Air North Brasilia Crash in Darwin (Merged)
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Just a little off the subject for a moment. Why is that a young mans tragic death in the surf here on the Gold Coast has been in the media for some days and yet two educated, highly trained tax paying family men who lost their lives in a rather large aircraft barely rate a mention. This does not deride the young man that died, but to question is a pilots life less than a young ironmans, what makes this young fella so newsworthy, yet a young pilot with a family, rates little. I would much prefer that there had to be no coverage on either accident, but sadly there is, but living here on the Gold Coast its is all we have heard about, absolutely nothing on this tragic affair in DRW.
Funny you say that, teresa green. I can't recall seeing any mention of it in the media here either.
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Witnesses report that the aircraft had just got airborne and then there was a rapid roll to the left. I have never briefed during my takeoff safety brief for a loss of control on departure due to Autofx failure and possible subsequent Vmca departure
I don't suggest that one ought to brief on every unlikely oddball eventuality .. the aircraft would need then to return to the ramp for a top up.
However, and especially for the commander, one ought to have spent a lot of time in the armchair at home, over a coffee or fine wine, contemplating this and that eventuality and what one might be able to do to reduce the severity of the outcome consequences. The bird IS going to get bent and people ARE going to die. Better to have some survive rather than none ? What we don't need is for the commander to have his/her first thoughts on the subject at the time he/she is faced with the problem ... very likely those thoughts may be the last he/she does have.
A fine read in this regard is Al Haines' presentation on the Sioux City mishap. The text and video is readily available on the net and is well worth the neophyte's time over a coffee or ten.
More importantly, SOPs cover the routine, not the out of left field. On occasion, the commander is called upon to make a VERY rapid assessment/decision and implement it in the interests of minimising the losses during the accident.
Departure from controlled flight in a critical situation is just such a circumstance .. better, I suggest, to die trying .. and with a chance of surviving, than just sitting there and going along for the ride into guaranteed oblivion.
Another is the Vmcg departure from controlled flight (say, in a strongish adverse crosswind) .. the aircraft IS out of control and the takeoff HAS to be abandoned even though above V1 .. There is no time to have a reflective consideration about it, the situation requires immediate and decisive action.
I'm sure we can all dream up a list of similar scenarios ?
I see some raised eyebrows in respect of Centaurus' post. Now, I have known this (very experienced) pilot for most of my working life. He has a great knowledge of performance and so forth. Implicit in his comment is the need to be aware of how close the speed schedule is to min speed (ie either a Vmcg/Vmca limited takeoff).
I don't suggest that one ought to brief on every unlikely oddball eventuality .. the aircraft would need then to return to the ramp for a top up.
However, and especially for the commander, one ought to have spent a lot of time in the armchair at home, over a coffee or fine wine, contemplating this and that eventuality and what one might be able to do to reduce the severity of the outcome consequences. The bird IS going to get bent and people ARE going to die. Better to have some survive rather than none ? What we don't need is for the commander to have his/her first thoughts on the subject at the time he/she is faced with the problem ... very likely those thoughts may be the last he/she does have.
A fine read in this regard is Al Haines' presentation on the Sioux City mishap. The text and video is readily available on the net and is well worth the neophyte's time over a coffee or ten.
More importantly, SOPs cover the routine, not the out of left field. On occasion, the commander is called upon to make a VERY rapid assessment/decision and implement it in the interests of minimising the losses during the accident.
Departure from controlled flight in a critical situation is just such a circumstance .. better, I suggest, to die trying .. and with a chance of surviving, than just sitting there and going along for the ride into guaranteed oblivion.
Another is the Vmcg departure from controlled flight (say, in a strongish adverse crosswind) .. the aircraft IS out of control and the takeoff HAS to be abandoned even though above V1 .. There is no time to have a reflective consideration about it, the situation requires immediate and decisive action.
I'm sure we can all dream up a list of similar scenarios ?
I see some raised eyebrows in respect of Centaurus' post. Now, I have known this (very experienced) pilot for most of my working life. He has a great knowledge of performance and so forth. Implicit in his comment is the need to be aware of how close the speed schedule is to min speed (ie either a Vmcg/Vmca limited takeoff).
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Centaurus
Hmmmm well I hope you briefed your F/O accordingly... or that could have resulted in some very ugly incidents...
Better to just artificially reduce the V1 if you are going to be doing stuff like that.
from 15 knots below V1 I was going to continue the take off and sort the problem in the air. Might have been procedurally illegal but that's the way I saw it.
Better to just artificially reduce the V1 if you are going to be doing stuff like that.
To wit - V 1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance.
FAR § 25.107 Takeoff speeds.
(a) V1must be established in relation to VEF as follows:
(1) VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under §25.149(e).
(2) V1, in terms of calibrated airspeed, is selected by the applicant; however, V1may not be less than VEF plus the speed gained with critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognizes and reacts to the engine failure, as indicated by the pilot's initiation of the first action (e.g., applying brakes, reducing thrust, deploying speed brakes) to stop the airplane during accelerate-stop tests.
The decision to abort is made prior to reaching V1, because the first physical action of applying retardation has to occur at V1. The hard part is at what speed below V1 do you pick as the decision point to allow you to react and commence retardation at V1. Rate of acceleration would play a major role I would imagine. And whether you are bright eyed and bushy tailed, against the commencement of the last sector in a very long and fatiguing day.
Last edited by Brian Abraham; 26th Mar 2010 at 16:19. Reason: Add FAR 25.107
teresa green - I have heard almost nothing, even though Air North serves OOL. I agree we should all be paying respect to the 2 lives lost but then again I am sure are all wishing the best for the airline's future. A media beat up could easily destroy a reputation
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A media beat up could easily destroy a reputation
That's why I hold my opinion until the facts are presented!
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Brian Abraham
You missed the second part of the FAA definition (not that it applies in Australia anyway):
"V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance."
The point being that if you decide to go before V1, you can't be assured of obstacle clearance.
The decision to abort can be taken at any speed, however the decision to go (from a regulatory standpoint) is taken at V1. That is why most operators have an SOP that states the PF (or captain) has his hand on the power levers until V1, at which point they are moved off the power levers as an abort is no longer intended (although it could still be possible, but you risk shredding the tyres and/or overheating the brakes).
V1 can be reduced, in fact it often is when runway length, condition, or the net takeoff path demands it.
Some airlines operate to a Decision Speed instead of V1, typically around 8 kts below V1 for a 747.
Whatever the case, V1 must not be less than VMCG, VR must be not less than 1.05 VMCA. V1 must not be greater than VR.
john_tullamarine
The danger of what Centaurus is saying (and it IS dangerous) is that it could lead to confusion on the flight deck at a critical moment; It doesn't take either field length of obstacle clearance into account - for example, on a contaminated runway where there would be significant reduction to the acceleration to Vr and a consequently extended ground run; it contradicts the company SOPs; and would almost certainly have significant repercussions to the pilot and the company if there was an incident related to a "go" decision prior to V1.
Yes, the speeds are close, and the engine failure profile has to be flown accurately. However, there is sufficient "wiggle room" in the speeds to give a reasonable assurance of safety - the certification process makes sure of that.
In this phase of flight, everyone needs to know exactly what the other is doing, and not have any surprises thrown at them. Making up your own procedures is just asking for it, it doesn't matter how old or experienced you might be. Centaurus may know more than the aircraft manufacturers, certification test pilots, and the regulatory authorities - but I doubt it.
Well most of what abnormal/non-normal SOPs cover isn't really routine, most pilots only see the more arcane abnormals/non-normals once every 3 years or so.
Having said that, when I was flying turboprops, a wise old training captain told me that I should always be prepared to just close the power levers and put it down straight ahead - better to have some control than none at all. He was right, particularly in the older turboprops, which can be pretty marginal. As far as I am concerned, losing control is the absolute enemy.
Vmcg doesn't apply if you are flying... it's one or the other (ie Vmca if in the air or Vmcg if the wheels are on the ground).
But yes, there are times when flat tyres and melted brakes are better than going flying!
There was an interesting incident several years ago, involving a HS748 that had a catastrophic engine failure on takeoff (just after rotation) that resulted in a major fire. The aircraft was airborne for 27 seconds before the captain re-landed the aircraft and went off the end of the runway at about 60kts. The nose gear collapsed, but everyone got out OK.
The report exonerated the captain, but the company basically crucified him for disobeying SOPs.
Air Accidents Investigation: 3/2001 G-OJEM
You missed the second part of the FAA definition (not that it applies in Australia anyway):
"V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance."
The point being that if you decide to go before V1, you can't be assured of obstacle clearance.
The decision to abort can be taken at any speed, however the decision to go (from a regulatory standpoint) is taken at V1. That is why most operators have an SOP that states the PF (or captain) has his hand on the power levers until V1, at which point they are moved off the power levers as an abort is no longer intended (although it could still be possible, but you risk shredding the tyres and/or overheating the brakes).
V1 can be reduced, in fact it often is when runway length, condition, or the net takeoff path demands it.
Some airlines operate to a Decision Speed instead of V1, typically around 8 kts below V1 for a 747.
Whatever the case, V1 must not be less than VMCG, VR must be not less than 1.05 VMCA. V1 must not be greater than VR.
john_tullamarine
The danger of what Centaurus is saying (and it IS dangerous) is that it could lead to confusion on the flight deck at a critical moment; It doesn't take either field length of obstacle clearance into account - for example, on a contaminated runway where there would be significant reduction to the acceleration to Vr and a consequently extended ground run; it contradicts the company SOPs; and would almost certainly have significant repercussions to the pilot and the company if there was an incident related to a "go" decision prior to V1.
Yes, the speeds are close, and the engine failure profile has to be flown accurately. However, there is sufficient "wiggle room" in the speeds to give a reasonable assurance of safety - the certification process makes sure of that.
In this phase of flight, everyone needs to know exactly what the other is doing, and not have any surprises thrown at them. Making up your own procedures is just asking for it, it doesn't matter how old or experienced you might be. Centaurus may know more than the aircraft manufacturers, certification test pilots, and the regulatory authorities - but I doubt it.
More importantly, SOPs cover the routine, not the out of left field. On occasion, the commander is called upon to make a VERY rapid assessment/decision and implement it in the interests of minimising the losses during the accident.
Having said that, when I was flying turboprops, a wise old training captain told me that I should always be prepared to just close the power levers and put it down straight ahead - better to have some control than none at all. He was right, particularly in the older turboprops, which can be pretty marginal. As far as I am concerned, losing control is the absolute enemy.
the Vmcg departure from controlled flight (say, in a strongish adverse crosswind)
But yes, there are times when flat tyres and melted brakes are better than going flying!
There was an interesting incident several years ago, involving a HS748 that had a catastrophic engine failure on takeoff (just after rotation) that resulted in a major fire. The aircraft was airborne for 27 seconds before the captain re-landed the aircraft and went off the end of the runway at about 60kts. The nose gear collapsed, but everyone got out OK.
The report exonerated the captain, but the company basically crucified him for disobeying SOPs.
Air Accidents Investigation: 3/2001 G-OJEM
Moderator
The point being that if you decide to go before V1, you can't be assured of obstacle clearance.
.. or TODR, TORR, loss of directional control, etc ...
V1 can be reduced, in fact it often is when runway length, condition, or the net takeoff path demands it.
.. such has, as an implicit requirement, compliance with all the rules. The normal procedures are not capricious but, rather, are quite deliberate in their bases.
The danger of what Centaurus is saying
I'm neither agreeing/disagreeing with Centaurus.
He was expressing his own philosophical take on the matter as a greybeard (actually he doesn't have a beard, but never mind) - his level of experience warrants a hearing regardless of whether you might agree or disagree with the sentiments so expressed.
As a general rule, adherence to SOP is the preference if for no other reason than that it is a sensible risk based approach to the routine problems of flying.
The point of the discussion is that, sometimes, when problems come out of left field and the situation is outside the certification fence-around-the-paddock ... SOPs don't have the answer and the commander is called upon to step up to the mark and earn his/her paypacket for the year in the next few seconds. If the outcome is successful, we pat him/her on the back, if not, and quite unfairly in many cases, we tend to hang the pilot's integrity/competence. Part and parcel of being "the commander".
However, there is sufficient "wiggle room" in the speeds to give a reasonable assurance of safety - the certification process makes sure of that.
I'm a little uncomfortable with that as a broad statement. For the accel-stop manoeuvre (and that is the principal concern with V1) there is very little fudge factor (wiggle room, if you prefer) for accel-stop. This is especially so for the earlier aircraft .. indeed FAR 25 A/L 42, which introduced the requirement for a 2-second delay, recognised just this concern.
Centaurus may know more than the aircraft manufacturers, certification test pilots, and the regulatory authorities - but I doubt it.
to give Centaurus his due, he is quite SOP-oriented so we can take your comment in the underlying spirit it was made.
Well most of what abnormal/non-normal SOPs cover isn't really routine, most pilots only see the more arcane abnormals/non-normals once every 3 years or so.
and, with increasing engine and general system reliability, some never are called upon to step up to the mark .. surely a good thing overall for the customers.
a wise old training captain told me that I should always be prepared to just close the power levers and put it down straight ahead
precisely my point but one perhaps overlooked by the blinkered SOP adherents ?
Vmcg doesn't apply if you are flying... it's one or the other (ie Vmca if in the air or Vmcg if the wheels are on the ground).
indeed .. if I gave the impression that I was suggesting otherwise then that was only a consequence of my poor literary skills - perhaps the reference to "departure from controlled flight" which has a specific meaning and covers situations on the ground as well as in flight.
However, it is very important to keep in mind that any takeoff at low weight, with min speed schedules, can bite the pilot hard ... either due to a Vmcg OR Vmca departure ... if he/she is a bit hamfisted. Indeed, if the pilot has not been trained for such takeoffs, then the gyrations can be very surprising ...
I can recall a training contract with a particular airline which generally operated to higher overspeed (improved performance for the Airbus folk) procedures. When I had some of the folk have a look at the other end of the spectrum the results opened a few eyes. Indeed, most involved needed several goes to get the beast under control. Not a problem, per se, but emphasised the need for specific training in low speed schedule engine failures ... quite a different sort of beast to the "normal" EFATO licence renewal sequence at forward/mid CG and higher weights/speed schedules. The reality is that the directional control thing ramps up very rapidly in the last few knots of V1 reduction and a comparatively tame aircraft can become a bit of a tiger.
But yes, there are times when flat tyres and melted brakes are better than going flying!
or, indeed, a bent aeroplane in the overrun .. but with plenty of survivors.
The nose gear collapsed, but everyone got out OK.
my philosophical point precisely.
.. or TODR, TORR, loss of directional control, etc ...
V1 can be reduced, in fact it often is when runway length, condition, or the net takeoff path demands it.
.. such has, as an implicit requirement, compliance with all the rules. The normal procedures are not capricious but, rather, are quite deliberate in their bases.
The danger of what Centaurus is saying
I'm neither agreeing/disagreeing with Centaurus.
He was expressing his own philosophical take on the matter as a greybeard (actually he doesn't have a beard, but never mind) - his level of experience warrants a hearing regardless of whether you might agree or disagree with the sentiments so expressed.
As a general rule, adherence to SOP is the preference if for no other reason than that it is a sensible risk based approach to the routine problems of flying.
The point of the discussion is that, sometimes, when problems come out of left field and the situation is outside the certification fence-around-the-paddock ... SOPs don't have the answer and the commander is called upon to step up to the mark and earn his/her paypacket for the year in the next few seconds. If the outcome is successful, we pat him/her on the back, if not, and quite unfairly in many cases, we tend to hang the pilot's integrity/competence. Part and parcel of being "the commander".
However, there is sufficient "wiggle room" in the speeds to give a reasonable assurance of safety - the certification process makes sure of that.
I'm a little uncomfortable with that as a broad statement. For the accel-stop manoeuvre (and that is the principal concern with V1) there is very little fudge factor (wiggle room, if you prefer) for accel-stop. This is especially so for the earlier aircraft .. indeed FAR 25 A/L 42, which introduced the requirement for a 2-second delay, recognised just this concern.
Centaurus may know more than the aircraft manufacturers, certification test pilots, and the regulatory authorities - but I doubt it.
to give Centaurus his due, he is quite SOP-oriented so we can take your comment in the underlying spirit it was made.
Well most of what abnormal/non-normal SOPs cover isn't really routine, most pilots only see the more arcane abnormals/non-normals once every 3 years or so.
and, with increasing engine and general system reliability, some never are called upon to step up to the mark .. surely a good thing overall for the customers.
a wise old training captain told me that I should always be prepared to just close the power levers and put it down straight ahead
precisely my point but one perhaps overlooked by the blinkered SOP adherents ?
Vmcg doesn't apply if you are flying... it's one or the other (ie Vmca if in the air or Vmcg if the wheels are on the ground).
indeed .. if I gave the impression that I was suggesting otherwise then that was only a consequence of my poor literary skills - perhaps the reference to "departure from controlled flight" which has a specific meaning and covers situations on the ground as well as in flight.
However, it is very important to keep in mind that any takeoff at low weight, with min speed schedules, can bite the pilot hard ... either due to a Vmcg OR Vmca departure ... if he/she is a bit hamfisted. Indeed, if the pilot has not been trained for such takeoffs, then the gyrations can be very surprising ...
I can recall a training contract with a particular airline which generally operated to higher overspeed (improved performance for the Airbus folk) procedures. When I had some of the folk have a look at the other end of the spectrum the results opened a few eyes. Indeed, most involved needed several goes to get the beast under control. Not a problem, per se, but emphasised the need for specific training in low speed schedule engine failures ... quite a different sort of beast to the "normal" EFATO licence renewal sequence at forward/mid CG and higher weights/speed schedules. The reality is that the directional control thing ramps up very rapidly in the last few knots of V1 reduction and a comparatively tame aircraft can become a bit of a tiger.
But yes, there are times when flat tyres and melted brakes are better than going flying!
or, indeed, a bent aeroplane in the overrun .. but with plenty of survivors.
The nose gear collapsed, but everyone got out OK.
my philosophical point precisely.
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Just a little off the subject for a moment. Why is that a young mans tragic death in the surf here on the Gold Coast has been in the media for some days and yet two educated, highly trained tax paying family men who lost their lives in a rather large aircraft barely rate a mention. This does not deride the young man that died, but to question is a pilots life less than a young ironmans, what makes this young fella so newsworthy, yet a young pilot with a family, rates little. I would much prefer that there had to be no coverage on either accident, but sadly there is, but living here on the Gold Coast its is all we have heard about, absolutely nothing on this tragic affair in DRW
It is interesting, living in Brissy, the young lifesaver has made the news everyday since the very sad incident, WRT the sad loss in Darwin, have had to hunt for any media, I can only recall it making the TV news on the day and the day after and that was on the ABC.
Sadly I can only put it down to a couple of things, Firstly: the Lifesaver was a volunteer, and it is now being revealed that he had thoughts about not competing in that event, and Secondly, our dear friends in Darwin didn't have 18 passengers behind them.
Regards,
It is interesting, living in Brissy, the young lifesaver has made the news everyday since the very sad incident, WRT the sad loss in Darwin, have had to hunt for any media, I can only recall it making the TV news on the day and the day after and that was on the ABC.
Sadly I can only put it down to a couple of things, Firstly: the Lifesaver was a volunteer, and it is now being revealed that he had thoughts about not competing in that event, and Secondly, our dear friends in Darwin didn't have 18 passengers behind them.
Regards,
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It's most unfortunate Dashunder that the media whores will completely disregard what people like us see as newsworthy in favour of something that is likely to sell more product.
A contributing factor, I'm guessing, is that Darwin is a long way from anywhere, and then the point you make about no pax is also relevant.
A contributing factor, I'm guessing, is that Darwin is a long way from anywhere, and then the point you make about no pax is also relevant.
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Centaurus it seems, has read the content of several articles sourced from Boeing and the FAA, regarding the GO / NO GO, decision making process. (Happy to have provided the link, all those years ago
)
Boeing Aero Magazine - Rejected Take-Off Studies
FAA - Take-Off Safety Training Aid
)Boeing Aero Magazine - Rejected Take-Off Studies
FAA - Take-Off Safety Training Aid
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remoak
Sometimes indeed it is....
A good recent example of when it was a good decision to stop, even though it was after V1 and Vr, was the ANZ 777 RTO at Narita in Feb.
On rotation the PF found that the controls wouldn’t budge. Even though it was well after Vr the Capt then rejected the TO bursting about 12 tyres but managed to pull her up by the RW end.
It was found that the Auto pilot had inadvertently been selected on prior to TO.
But yes, there are times when flat tyres and melted brakes are better than going flying!
Sometimes indeed it is....
A good recent example of when it was a good decision to stop, even though it was after V1 and Vr, was the ANZ 777 RTO at Narita in Feb.
On rotation the PF found that the controls wouldn’t budge. Even though it was well after Vr the Capt then rejected the TO bursting about 12 tyres but managed to pull her up by the RW end.
It was found that the Auto pilot had inadvertently been selected on prior to TO.
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The most important part of that text in Brian Abraham's post being the last paragraph in smaller letters... which is why committing to "go" before V1 is not a smart idea at all. I don't see anything in any of those documents that endorses a "go" decision before V1, other than from the point of view that you are always "going" unless you consciously decide to abort. All of the copied text above is making the point that you shouldn't try an RTO after V1, that you should have decided by then - in other words, it's talking about the danger of a LATE decision. The Evergreen procedure simply uses a reduced V1 and accepts the slightly degraded 1st and 2nd segment climb performance - but it still calls it V1.
The danger of what Centaurus was suggesting is that is seems to be a completely arbitrary speed that he decides on, apparently without reference to any performance data, or to his First Officer. The danger isn't so much the speed itself (although a 15kt reduction could put you in the trees), but the apparent lack of CRM and the very real likelihood of considerable confusion on the flight deck at a critical time.
I've met plenty of "graybeards" who made up their own SOPs, the whole point of modern CRM/Human Factors training is to eliminate that sort of thing. Now that I'm approaching "graybeard" status myself, I fully understand WHY Centaurus might want to do what he is suggesting, but, frankly, the days of "old school" command techniques are over.
john_tullamarine
Yes, absolutely, and it would be interesting to hear further from him on why he does what he does, and how he reconciles it with the stuff I have suggested. Having a decent debate on the subject can only be good.
Absolutely, and I have had several occasions like that during my years in command. Sometimes you are just hanging on and praying... other times you get a flash of right-field inspiration.
Actually I was referring more to controllability issues, remember the original issue was the small gap between V1 and minimum controllability speeds.
The relationship between V1 and accel-stop is an utter fudge anyway. When I was operating the 146 above the arctic circle, we went into plenty of runways that technically should have complied with all the requirements, but which you absolutely knew were too slimy for the crew to have much chance if they had to abort, particularly as the 146 is completely dependent on wheel brakes. V1 on those runways should have been about 50 kts. Another good example is the last third of 15 at Birmingham in the UK, technically the same as the rest of the runway but known to be bumpy and slippery in wet conditions.
True, but in my experience, very few pilots ever manage to keep the speed down near a lower limiting speed anyway. There aren't many turboprops that don't have the power to either climb away well, or speed up when very light. We always taught our guys to hold the achieved speed as long as they were climbing, and this was rarely less than Vr + 20kts or so. If you try and hold it at V2 and initiate a steep-ish climb, you WILL have trouble unless you are ace of the base.
The danger of what Centaurus was suggesting is that is seems to be a completely arbitrary speed that he decides on, apparently without reference to any performance data, or to his First Officer. The danger isn't so much the speed itself (although a 15kt reduction could put you in the trees), but the apparent lack of CRM and the very real likelihood of considerable confusion on the flight deck at a critical time.
I've met plenty of "graybeards" who made up their own SOPs, the whole point of modern CRM/Human Factors training is to eliminate that sort of thing. Now that I'm approaching "graybeard" status myself, I fully understand WHY Centaurus might want to do what he is suggesting, but, frankly, the days of "old school" command techniques are over.
john_tullamarine
his level of experience warrants a hearing regardless of whether you might agree or disagree with the sentiments so expressed.
SOPs don't have the answer and the commander is called upon to step up to the mark and earn his/her paypacket for the year in the next few seconds.
I'm a little uncomfortable with that as a broad statement. For the accel-stop manoeuvre (and that is the principal concern with V1) there is very little fudge factor (wiggle room, if you prefer) for accel-stop. This is especially so for the earlier aircraft .. indeed FAR 25 A/L 42, which introduced the requirement for a 2-second delay, recognised just this concern.
The relationship between V1 and accel-stop is an utter fudge anyway. When I was operating the 146 above the arctic circle, we went into plenty of runways that technically should have complied with all the requirements, but which you absolutely knew were too slimy for the crew to have much chance if they had to abort, particularly as the 146 is completely dependent on wheel brakes. V1 on those runways should have been about 50 kts. Another good example is the last third of 15 at Birmingham in the UK, technically the same as the rest of the runway but known to be bumpy and slippery in wet conditions.
However, it is very important to keep in mind that any takeoff at low weight, with min speed schedules, can bite the pilot hard ... either due to a Vmcg OR Vmca departure ... if he/she is a bit hamfisted. Indeed, if the pilot has not been trained for such takeoffs, then the gyrations can be very surprising ...
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Posted purely to add to the discussion, recognising that the amendments in force at the time of certification may have an influence. Bolding mine.
AC 25-7A
(3) Accelerate-Stop Time Delays. Section 25.101(h) of the FAR requires allowance for time delays in the execution of procedures. Amendment 25-42 (effective March 1, 1978) amended the airworthiness standards to clarify and standardize the method of applying these time delays to the accelerate-stop transition period. Amendment 25-42 also added the critical engine failure speed, VEF, and clarified the meaning of V1 with relation to VEF. The preamble to Amendment 25-42 states that “V1 is determined by adding to VEF (the speed at which the critical engine is assumed to fail) the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed and the instant at which the test pilot recognizes and reacts to the engine failure, as indicated by the pilot’s application of the first retarding means during accelerate-stop tests.” Thus it can be seen that V1 is not only intended to be at the end of the decision process, but it also includes the time it takes for the pilot to perform the first action to stop the airplane. The purpose of the time delays is to allow sufficient time (and distance) for a pilot, in actual operations, to accomplish the procedures for stopping the airplane. The time delays are not intended to allow extra time for making a decision to stop as the airplane passes through V1. Since the typical transport category airplane requires three pilot actions (i.e., brakes-throttles-spoilers) to achieve the final braking configuration, Amendment 25-42 defined a two-second time period, in § 25.109, to account for delays in activating the second and third deceleration devices. Amendment 25-92 (effective March 20, 1998) redefined, and reinterpreted the application of that two-second delay time as a distance increment equivalent to two seconds at V1. No credit may be taken for system transient effects (e.g., engine spin-down, brake pressure ramp-up, etc.) in determining this distance. The following paragraphs provide guidance related to the interpretation and application of delay times to show compliance with the accelerate-stop requirements of Amendment 25-92.
AC 25-7A
(3) Accelerate-Stop Time Delays. Section 25.101(h) of the FAR requires allowance for time delays in the execution of procedures. Amendment 25-42 (effective March 1, 1978) amended the airworthiness standards to clarify and standardize the method of applying these time delays to the accelerate-stop transition period. Amendment 25-42 also added the critical engine failure speed, VEF, and clarified the meaning of V1 with relation to VEF. The preamble to Amendment 25-42 states that “V1 is determined by adding to VEF (the speed at which the critical engine is assumed to fail) the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed and the instant at which the test pilot recognizes and reacts to the engine failure, as indicated by the pilot’s application of the first retarding means during accelerate-stop tests.” Thus it can be seen that V1 is not only intended to be at the end of the decision process, but it also includes the time it takes for the pilot to perform the first action to stop the airplane. The purpose of the time delays is to allow sufficient time (and distance) for a pilot, in actual operations, to accomplish the procedures for stopping the airplane. The time delays are not intended to allow extra time for making a decision to stop as the airplane passes through V1. Since the typical transport category airplane requires three pilot actions (i.e., brakes-throttles-spoilers) to achieve the final braking configuration, Amendment 25-42 defined a two-second time period, in § 25.109, to account for delays in activating the second and third deceleration devices. Amendment 25-92 (effective March 20, 1998) redefined, and reinterpreted the application of that two-second delay time as a distance increment equivalent to two seconds at V1. No credit may be taken for system transient effects (e.g., engine spin-down, brake pressure ramp-up, etc.) in determining this distance. The following paragraphs provide guidance related to the interpretation and application of delay times to show compliance with the accelerate-stop requirements of Amendment 25-92.
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Darwin Training Crash sparks Debate on Training
Pilot deaths spark risk debate - ABC News (Australian Broadcasting Corporation)
interesting topic on Darwin fatal crash.
interesting topic on Darwin fatal crash.
To wit - V 1 means the maximum speed in the takeoff at which the pilot must take the first action
Please read again, very carefully, what FAA actually says. Any of you flying Seattle tin, see the Boeing training material. The MD words might have been different --- but the intent is the same ----- because it all stems from the certification practices of FAR 25, as amended, and the related flight test guides.
An accurate definition of FAR 25 V1 is:
The speed at which the takeoff must be continued, if the abort has not already been commenced.
V1 is NOT the latest speed for a stop decision, V1 is a GO speed, the difference is significant and critical. The failure must be recognized, the decision made before V1.
We have come a long way in certification, from the days of SFAR 422B.
Tootle pip!!
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always the same type of accident, go below VMC, kick wrong rudder, and bye bye!!! or keep pulling yoke , stall, encounter turbulence, and go spin,...or kick wrong rudder, keep nose up, flat stall. etc.
what international law says?: "no engine shut down below 5000ft , 5000ft is the minimum altitude you must recover"
who's next?
what international law says?: "no engine shut down below 5000ft , 5000ft is the minimum altitude you must recover"
who's next?
Moderator
Couple of thoughts -
(a) There aren't many turboprops that don't have the power to either climb away well, or speed up when very light
Same applies to the jet brigade as well. However, the problem is not acceleration capability but risk of yaw departure. This is mainly a worry for min speed schedule takeoffs at low weights for aircraft which are Vmcg/Vmca limited. Hiccup once and you are in a world of hurt.
(b) The speed at which the takeoff must be continued, if the abort has not already been commenced.
This has been the mantra for the past 25-30 years. To paraphrase .. if you're not already stopping by V1, then you're going .. (caveat is those oddball loss of control situations when one might be forced to abort above V1)
As Brian notes above, it is important to keep in mind that V1 has varied in definition over the years and the relevant words in your particular AFM are the best guidance as to what is expected for the performance data to be reasonably predictable.
(a) There aren't many turboprops that don't have the power to either climb away well, or speed up when very light
Same applies to the jet brigade as well. However, the problem is not acceleration capability but risk of yaw departure. This is mainly a worry for min speed schedule takeoffs at low weights for aircraft which are Vmcg/Vmca limited. Hiccup once and you are in a world of hurt.
(b) The speed at which the takeoff must be continued, if the abort has not already been commenced.
This has been the mantra for the past 25-30 years. To paraphrase .. if you're not already stopping by V1, then you're going .. (caveat is those oddball loss of control situations when one might be forced to abort above V1)
As Brian notes above, it is important to keep in mind that V1 has varied in definition over the years and the relevant words in your particular AFM are the best guidance as to what is expected for the performance data to be reasonably predictable.
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However, the problem is not acceleration capability but risk of yaw departure.
This is mainly a worry for min speed schedule takeoffs at low weights for aircraft which are Vmcg/Vmca limited. Hiccup once and you are in a world of hurt.
So I guess my point is, there is no need to ever go to the place you are describing. It's a theoretical exercise that only needs to be carried out in the sim.
V1 is NOT the latest speed for a stop decision, V1 is a GO speed, the difference is significant and critical.
So what is your point, other than semantics?
For what it is worth, I always expect to stop until I hear V1, at which point I am absolutely going unless I cannot control the aircraft, or we have an uncontained fire.
Interesting development in the media...
Pilot deaths spark risk debate - ABC News (Australian Broadcasting Corporation)