of knots, it all goes pear shaped very rapidly.
Sim training has the caveat of how well the box models the reality but, for the operater above, their box was quite realistic in its handling responses.
Suffice it to say that upgrade folks trained by our little group had absolutely no problem with their sim checkout handling skills.
Vmcg data should be available for every take-off
For the civil line pilot, Vmcg is the exception concern for normal ops and, with the worst case approach to the certification definition, it probably is a reasonable risk case to emphasis awareness rather than routine competence. However, awareness should include some exposure in a realistic sim environment and this, I suggest, probably is a significant deficiency in the system.
Vmcg went up by about 12 knots, which is bit of surprise as nothing changed but the flaps
Depends on which effects are significant on the particular Type.
AUTO DE-RATE operative engine
I can't see any engineering reason why not and, although I wasn't aware of it before, GF's C5 story is illustrative. However, the certification basis is heavily wrapped up in no reduction to thrust settings so there would have to be some soul searching in the Regulatory areas to permit such a thing.
My take on the problem for civil operations is that the risk overall is not high due to exposure rates. However, I do champion the desirability of the line pilot having some knowledge and appreciation of the problem.
I can relate an anecdote along the lines that, a long time ago, I was one of the doubting Thomases ... until I participated in my first trials involving Vmcg investigation ... instant Pauline style of conversion ... I was operating the long lens video recording at the runway head ... it is eye-opening to observe the subject aircraft just disappear out of the side of the viewfinder ....
JT, fancy banging out a few calculations?
with an engine/airframe model, the sums are not overly onerous and follow the usual models.
It is the most asked question at Ryanair Interview
Does that mean those folks read Tech Log ? Actually, the sim they purchased from ANZ some years ago modelled the failure quite nicely .. I was the bunny grabbed to do the pushing and pulling late one night when the software was upgraded for the revised rudder model and the box went from being quite benignly unrealistic to "interesting"
This sort of problem is where I developed a training interest in Vmcg handling concerns .. some years ago I did a contract job as a sim instructor for a particular airline. Said airline routinely operated the 737 to high overspeed schedules for sensible reasons.
However, they had one short sector at ferry weight .. used min speed schedules on the line but never trained in the sim for it .. ie all the training was at high overspeed (read = walk in the park takeoff failures).
I though this to be a little deficient in training philosophy.
On one sim rotation I was doing a proficiency check on a couple of checkies and, at the end of the session, offered a looksee at the problem. Wide eyes and heightened interest after the first attempt. Couple of goes and the boys had it all under control .. but the point was made quite clearly that a problem existed.
The handling problem, which the majority of civilian pilots never see, is that the responses vary slowly as failure speed is reduced toward Vmcg/Vmca and then, in the last couple of knots, it all goes pear shaped very rapidly.
Sim training has the caveat of how well the box models the reality but, for the operater above, their box was quite realistic in its handling responses.
Suffice it to say that upgrade folks trained by our little group had absolutely no problem with their sim checkout handling skills.
Vmcg data should be available for every take-off
For the civil line pilot, Vmcg is the exception concern for normal ops and, with the worst case approach to the certification definition, it probably is a reasonable risk case to emphasis awareness rather than routine competence. However, awareness should include some exposure in a realistic sim environment and this, I suggest, probably is a significant deficiency in the system.
Vmcg went up by about 12 knots, which is bit of surprise as nothing changed but the flaps
Depends on which effects are significant on the particular Type.
AUTO DE-RATE operative engine
I can't see any engineering reason why not and, although I wasn't aware of it before, GF's C5 story is illustrative. However, the certification basis is heavily wrapped up in no reduction to thrust settings so there would have to be some soul searching in the Regulatory areas to permit such a thing.
My take on the problem for civil operations is that the risk overall is not high due to exposure rates. However, I do champion the desirability of the line pilot having some knowledge and appreciation of the problem.
I can relate an anecdote along the lines that, a long time ago, I was one of the doubting Thomases ... until I participated in my first trials involving Vmcg investigation ... instant Pauline style of conversion ... I was operating the long lens video recording at the runway head ... it is eye-opening to observe the subject aircraft just disappear out of the side of the viewfinder ....
JT, fancy banging out a few calculations?
with an engine/airframe model, the sums are not overly onerous and follow the usual models.
It is the most asked question at Ryanair Interview
Does that mean those folks read Tech Log ? Actually, the sim they purchased from ANZ some years ago modelled the failure quite nicely .. I was the bunny grabbed to do the pushing and pulling late one night when the software was upgraded for the revised rudder model and the box went from being quite benignly unrealistic to "interesting"
Rainboe is an experienced pilot .. he can, at times, be a tad one-eyed about a subject.
So he may be, but so am I, and it doesn't hurt to have in the back of your mind what an aircraft is going to do (particularly with a Vmcg limited V1) if you do have an engine failure of the "wrong" engine in a crosswind -- on every T/O -- particularly if you work for an airline that, as a matter of policy, favours "low" V1s, and unbalanced field length T/0s,ie; they agree with the Boeing philosophy: "Our airplanes go better than they stop" --- and ain't the truth, even if their "stopping" has improved with each successive model.
If you haven't at least mentally pre-briefed, the fact that the aeroplane (in the adverse case at the limits) at V1 + will leave the centerline will come as an added "surprise" on top of the failure, if this is interpreted as a loss of control, and an abort is attempted post V1, disaster is a certainty.
Is this too theoretical?? No, it has happened, they did, and it was. Even in a lesser accident, one well known airline in our part of the world wrote off an (4 engine) aeroplane with a simple engine failure approaching 100kt. The only reason a US operator of the same type, in almost identical circumstances didn't, was paved areas and ice off the runway, the U/C did not collapse in the ground loop, "just" scraped two pods and shredded the tyres. 'tis all in the history books.
You mention later, the behavior of an aircraft at light weights (V1 speeds close to Vmcg) compared to "heavy" weights. Then there is the little matter of what is actually accounted for in T/O calculations. Boeing will sell you ( as an option) a whole set of figures accounting for the directional effects of spoiler rise (increase in Vmcg) in a crosswind, but I have yet to meet other than one single airline that has used it. For most, the performance (read payload) penalty makes it a non-starter, unless it's State mandated, and I know of no State that does.
A close examination of the long term statistics for "critical" aborts is most instructive, don't worry too much about the runway length, because the greater probability is that you will go off the side --- Vmcg again.
Rainbow is at least partially right about one thing, it doesn't matter much what the actual reason is, that you went gardening in an abort, but gardening as a full time occupation would loom soon after.
Just as well critical aborts are very rare, engine failure caused even rarer, because I don't think enough attention is given to the background. It might never happen to you in a whole career, but it does happen.
In one particular airline (where an abort is P1 only, regardless of pilot flying) a very interesting series of sim. cyclics were put up, largely because it became very obvious that there was widespread misconception about the real (certification) meaning of V1 -- and far from confined to this airline.
The exercise (no jeopardy) used a short runaway, not level, wet with varying crosswinds, with engine failures ("right" and "wrong" side) at various stages of T/O, from 80kt. through to Vr. It was a well known "real" runway, not something invented for the exercise. "Wet runway" V1 or otherwise unbalanced (as allowed in Performance Calcs.) V1s were used --- all as would happen in the real world, ie; Vmcg problems were never going to be far away.
At least in this case, the absorbed results showed as very significant changes to simulator exercises, both initial and re-current --- but the most important outcome was a newfound respect for the need to be able to know how to "fly the aeroplane".
Tootle pip!!
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I suspect that we are more or less aligned in our thoughts although, perhaps, viewing the problem from routine line flying versus certification compared to reality viewpoints.
Our airplanes go better than they stop ..
Perhaps other than for the 727 modded with nosewheel brakes we would all more or less concur with that view
the aeroplane .... will leave the centerline
absolutely. The certification Vmcg will be determined by the failure speed at which this controllable deviation equals the permitted certification limit.
if this is interpreted as a loss of control
not at all. This is the to be expected aircraft response to a failure on the ground during takeoff. One always expects a deviation from centreline even if many pilots opine that this aircraft or that runs like it’s on rails during a normal proficiency check failure .... Loss of control, in this situation, means going off the side and the pilot can't do a thing about it unless he/she does something unusual ...
Boeing will sell you (as an option) a whole set of figures accounting for the directional effects of spoiler rise ...
noted. Boeing, like any other OEM, will sell you anything they can talk you into buying. Many of us were bemused when Ansett took the computer option on the 727LR (PDCS, if my memory is correct ?) .. now, someone did a good selling job along the way there ...
A close examination of the long term statistics for "critical" aborts is most instructive, .... the greater probability is that you will go off the side --- Vmcg again.
this, I suggest may relate more to the demonstrable mismatch of some larger aircraft to the ICAO geometric runway width limits ... CJF et al came up with some interesting sim results as part of the workup to the runway width testing requirements in Australia (quite some years ago, now)
that you went gardening in an abort, but gardening as a full time occupation would loom soon after.
probably not for me to second guess the outcome of an enquiry. However, the situation still remains that, in the circumstances I am describing, the crew is just along for the ride and the aircraft's gyrations will become (in the limit) quite independent of crew actions if those actions are intending to continue the takeoff.
I don't think enough attention is given to the background
absolutely concur. Which is why we like to see this (and other not so commonplace on the line) topics come up for the educational exposure value for the newchums.
a very interesting series of sim. cyclics were put up
exactly what we believe should be routine training exposure for crews .. at the very least, during endorsement training. My exercises on the 737 were of similar philosophy. Looking at your location and presuming an operator, I would see that exercise possibly coming from the lineage of a particular early operations engineer who had a reasonable operational background.
At least in this case, the absorbed results showed as very significant changes to simulator exercises, both initial and re-current
I’m not at all surprised to hear that ...
Our airplanes go better than they stop ..
Perhaps other than for the 727 modded with nosewheel brakes we would all more or less concur with that view
the aeroplane .... will leave the centerline
absolutely. The certification Vmcg will be determined by the failure speed at which this controllable deviation equals the permitted certification limit.
if this is interpreted as a loss of control
not at all. This is the to be expected aircraft response to a failure on the ground during takeoff. One always expects a deviation from centreline even if many pilots opine that this aircraft or that runs like it’s on rails during a normal proficiency check failure .... Loss of control, in this situation, means going off the side and the pilot can't do a thing about it unless he/she does something unusual ...
Boeing will sell you (as an option) a whole set of figures accounting for the directional effects of spoiler rise ...
noted. Boeing, like any other OEM, will sell you anything they can talk you into buying. Many of us were bemused when Ansett took the computer option on the 727LR (PDCS, if my memory is correct ?) .. now, someone did a good selling job along the way there ...
A close examination of the long term statistics for "critical" aborts is most instructive, .... the greater probability is that you will go off the side --- Vmcg again.
this, I suggest may relate more to the demonstrable mismatch of some larger aircraft to the ICAO geometric runway width limits ... CJF et al came up with some interesting sim results as part of the workup to the runway width testing requirements in Australia (quite some years ago, now)
that you went gardening in an abort, but gardening as a full time occupation would loom soon after.
probably not for me to second guess the outcome of an enquiry. However, the situation still remains that, in the circumstances I am describing, the crew is just along for the ride and the aircraft's gyrations will become (in the limit) quite independent of crew actions if those actions are intending to continue the takeoff.
I don't think enough attention is given to the background
absolutely concur. Which is why we like to see this (and other not so commonplace on the line) topics come up for the educational exposure value for the newchums.
a very interesting series of sim. cyclics were put up
exactly what we believe should be routine training exposure for crews .. at the very least, during endorsement training. My exercises on the 737 were of similar philosophy. Looking at your location and presuming an operator, I would see that exercise possibly coming from the lineage of a particular early operations engineer who had a reasonable operational background.
At least in this case, the absorbed results showed as very significant changes to simulator exercises, both initial and re-current
I’m not at all surprised to hear that ...
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To J_T
Mind if I interrupt with a question, Captain? 
May I ask you the connection between both segments of your post in bold?
I kinda got lost there and I want to clear my mind on this subject...
Am I correct understanding such statement as "engine failure below V1 (just a few knots, certainly not below the high speed part of the takeoff) plus a "moderate V1/Vr split", would make the aircraft difficult to control due to the low V1 (very close to Vmcg?) and the need to accelerate on one engine to Vr while struggling with the controls to keep the aircraft on a "proper" path"?
Or am I missing something?
Thanks in advance
especially in the case of a moderate V1-Vr split if the wind on the day is significant you can have a situation where you are legal but likely to depart the side of the runway with an out of control aircraft in the case of a failure on the "undesirable" side.
I kinda got lost there and I want to clear my mind on this subject...
Am I correct understanding such statement as "engine failure below V1 (just a few knots, certainly not below the high speed part of the takeoff) plus a "moderate V1/Vr split", would make the aircraft difficult to control due to the low V1 (very close to Vmcg?) and the need to accelerate on one engine to Vr while struggling with the controls to keep the aircraft on a "proper" path"?
Or am I missing something?
Thanks in advance