737-200 V1 cut
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Originally Posted by Junkflyer
The FAA defines V-1 as the speed the maximum speed at which the takeoff maneuver can be initiated and the airplane stopped within the remaining field length under the conditions and procedures defined in the FAR's. Also the "go procedures, but this does not apply this particular discussion.
It has changed from a decision speed to an action speed. My airline teaches the V-1 call at V-1 minus 3 knots in order to initiate an abort by V-1.You can go to Faa.gov and search "takeoff safety" or go/no go decision. Way too much to post here, but full of good info.
It has changed from a decision speed to an action speed. My airline teaches the V-1 call at V-1 minus 3 knots in order to initiate an abort by V-1.You can go to Faa.gov and search "takeoff safety" or go/no go decision. Way too much to post here, but full of good info.
Generally, the way this is described is that V1 may not be less than VEF (this is the “critical engine speed”) plus the speed gained with that critical engine not operating during the interval of time between the engine failure and the pilot recognizing the engine failure (marked by when he/she takes the first action to either continue or to reject the takeoff). Obviously, it is important to know, and to know how to deal with, this particular term (i.e., V1)
However, this doesn’t necessarily become a critical issue until we start discussing the balanced field concept. In other words, if you were on one of the dry lake beds in the western US, you could theoretically take a nap between an engine failure and doing something about it – and it wouldn’t matter – safety wise. But on a runway with finite dimensions, you want to be able to get stopped, if you choose to stop, before you run out of runway … or you want to be able to get airborne, and be able to achieve the minimum altitude at the appropriate point (i.e., the takeoff distance ... and there is a specific definition for this term as well that I would recommend anyone really interested in this discussion take a moment to read) if you choose to go fly.
It’s not so much that I feel a need to argue about 2, 3, or 5 knots with respect to what V1 actually is and when it is “called,” because of where most airline operations take place today … that is, most (and I emphasize, MOST) of the airports where airline operations regularly occur, there has been some reasonable care taken to provide an excess of runway for most situations. But you and I don’t necessarily have all that information available to us … and to ignorantly change a procedure or alter a standard, is, in my not-so-humble opinion, balancing on the edge of the “stupid-cliff” – and just may result in falling into that chasm of “stupidity.” But, as I keep mentioning, I think what “irks” me most is when individuals begin to take liberties with what the rules say and either re-interpret them or completely disregard them. I’ve always operated under the concept that someone, someplace, set up the definitions and procedures for a reason. IF that reason no longer exists … fine … describe what is different … change the definition or the procedure … and explain why the new definition or procedure makes sense. IF someone just doesn’t like to have to comply with a definition or a procedure – which does happen – although most of the time this occurs it’s when someone hasn’t seen the conditions for which the definition or procedure was created for some time, they may feel that complying with any restriction is no longer valid. If it IS true that the definition or the procedure mandated is no longer valid … again, fine … explain what has changed and change or eliminate the definition or procedure. But regardless of the issue … I object to simply ignoring or changing what was established – regardless of the intention involved.
Originally Posted by glendalegoon
HE had some choice words for you, which I shall not post here out of respect for forum rules.
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air rabbit
I've now found data indicating the five knots before rule was first mentioned almost 20 years ago.
The reality of flying is sometimes different than the engineering of flying.
PEOPLE are involved with flying and that makes it a bit of an art as well as some science.
My training guy did review what you said. Perhaps you should review all that stuff junkflyer mentioned. After all if you wait until V1 is indicated on the ASI then you are finishing the words V1 after V1 has been exceeded.
YOU mentioned something about runways with margins. I can think of too many with less than generous margins here in the USA. And I think the reality of those airports lead to our way of doing things.
I do imagine a peer review journal might enjoy your writings.
I've now found data indicating the five knots before rule was first mentioned almost 20 years ago.
The reality of flying is sometimes different than the engineering of flying.
PEOPLE are involved with flying and that makes it a bit of an art as well as some science.
My training guy did review what you said. Perhaps you should review all that stuff junkflyer mentioned. After all if you wait until V1 is indicated on the ASI then you are finishing the words V1 after V1 has been exceeded.
YOU mentioned something about runways with margins. I can think of too many with less than generous margins here in the USA. And I think the reality of those airports lead to our way of doing things.
I do imagine a peer review journal might enjoy your writings.
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Originally Posted by glendalegoon
I've now found data indicating the five knots before rule was first mentioned almost 20 years ago.
The reality of flying is sometimes different than the engineering of flying.
PEOPLE are involved with flying and that makes it a bit of an art as well as some science.
My training guy did review what you said. Perhaps you should review all that stuff junkflyer mentioned. After all if you wait until V1 is indicated on the ASI then you are finishing the words V1 after V1 has been exceeded.
YOU mentioned something about runways with margins. I can think of too many with less than generous margins here in the USA. And I think the reality of those airports lead to our way of doing things.
I do imagine a peer review journal might enjoy your writings.
The reality of flying is sometimes different than the engineering of flying.
PEOPLE are involved with flying and that makes it a bit of an art as well as some science.
My training guy did review what you said. Perhaps you should review all that stuff junkflyer mentioned. After all if you wait until V1 is indicated on the ASI then you are finishing the words V1 after V1 has been exceeded.
YOU mentioned something about runways with margins. I can think of too many with less than generous margins here in the USA. And I think the reality of those airports lead to our way of doing things.
I do imagine a peer review journal might enjoy your writings.
Calling out “V-One” at a point 5 knots prior to the actual “V1” would not present a performance problem IF the decision to either reject or continue is always made in the favor of rejecting the takeoff. Why do I say that? If the engine were to fail at precisely the same moment as the “5 knots early” call of “V-ONE,” and the pilot flying immediately decided to reject by taking the necessary steps … simultaneously closing the throttles, exerting maximum pedal pressure on the brakes, and as soon as the throttles are snapped to the idle position, immediately grabbing and extending the ground spoilers, all while maintaining directional control through the rudder pedal steering, if necessary, backed up with a hand on the nose wheel steering controls … there is little doubt that the airplane could be brought to a stop within the confines of the runway. In fact, it probably would come to a stop at a point somewhat short of the distance shown by the “trace-around-charts” – which we rarely see anymore.
However, if the pilot flying were to decide differently … that is, decide to continue the takeoff … the airplane would have to continue accelerating without the thrust that would have been provided by that now-failed engine. Believe it or not, that is a LOT of lost thrust. That means that with less thrust to accelerate to the same rotation/takeoff speed, the takeoff roll would be some distance longer than originally planned, meaning that the airplane would become airborne somewhat later in the takeoff sequence … meaning that the now-reduced takeoff flight path would be moved further into the obstruction clearance pathway … which means that what had been a relatively obstruction-clear pathway may not (notice I did not say “will not” … I said “MAY not”) exist. Is that something to be concerned about? Probably not – at least not under a good share of the circumstances … but if this function can be cavalierly dismissed … what other “hard-n-fast” rules and regulations may also enjoy some level of relaxation?
Yes, we do have a procedure that the pilot monitoring will call out the appropriate numbers … well and good. But the vintage of pilots from which I come, would be hard pressed to NOT know themselves – without any input from anyone else in the cockpit – whether the airplane was accelerating normally or not – through both physical sense and knowledgeable reference to the airspeed indicator … and know when he/she had reached that magic number, V-One, without having to be told. In today’s vintage, if the guy/gal in the other seat didn’t call out “V-One,” I’m not at all sure that the pilot actually flying the airplane would have any idea about when the airplane had accelerated to that point.
The designation of “V-One” was developed to avoid a circumstance where an engine failure occurring at the most critical point on the takeoff roll and presenting an exceptionally difficult conundrum for the pilot (do I stop or do I go). A specific number was decided to be used – not the number, but what it represents – that being the division point that gives the pilot the best opportunity to make the correct decision … continue or stop. However, now we’re discussing the movement of that decision point – and this decision is based on … what? As I said it would provide for a better outcome if the decision was to “stop,” but I’m not at all sure that it would provide for a better outcome if the decision is to “go.”
As you’ve said – there may be far too many airports out there with "less than generous margins" - which, in my mind, should generate more, not less, concern about such a decision ... and should encourage additional discussion on this ... not abject silence. I believe that it should be considered a bit more seriously ... but, again, what could I possibly know? Well, I tried, but ... as you've said ... it’s not my airplane ... it’s not my airline ... but it also won’t be me on the witness stand.
My hope is that you have a very successful and safe career … and I’ll leave you with recalling a very famous line in a very old TV series … “choose wisely grasshopper.”
Last edited by AirRabbit; 11th Jan 2014 at 22:19.
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air rabbit
please review post 33. the v1 call is begun at five knots prior so as to complete the call by v1.
our airline has been doing fine since we started this procedure.
I encourage you to write for a peer reviewed journal. Perhaps the FAA will follow your lead. But right now, boeing, and the major airlines are doing it pretty much like I have written. AND THEY DO IT WITH FAA approval.
I've looked at the concept three ways till sunday and am in favor of it.
please review post 33. the v1 call is begun at five knots prior so as to complete the call by v1.
our airline has been doing fine since we started this procedure.
I encourage you to write for a peer reviewed journal. Perhaps the FAA will follow your lead. But right now, boeing, and the major airlines are doing it pretty much like I have written. AND THEY DO IT WITH FAA approval.
I've looked at the concept three ways till sunday and am in favor of it.
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glendalegoon:
I don’t normally continue an “on-line” discussion such as this with someone who has convinced me that he (or she) isn’t going to agree with my point of view … no matter what … but frankly you have impressed me with your tenacity and your determination (demonstrated by calling your training resource – which I think I said I admired) have got me to a point where I think it appropriate to offer one last “tid-bit” of information.
Some time ago, a group of aviation professionals were assembled into a multi-participant group, sanction by and participated in by the FAA, and quite a few airlines, airline organizations, pilots and pilot organizations, training organizations, and Airbus Industries, Boeing, and McDonnell Douglas … the later three of whom contributed performance data relating to rejected takeoffs. While the topic was Takeoff Training Safety – the primary thrust was clearly aimed at eliminating, or at least reducing the numbers of takeoff accidents occurring due to the improper actions of pilots – the vast majority of such accidents/incidents were due to rejecting the takeoff for various reasons, at various points along the takeoff runway. In case anyone is interested … for a fee, this document, called The Takeoff Safety Training Aid, a 298 page document, that goes into about as much detail as anyone could ever want (not much of an exaggeration … if any!) about takeoff issues, may be obtained by the general public from the National Technical Information Service (NTIS), 5285 Part Royal Road, Springfield, Virginia 22161, and for those of us with slightly shallower pockets, a Portable Document File (PDF) version of this document may be obtained from various sources on the internet.
This particular document was devoted to eliminating or at least reducing the number of takeoff related accidents and incidents. As such, there are sections that deal with things like “takeoff call-outs.” As such, this document describes the necessity of the pilot flying the airplane to include airspeed in his instrument scan during the takeoff ground roll, citing the fact that “…the pilot flying cannot react properly to V1 unless the V1 call is made in a timely, crisp, and audible manner.” In fact, this document references a US airline who had suggested “completing the V1 callout by the time the airplane reaches V1 – which, I take, was likely your airline. This reference is described as a means for helping to ensure that “…a decision to reject the takeoff is not made after V1 – which could be disastrous on some runways.” However, this document goes on to say that others have recommended calling out “Approaching” as the V1 speed is approached and then calling out “V1” as the airspeed reached the actual V1 speed. If a direct and simple “V1” call-out at the proper speed is, somehow, thought to be insufficient – for whatever reason – (even though its seemed to have worked well for a number of years) then I’d recommend this alternative!
Again – as I think I’ve indicated – IF (and please don’t disregard the contingency reference) if the focus is on initiating an RTO and completing it successfully –certainly calling out “V1” at a point prior to the actual V1 speed would certainly provide adequate runway in which the RTO could be completed successfully. BUT – as I’ve attempted to point out, if this is the intent, and something does occur in that region between the “approaching” call-out and the actual “V1” call-out and pilot flying confuses something said by the non-flying pilot with that pilot having called out “V1,” and the result is a decision to continue the takeoff – the circumstances certainly COULD lead to a dramatically unwanted result. Call me negatively fatalistic if you desire but given the opportunity for something to go wrong – what do you think the odds are that someone will do precisely what was NOT intended? And in the realm of airplane and airline operations, that is something I would go to great lengths to avoid.
OK … my friend … fly safe.
I don’t normally continue an “on-line” discussion such as this with someone who has convinced me that he (or she) isn’t going to agree with my point of view … no matter what … but frankly you have impressed me with your tenacity and your determination (demonstrated by calling your training resource – which I think I said I admired) have got me to a point where I think it appropriate to offer one last “tid-bit” of information.
Some time ago, a group of aviation professionals were assembled into a multi-participant group, sanction by and participated in by the FAA, and quite a few airlines, airline organizations, pilots and pilot organizations, training organizations, and Airbus Industries, Boeing, and McDonnell Douglas … the later three of whom contributed performance data relating to rejected takeoffs. While the topic was Takeoff Training Safety – the primary thrust was clearly aimed at eliminating, or at least reducing the numbers of takeoff accidents occurring due to the improper actions of pilots – the vast majority of such accidents/incidents were due to rejecting the takeoff for various reasons, at various points along the takeoff runway. In case anyone is interested … for a fee, this document, called The Takeoff Safety Training Aid, a 298 page document, that goes into about as much detail as anyone could ever want (not much of an exaggeration … if any!) about takeoff issues, may be obtained by the general public from the National Technical Information Service (NTIS), 5285 Part Royal Road, Springfield, Virginia 22161, and for those of us with slightly shallower pockets, a Portable Document File (PDF) version of this document may be obtained from various sources on the internet.
This particular document was devoted to eliminating or at least reducing the number of takeoff related accidents and incidents. As such, there are sections that deal with things like “takeoff call-outs.” As such, this document describes the necessity of the pilot flying the airplane to include airspeed in his instrument scan during the takeoff ground roll, citing the fact that “…the pilot flying cannot react properly to V1 unless the V1 call is made in a timely, crisp, and audible manner.” In fact, this document references a US airline who had suggested “completing the V1 callout by the time the airplane reaches V1 – which, I take, was likely your airline. This reference is described as a means for helping to ensure that “…a decision to reject the takeoff is not made after V1 – which could be disastrous on some runways.” However, this document goes on to say that others have recommended calling out “Approaching” as the V1 speed is approached and then calling out “V1” as the airspeed reached the actual V1 speed. If a direct and simple “V1” call-out at the proper speed is, somehow, thought to be insufficient – for whatever reason – (even though its seemed to have worked well for a number of years) then I’d recommend this alternative!
Again – as I think I’ve indicated – IF (and please don’t disregard the contingency reference) if the focus is on initiating an RTO and completing it successfully –certainly calling out “V1” at a point prior to the actual V1 speed would certainly provide adequate runway in which the RTO could be completed successfully. BUT – as I’ve attempted to point out, if this is the intent, and something does occur in that region between the “approaching” call-out and the actual “V1” call-out and pilot flying confuses something said by the non-flying pilot with that pilot having called out “V1,” and the result is a decision to continue the takeoff – the circumstances certainly COULD lead to a dramatically unwanted result. Call me negatively fatalistic if you desire but given the opportunity for something to go wrong – what do you think the odds are that someone will do precisely what was NOT intended? And in the realm of airplane and airline operations, that is something I would go to great lengths to avoid.
OK … my friend … fly safe.
Last edited by AirRabbit; 12th Jan 2014 at 03:03.
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LETs say you decide to continue a takeoff three knots prior to V1...what could happen. Your screen height might be 30 feet instead of 35 feet. It might be 20 feet instead of 35 feet.
LETS say you decide to abort the takeoff 3 knots after v1, you might end up in the harbor.
LETS say you decide to abort the takeoff 3 knots after v1, you might end up in the harbor.
Sorry Air Rabbit, but I have to agree with GlendaL here.
32 years in a euro flag carrier. We adopted that -5 callout decades ago, while still an all Boeing operator. We were told it was for the same reason Glenda just described - they preferred us to be GO oriented, especially on those short runways. The industry statistics seem to back up the philosophy too. Many more accidents seem to occur as a result of rejected take-offs than with taking the problem into the air and sorting it out.
Technically I can see exactly what you're saying, and it's all technically correct.
Operationally, things aren't always so clean and 'textbook'.
By the way - we went Airbus, and they have made it all moot now by having an auto callout at V1.
32 years in a euro flag carrier. We adopted that -5 callout decades ago, while still an all Boeing operator. We were told it was for the same reason Glenda just described - they preferred us to be GO oriented, especially on those short runways. The industry statistics seem to back up the philosophy too. Many more accidents seem to occur as a result of rejected take-offs than with taking the problem into the air and sorting it out.
Technically I can see exactly what you're saying, and it's all technically correct.
Operationally, things aren't always so clean and 'textbook'.
By the way - we went Airbus, and they have made it all moot now by having an auto callout at V1.
The OP at his post #16 mentions that his simulator tormentor is 'failing' an engine at V1 minus 5 to 10 knots, but he is attempting to continue the take-off and losing control. As he appears to only have about 250 hours experience, it is not surprising that the combination of a cranky old simulator, instantaneous total loss of thrust on one side with probable rated thrust on the other, and poor visuals are conspiring against him.
With such low-time students I would be cutting them some slack by introducing any failures sufficiently below V1 to make it clear to reject the take-off. About minus 10 to 15 knots at the latest. Otherwise I would be waiting to hear the "V one" call from the support pilot before pushing the big square 'fail' button on the console. If that call was unreasonably early, or late, it would be time to freeze the box and have them agree to call it at exactly the number bugged. Surely the object at this early stage of training is to set clear parameters and not to confuse by flying around in some twilight zone?
Whether a company's SOP wants it 2, 3 or 5 knots early is for the line training people when he gets the job. If he already has the job, that should have been sorted out prior to commencing simulator.
PS: 3 knots is about the thickness of the white bug on the old ASIs fitted to most Jurassics, and those ASIs aren't all that clinically accurate anyway. In the real aircraft (not sim!) it's not unusual for there to be a 3 knot split between sides. So on a limiting runway it really depends on how you read your ASI.....Calling V1 a smidge early can't hurt, SOP or no SOP. By a 'smidge' I mean about 3 knots, which lacking any suggestion of calling early in the standard Boeing SOP, is within a reasonable range of reading error and will certainly ensure that the call has been completed by actual V1.
With such low-time students I would be cutting them some slack by introducing any failures sufficiently below V1 to make it clear to reject the take-off. About minus 10 to 15 knots at the latest. Otherwise I would be waiting to hear the "V one" call from the support pilot before pushing the big square 'fail' button on the console. If that call was unreasonably early, or late, it would be time to freeze the box and have them agree to call it at exactly the number bugged. Surely the object at this early stage of training is to set clear parameters and not to confuse by flying around in some twilight zone?
Whether a company's SOP wants it 2, 3 or 5 knots early is for the line training people when he gets the job. If he already has the job, that should have been sorted out prior to commencing simulator.
PS: 3 knots is about the thickness of the white bug on the old ASIs fitted to most Jurassics, and those ASIs aren't all that clinically accurate anyway. In the real aircraft (not sim!) it's not unusual for there to be a 3 knot split between sides. So on a limiting runway it really depends on how you read your ASI.....Calling V1 a smidge early can't hurt, SOP or no SOP. By a 'smidge' I mean about 3 knots, which lacking any suggestion of calling early in the standard Boeing SOP, is within a reasonable range of reading error and will certainly ensure that the call has been completed by actual V1.
Last edited by Mach E Avelli; 12th Jan 2014 at 06:24.
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We were about to take off at San Jose Costa Rica one day in a B727 and it was an upslope runway heading into terrain so an early right turn was required. It is over 3,000 ft elevation and was a warm day.
I mentioned to the FO we were close to balanced field length because of our weight. He said that is ok because the other captain I have been flying with just sets V1 10 knots low. I said but that is illegal. He said, no it really works. I asked him if they ever aborted. He said no. I said what if you call V1 10 knots slow and I continue the take off, will I meet our climb requirements? No answer.
Why not just stay legal, it makes the hearing go so much better.
I mentioned to the FO we were close to balanced field length because of our weight. He said that is ok because the other captain I have been flying with just sets V1 10 knots low. I said but that is illegal. He said, no it really works. I asked him if they ever aborted. He said no. I said what if you call V1 10 knots slow and I continue the take off, will I meet our climb requirements? No answer.
Why not just stay legal, it makes the hearing go so much better.
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Well, to me, at least, it appears that some here are confusing calling “V1” at the correctly determined V1 speed with calling “V1” at something less than the correctly determined V1 speed – where the specific amount less than V1 to be individually determined by um … each airline? each fleet Captain? each Captain? each pilot? each what? And, the reason given for deciding on which of the above options is the appropriate choice is that the airline is “Go oriented” …really? I think that the post by bubbers44, above, (thanks bubbers) might bring at least some doubt into that conclusion.
This MAY come as a surprise to some here, but “calling out” anything during the takeoff roll is, in itself, totally meaningless. The issue here is to “call out” something meaningful at a very specifically identified airspeed … but not just any airspeed … an airspeed that is very specifically identified with the performance of that airplane, on that date, at that time, at the existing environmental conditions, at that gross weight, on that runway (with all of what that implies – gradient up or down – obstacles off the departure end – etc., etc.) all with a very specific thought in mind – whether or not to reject or continue the takeoff. Of course there are several events that might lead a flight crew to decide that it is not prudent to leap into the air – but that is entirely related to what event occurs and when that event occurs. Not all events are equally impacting on airplane performance and each event is not necessarily noticed as quickly as the other events. Obviously, the event that is the most notable is very likely an engine failure (at least that is the conclusion reached by the group that developed the Takeoff Training Safety Aid, described in my most recent post) – it is also likely the most performance affecting. The other events may or may not eventually lead to an engine failure, but if they were to occur when a rejected takeoff could be safely accomplished on the runway remaining, a rejected takeoff is probably the more appropriate course of action to take.
Of course, if an engine failure event were to occur within the same boundaries, i.e., enough runway remains in front of the airplane such that a rejected takeoff could be accomplished safely, logically, that would remain the more appropriate action to take. This is precisely why most airlines today have a pre-takeoff briefing that includes a review of what events would be cause for rejecting the takeoff. However, I think it appropriate to point out the fact that as we’re discussing whether or not to continue a takeoff alone implies the potential necessity to perform a rejected takeoff. In that we’ve pretty much decided on the “what” part of the concern, the next issue for consideration is, “where” would it be most appropriate to make such a decision? Obviously, that is directly dependent on the location of the airplane on the runway when this decision is made … is there enough runway left to stop … is there enough runway left to continue the takeoff?
There are some here who state “…Calling V1 a smidge early can't hurt, SOP or no SOP. By a 'smidge' I mean about 3 knots, which lacking any suggestion of calling early in the standard Boeing SOP, is within a reasonable range of reading error and will certainly ensure that the call has been completed by actual V1.” (Mach E Avelli) It is my impression that this statement is likely based on what we all recognize as the almost impossible task of calling out the precise time, to the second, if you plan to clearly say “3:15:45” when the second hand clicks to the “45” position; this is because by the time it takes to say each of those words, it’s likely already “46.” Granted. But IF there was an understanding that the time of “3:15:45” would be “called” by having the time-watcher saying, out loud, the word “NOW,” there is nothing that would preclude that time-watcher to say “NOW” just as the second hand clicked to the “45” position. Of course, if an airline wanted the airspeed “watcher” to be precise in calling out when the A/S reached a very precise number (and I have problems with the idea that one of the pilots’ eyes would be “glued” to the A/S indicator, but…) and, what is to be said is “You are now at V1 speed” or even a more simple statement of the specific airspeed, such as “One-thirty-two,” the same kind of argument could be made. But, as the call-out is a succinct “V-One,” I cannot see how the “exact-time-impossibility” argument can be used – at least with what I would call any credibility. If there is a built-in error in the A/S indications (which is a topic for an entirely different discussion) isn’t having such a known error already enough of a compromise? And if there is any question, please go back and re-read bubbers44, comment above. Obviously, that F/O recognized that calling V1 early, with those existing conditions, indicating that a problem, like an engine failure, occurring after that call, where it would be thought to be “too late” to reject, pretty much demanding that takeoff proceed, while recognizing that continuing the takeoff under the conditions cited, now with an engine inoperative, very well could have led to a very objectionable and unsatisfactory result.
As I’ve said (and some would say too many times) on this forum … I am opposed to making adjustments to prescribed procedures because it looks to be an appropriate way to “make it work” and relieve someone from having to perform as they were expected to perform. I’ve called those “cheat sheet” methods to accomplish something. Is this another “cheat sheet” issue? Is this particular issue so close to the edge that it makes a significant difference … apparently not. As anyone would recognize – airplanes and their engines do not always operate in accordance with the book descriptions. But does that give us the logical recourse to do something that “seems to work,” “works in the sim,” or some other “almost logical” reason? How close to being flat wrong does something have to be before it is recognized as being wrong? It is apparent that there are those here who have “called” V1 at a point well prior to the actual V1 – and have done so without any problems … at least, so far. Does that make it right? I think each of us is going to have to make those kinds of decisions either on our own or with some responsible party's recommendation or edict. The regulations sound pretty clear to me. Are these regulations right? Should they be changed? There seems to have been a rather major effort to determine what, if anything should be done – reference the Takeoff Training Safety Aid document. So, what do we do now? I know what I’m going to do. It seems that our colleague bubbers44, had it pretty much nailed when he said “Why not just stay legal, it makes the hearing go so much better.”
This MAY come as a surprise to some here, but “calling out” anything during the takeoff roll is, in itself, totally meaningless. The issue here is to “call out” something meaningful at a very specifically identified airspeed … but not just any airspeed … an airspeed that is very specifically identified with the performance of that airplane, on that date, at that time, at the existing environmental conditions, at that gross weight, on that runway (with all of what that implies – gradient up or down – obstacles off the departure end – etc., etc.) all with a very specific thought in mind – whether or not to reject or continue the takeoff. Of course there are several events that might lead a flight crew to decide that it is not prudent to leap into the air – but that is entirely related to what event occurs and when that event occurs. Not all events are equally impacting on airplane performance and each event is not necessarily noticed as quickly as the other events. Obviously, the event that is the most notable is very likely an engine failure (at least that is the conclusion reached by the group that developed the Takeoff Training Safety Aid, described in my most recent post) – it is also likely the most performance affecting. The other events may or may not eventually lead to an engine failure, but if they were to occur when a rejected takeoff could be safely accomplished on the runway remaining, a rejected takeoff is probably the more appropriate course of action to take.
Of course, if an engine failure event were to occur within the same boundaries, i.e., enough runway remains in front of the airplane such that a rejected takeoff could be accomplished safely, logically, that would remain the more appropriate action to take. This is precisely why most airlines today have a pre-takeoff briefing that includes a review of what events would be cause for rejecting the takeoff. However, I think it appropriate to point out the fact that as we’re discussing whether or not to continue a takeoff alone implies the potential necessity to perform a rejected takeoff. In that we’ve pretty much decided on the “what” part of the concern, the next issue for consideration is, “where” would it be most appropriate to make such a decision? Obviously, that is directly dependent on the location of the airplane on the runway when this decision is made … is there enough runway left to stop … is there enough runway left to continue the takeoff?
There are some here who state “…Calling V1 a smidge early can't hurt, SOP or no SOP. By a 'smidge' I mean about 3 knots, which lacking any suggestion of calling early in the standard Boeing SOP, is within a reasonable range of reading error and will certainly ensure that the call has been completed by actual V1.” (Mach E Avelli) It is my impression that this statement is likely based on what we all recognize as the almost impossible task of calling out the precise time, to the second, if you plan to clearly say “3:15:45” when the second hand clicks to the “45” position; this is because by the time it takes to say each of those words, it’s likely already “46.” Granted. But IF there was an understanding that the time of “3:15:45” would be “called” by having the time-watcher saying, out loud, the word “NOW,” there is nothing that would preclude that time-watcher to say “NOW” just as the second hand clicked to the “45” position. Of course, if an airline wanted the airspeed “watcher” to be precise in calling out when the A/S reached a very precise number (and I have problems with the idea that one of the pilots’ eyes would be “glued” to the A/S indicator, but…) and, what is to be said is “You are now at V1 speed” or even a more simple statement of the specific airspeed, such as “One-thirty-two,” the same kind of argument could be made. But, as the call-out is a succinct “V-One,” I cannot see how the “exact-time-impossibility” argument can be used – at least with what I would call any credibility. If there is a built-in error in the A/S indications (which is a topic for an entirely different discussion) isn’t having such a known error already enough of a compromise? And if there is any question, please go back and re-read bubbers44, comment above. Obviously, that F/O recognized that calling V1 early, with those existing conditions, indicating that a problem, like an engine failure, occurring after that call, where it would be thought to be “too late” to reject, pretty much demanding that takeoff proceed, while recognizing that continuing the takeoff under the conditions cited, now with an engine inoperative, very well could have led to a very objectionable and unsatisfactory result.
As I’ve said (and some would say too many times) on this forum … I am opposed to making adjustments to prescribed procedures because it looks to be an appropriate way to “make it work” and relieve someone from having to perform as they were expected to perform. I’ve called those “cheat sheet” methods to accomplish something. Is this another “cheat sheet” issue? Is this particular issue so close to the edge that it makes a significant difference … apparently not. As anyone would recognize – airplanes and their engines do not always operate in accordance with the book descriptions. But does that give us the logical recourse to do something that “seems to work,” “works in the sim,” or some other “almost logical” reason? How close to being flat wrong does something have to be before it is recognized as being wrong? It is apparent that there are those here who have “called” V1 at a point well prior to the actual V1 – and have done so without any problems … at least, so far. Does that make it right? I think each of us is going to have to make those kinds of decisions either on our own or with some responsible party's recommendation or edict. The regulations sound pretty clear to me. Are these regulations right? Should they be changed? There seems to have been a rather major effort to determine what, if anything should be done – reference the Takeoff Training Safety Aid document. So, what do we do now? I know what I’m going to do. It seems that our colleague bubbers44, had it pretty much nailed when he said “Why not just stay legal, it makes the hearing go so much better.”
Last edited by AirRabbit; 12th Jan 2014 at 20:35.
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This is from the Faa.gov website. V-1 means initiate the reject (or not) at this point in time. A half second later you continue and fly the airplane on the remaining engine(s)
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Originally Posted by Junkflyer
V-1 means initiate the reject (or not) at this point in time. A half second later you continue and fly the airplane on the remaining engine(s).
Selecting a lower V1 speed, thereby moving that “decision point” further away from the departure end of the runway, must carry an acknowledgement that should an abort-worthy event occur prior to that newly-selected point, a rejected takeoff may certainly be accomplished successfully (just as it would had that point NOT been moved and had the same failure take place prior to reaching that speed). However, it must also be acknowledged, that should that same abort-worthy failure occur just after the newly selected point, after the adjusted V1 call out, the continued takeoff will continue over a longer portion of the runway with that failure than was originally anticipated. That sounds to me like “…measure-with-a-micrometer, mark-with-a-grease-pencil, and-cut-with-an-ax” approach to takeoff calculations. I was always under the impression that following the regulations was what all airlines had agreed, at least in principle, to do, and do on a regular basis. I do not believe that the regulations were written and debated, and eventually agreed, only to have some of them later treated as suggestions that may be disregarded as cavalierly as some here suggest is done regularly. My guess is that IF the concern with this specific designation that is apparently being voiced here was brought to the attention of the appropriate authorities there would be a somewhat detailed decision rendered – I would hope – and after a meaningful discussion and presentation of facts, opinions, objections, and other concerns had taken place, a single, understood, plainly written regulatory requirement would be put into place – and if, or where necessary, alternatives to that requirement and the conditions and limitations to those alternatives would be published alongside. Anything less holds the whole regulatory structure up for ridicule and mockery.
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Originally Posted by Junkflyer
Click the link and go to paragraph 2.3.1.2. It is an FAA publication defining V-1.
However, if you read the very next section in that same document, you will read the concerns I’ve been describing for not continuing the takeoff after passing what is called “V1.” If you understand the caveats in that next paragraph and you continue to desire to call “V1” at a reduced point … you should be able to see that there now is a confusion regarding how to recognize the point at which the takeoff would be assured even the experiencing a failure - even an engine failure - which has been identified as "V1." But if this definition has now been modified to allow a "reduced V1" the question remains, should we develop a requirement to generate a “second” call-out - where one would be for the “reduced V1” and the second one for the “real V1” - if so, certainly we would have do so without confusing the issue. The first “V1” would be for helping to ensure stopping distance (that is if you choose to stop before you hear “the first V1" (or whatever we determine to call it), you are safe to stop. The “2nd V1" call-out would be for helping to ensure that sufficient performance has been achieved to allow a safe takeoff, even if there were an engine failure AT or AFTER that point. BUT – NOW we have a problem in understanding what to do if an abort-worthy event occurs BETWEEN those two call-outs … go? Or stop? Here’s a suggestion … why not select an airspeed where any abort worthy event occurring prior to that airspeed will ensure sufficient runway to stop AND if that speed is reached prior to any abort-worthy event occurring, we can be assured that sufficient airplane performance has been achieved to allow a safe takeoff – even if the failure was an engine failure. Hmm… wait … don’t we already HAVE that?
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Yes, we do. It is called V1. Reinventing different V1 speeds because of pilot or company procedures only takes away from what V1 means. Below V1 you abort, above V1 you continue. The one second to react might occupy some pilots minds but after 23,000 hrs never felt it was worth factoring in. I guess the old KISS factor kept me out of making simple things complicated.
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Below V1 you abort, above V1 you continue.
Since decades gone past when I first read research papers on aircraft over-runs caused by a botched abort process, it was clear to me that the chances of an over-run from an engine failure near V1 was much higher in terms of danger than a go decision and take your chances on clipping trees in the initial climb out. There were plenty of over-run accidents in the files but I never saw a tree clipping event due lower screen height.
Since then I had in mind on every take off to keep going in event of engine failure or problem after 15 knots below V1. Tyre failures near V1 have proved to have been the cause of disastrous accidents where the crew aborted instead of continuing. Boeing have addressed these risks to some degree by using 80 knots as a decision speed to stop or go with certain failures. The risk of confusion and hence delayed action increases when the first officer does the take off and an event near V1 causes the captain to resume control and then abort.
15 knots was an arbitrary figure in my mind based upon what I had observed first hand during simulator training. Probably not legal and sure to arouse controversy but I could live with that. The secret was not to tell the first officer and cause potential conflicting views. In any case, few that I knew ever read old accident reports.
Since decades gone past when I first read research papers on aircraft over-runs caused by a botched abort process, it was clear to me that the chances of an over-run from an engine failure near V1 was much higher in terms of danger than a go decision and take your chances on clipping trees in the initial climb out. There were plenty of over-run accidents in the files but I never saw a tree clipping event due lower screen height.
Since then I had in mind on every take off to keep going in event of engine failure or problem after 15 knots below V1. Tyre failures near V1 have proved to have been the cause of disastrous accidents where the crew aborted instead of continuing. Boeing have addressed these risks to some degree by using 80 knots as a decision speed to stop or go with certain failures. The risk of confusion and hence delayed action increases when the first officer does the take off and an event near V1 causes the captain to resume control and then abort.
15 knots was an arbitrary figure in my mind based upon what I had observed first hand during simulator training. Probably not legal and sure to arouse controversy but I could live with that. The secret was not to tell the first officer and cause potential conflicting views. In any case, few that I knew ever read old accident reports.