737-200 V1 cut
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The Long and Short of the Discussion - in my view
As much as I hate to sound like a broken record … it surely sounds like there are more than just a few who fly airplanes and are VERY FORTUNATE folks to still be here. The point that I think keeps escaping most is that there was a specific reason for having developed the “V-speeds” that are contained in the US regulations – and similar requirements in other nations. I am fully aware of how the numbers work and what they mean – and that humans using those numbers are likely to make some, even if only minor, mistakes … but that doesn’t alter the fact that sometimes it’s only a matter of small, sometimes very small, differences that wind up being THE difference between life and death – or at least accident or no accident. That is the biggest reason I’ve been on my “rant” of examining a lot of the “short cut” procedures that I’ve seen cropping up in daily operations … I call them “cheat sheet” methods to assist in either getting through the training or through a check - that sometimes creep into line operations. MOST of the time, those “cheat sheet” issues are derived from what works in … and then is offered to others to apply to … simulator sessions. Unfortunately, IF those procedures are learned well (and they almost have to be to be used to get through training or checks), there is a good chance that they will find their way into line operations. Two things about that:
1. There is no one around who is a bigger supporter of the use of simulation than yours truly … with the caveat that I regularly offer … that being that I do expect that the simulator should be fully known by the person running the show in that simulator … i.e., either the instructor or the evaluator … and that is because a simulator is NOT an airplane – and the ONLY reason it looks and functions as much like the airplane as it does is because a lot of people have put a lot of effort into making it seem that way. As long as the use of the simulator is kept within the boundaries of what the limitations of the physicality of what that simulator can support … how the programmers have incorporated data generated from an in-flight airplane … how quickly (both independently and dependently) any input made to the simulated airplane (either from the simulated airplane’s controls, i.e., the flight controls, throttles, brakes, etc., or the Instructor’s Control Panel) can be computed, compared to the airplane data, a result generated, and provide an output in the form of a simulator aerodynamic response … the simulator will, indeed, accurately reflect just what the airplane would have done in those limited case applications. However, if you get just outside of those very limited parameters (and believe me, the boundaries of those parameters have been expanded by unbelievable amounts over the last 3 decades!!!) you get into a simulator response that could very easily not be anything like what the airplane would have done. In fact there is an on-going effort – as some of you are aware – titled the “International Committee for Aviation Training in Extended Envelopes” which was specifically chartered to examine what kinds of any additional data or additional data sources would be necessary or possible from which additional simulator programming data could be acquired and used to program simulators to more realistically simulate a given airplane make, model, series, outside of what had been considered the “normal” operating envelope of that particular simulator.
2. Instead of something being developed in a simulator for simulator training or checking purposes, there seems to be those who believe it appropriate, during line operations, to disregard the identified speed above which an abort-worthy event occurring must NOT result in the initiation of an RTO (a Rejected Take Off). Instead, these persons believe that the identified speed does not provide an adequate margin of safety to stop if the RTO is initiated precisely at that speed, and they have decided that they will “reduce” that speed to provide additional runway to enable a safe RTO, should it be required. Once this procedure is decided upon and word is passed between crew members, this procedure is eventually adopted in some simulator training sessions. To no one’s surprise, selection of such a speed that would provide adequate stopping capability in an airplane, also provides adequate stopping capability in the simulator. However, an observant instructor or evaluator can usually pick up on the adjusted “V1” call and question the practice. It doesn’t happen often … but it DOES happen. Then comes the confusion. Additionally, here, in an anonymous forum, there is more freedom to describe such an event without fear of any repercussions (other than verbal). But the fact remains – while such an arbitrary speed reduction does, in fact, provide a greater margin for a successful RTO if initiated at or prior to the “reduced V1 call-out,” in fact, it ALSO leaves an increasingly gaping hole for what might happen if such an abort-worthy failure occurs AFTER that same “reduced V1 call-out.” And that is even more true in the airplane than it could ever be in a simulator.
So … again … overall … I fully understand the motivation that exists for the kinds of things this thread has brought out … BUT … before anyone arbitrarily reduces the speed at which they will “call out” V-ONE, please consider the facts of what that decision may impose on you if another, equally possible failure were to occur – or that same failure were to occur at a slightly later time. The results could be a lot more disastrous … by any measure. If it is your company that has “mandated” your compliance with this “procedure,” I would strongly urge to to bring that question before some arbitration panel or group to discuss the merits and demerits of such a compromise in what the regulatory requirement was intended to provide. If the rule should be changed for one operator … it should be changed for all operators – regardless of what that change entails. If the rule should not be changed – it shouldn’t be allowed to be “adjusted” on an individual basis.
(and by the way -- thanks Bubbers44 - for your cogent input)
1. There is no one around who is a bigger supporter of the use of simulation than yours truly … with the caveat that I regularly offer … that being that I do expect that the simulator should be fully known by the person running the show in that simulator … i.e., either the instructor or the evaluator … and that is because a simulator is NOT an airplane – and the ONLY reason it looks and functions as much like the airplane as it does is because a lot of people have put a lot of effort into making it seem that way. As long as the use of the simulator is kept within the boundaries of what the limitations of the physicality of what that simulator can support … how the programmers have incorporated data generated from an in-flight airplane … how quickly (both independently and dependently) any input made to the simulated airplane (either from the simulated airplane’s controls, i.e., the flight controls, throttles, brakes, etc., or the Instructor’s Control Panel) can be computed, compared to the airplane data, a result generated, and provide an output in the form of a simulator aerodynamic response … the simulator will, indeed, accurately reflect just what the airplane would have done in those limited case applications. However, if you get just outside of those very limited parameters (and believe me, the boundaries of those parameters have been expanded by unbelievable amounts over the last 3 decades!!!) you get into a simulator response that could very easily not be anything like what the airplane would have done. In fact there is an on-going effort – as some of you are aware – titled the “International Committee for Aviation Training in Extended Envelopes” which was specifically chartered to examine what kinds of any additional data or additional data sources would be necessary or possible from which additional simulator programming data could be acquired and used to program simulators to more realistically simulate a given airplane make, model, series, outside of what had been considered the “normal” operating envelope of that particular simulator.
2. Instead of something being developed in a simulator for simulator training or checking purposes, there seems to be those who believe it appropriate, during line operations, to disregard the identified speed above which an abort-worthy event occurring must NOT result in the initiation of an RTO (a Rejected Take Off). Instead, these persons believe that the identified speed does not provide an adequate margin of safety to stop if the RTO is initiated precisely at that speed, and they have decided that they will “reduce” that speed to provide additional runway to enable a safe RTO, should it be required. Once this procedure is decided upon and word is passed between crew members, this procedure is eventually adopted in some simulator training sessions. To no one’s surprise, selection of such a speed that would provide adequate stopping capability in an airplane, also provides adequate stopping capability in the simulator. However, an observant instructor or evaluator can usually pick up on the adjusted “V1” call and question the practice. It doesn’t happen often … but it DOES happen. Then comes the confusion. Additionally, here, in an anonymous forum, there is more freedom to describe such an event without fear of any repercussions (other than verbal). But the fact remains – while such an arbitrary speed reduction does, in fact, provide a greater margin for a successful RTO if initiated at or prior to the “reduced V1 call-out,” in fact, it ALSO leaves an increasingly gaping hole for what might happen if such an abort-worthy failure occurs AFTER that same “reduced V1 call-out.” And that is even more true in the airplane than it could ever be in a simulator.
So … again … overall … I fully understand the motivation that exists for the kinds of things this thread has brought out … BUT … before anyone arbitrarily reduces the speed at which they will “call out” V-ONE, please consider the facts of what that decision may impose on you if another, equally possible failure were to occur – or that same failure were to occur at a slightly later time. The results could be a lot more disastrous … by any measure. If it is your company that has “mandated” your compliance with this “procedure,” I would strongly urge to to bring that question before some arbitration panel or group to discuss the merits and demerits of such a compromise in what the regulatory requirement was intended to provide. If the rule should be changed for one operator … it should be changed for all operators – regardless of what that change entails. If the rule should not be changed – it shouldn’t be allowed to be “adjusted” on an individual basis.
(and by the way -- thanks Bubbers44 - for your cogent input)
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As a sideline view ... one of the main problems relates to the fact that certification stuff is idealised, not real world. The ICAO/regulatory task, progressively, is to reduce the delta.
(a) if the real world circumstances reasonably match the certification, then the outcome in the real world should be reasonably similar to what the (certification) book (AFM) suggests if the action sequence is done per the book.
(b) if not, then expect a variable and, perhaps, significantly variable, delta between the real world results and the certification suggestions.
How do both operator and commander handle this ? No simple answer but a lot of use is made of historical statistics and accident reports to come up with reasonably conservative SOPs for a start.
Winging it on the day is a recipe for disaster sooner or later. Overall the sensible use of historical statistics makes for a more reliable and predictable outcome. That's not to suggest that it will work ALL the time .. but, certainly, it will work MOST of the time.
(a) if the real world circumstances reasonably match the certification, then the outcome in the real world should be reasonably similar to what the (certification) book (AFM) suggests if the action sequence is done per the book.
(b) if not, then expect a variable and, perhaps, significantly variable, delta between the real world results and the certification suggestions.
How do both operator and commander handle this ? No simple answer but a lot of use is made of historical statistics and accident reports to come up with reasonably conservative SOPs for a start.
Winging it on the day is a recipe for disaster sooner or later. Overall the sensible use of historical statistics makes for a more reliable and predictable outcome. That's not to suggest that it will work ALL the time .. but, certainly, it will work MOST of the time.
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Nicely Said JT!
JT … a very reasonable synopsis of what’s been posted … as usual.
The document that’s been referenced now several times, the Takeoff Training Safety Aid is a 300-page document that does essentially recap most of the original concerns, took into consideration a great deal of the takeoff accidents / incidents (both rejected and continued takeoff) and as we’ve pointed out, that group completely understands the desire to ensure adequate amount of runway remaining in case an RTO is chosen … but they acknowledge that should something else happen (I’ve used the term “abort-worthy failure”) immediately or within seconds of that now-reduced speed call-out, the decision will have become much more complicated to address. Because there was apparently very vocal groups wanting to push for one or another of the individualized approaches, the task of the folks running the effort AND the airplane manufacturers – who were on the “hot-spot” for making the data available and ensuring its accuracy – the result was the “kinda-sorta” two-point description of this “mysteriously defined” speed called “V1” … that says the following:
First, V1 is the maximum speed at which the rejected takeoff maneuver can be initiated and the airplane stopped within the remaining field length under the conditions and procedures defined in the FAR’s. It is the latest point in the takeoff roll where a stop can be initiated.
Second, VI is the earliest point from which an engine out takeoff can be continued and the airplane can attain a height of 35 feet at the end of the runway.
The way I’ve always described the V1 speed importance is to say that the pilot flying has to be ready to abort the takeoff if or when he/she deems it appropriate to do so. Once the power is advanced and stabilized and the brakes are released (normally these things are accomplished simultaneously) there are only two(2) actions that the pilot performing the takeoff can take:
1. reject the takeoff; or
2. continue the takeoff.
The pilot flying may, in his/her own consideration of any possible problem, reject the takeoff at any time UP UNTIL the other pilot says V1, at that point and forward the takeoff is to be continued. In other words, the so-called “decision” is being contemplated from brake release until hearing “V1” – at that point there is NO decision, if the pilot flying had not already initiated the RTO, he/she is now committed to continue the takeoff. That specific speed has been colloquially referred to as “the decision speed,” when it is probably more accurate to colloquially refer to this number as “the no decision speed,” since the decision will have already been made. We shouldn’t have to get wrapped around the axle in trying to determine what that speed actually means. It’s been defined. It’s been described. It’s that we have apparently done a poor job in making line pilots understand the correct meaning of the term.
Perhaps what we should have been saying is ... the pilot flying may decide to reject at any time up until he/she hears “V1” called out, from that point forward the pilot flying is committed to completing the takeoff. If the pilot flying initiates the abort procedure (moves the throttles aft; steps on the brakes; extends the spoilers, or any combination) before he/she hears the other pilot call out “V1” – the airplane should have sufficient runway to safely stop. IF the pilot flying slams the throttles shut and does so simultaneously with the other pilot calling out "V1," we would see the penultimate example of the absolute latest point at which the RTO can be initiated - and it WOULD have been initiated ... in that the throttles were closed - there are no "do-overs" - the airplane is stopping! Observing the penultimate example of the earliest point at which the takeoff is committed, by definition, is not likely to be able to be observed, because there is no observable action that the pilot flying would take to “continue” doing what he/she had been doing from the initiation of the takeoff roll ... the only "observable" action would be to observe the pilot flying taking "no action" as the "V1" callout is made.
The document that’s been referenced now several times, the Takeoff Training Safety Aid is a 300-page document that does essentially recap most of the original concerns, took into consideration a great deal of the takeoff accidents / incidents (both rejected and continued takeoff) and as we’ve pointed out, that group completely understands the desire to ensure adequate amount of runway remaining in case an RTO is chosen … but they acknowledge that should something else happen (I’ve used the term “abort-worthy failure”) immediately or within seconds of that now-reduced speed call-out, the decision will have become much more complicated to address. Because there was apparently very vocal groups wanting to push for one or another of the individualized approaches, the task of the folks running the effort AND the airplane manufacturers – who were on the “hot-spot” for making the data available and ensuring its accuracy – the result was the “kinda-sorta” two-point description of this “mysteriously defined” speed called “V1” … that says the following:
First, V1 is the maximum speed at which the rejected takeoff maneuver can be initiated and the airplane stopped within the remaining field length under the conditions and procedures defined in the FAR’s. It is the latest point in the takeoff roll where a stop can be initiated.
Second, VI is the earliest point from which an engine out takeoff can be continued and the airplane can attain a height of 35 feet at the end of the runway.
The way I’ve always described the V1 speed importance is to say that the pilot flying has to be ready to abort the takeoff if or when he/she deems it appropriate to do so. Once the power is advanced and stabilized and the brakes are released (normally these things are accomplished simultaneously) there are only two(2) actions that the pilot performing the takeoff can take:
1. reject the takeoff; or
2. continue the takeoff.
The pilot flying may, in his/her own consideration of any possible problem, reject the takeoff at any time UP UNTIL the other pilot says V1, at that point and forward the takeoff is to be continued. In other words, the so-called “decision” is being contemplated from brake release until hearing “V1” – at that point there is NO decision, if the pilot flying had not already initiated the RTO, he/she is now committed to continue the takeoff. That specific speed has been colloquially referred to as “the decision speed,” when it is probably more accurate to colloquially refer to this number as “the no decision speed,” since the decision will have already been made. We shouldn’t have to get wrapped around the axle in trying to determine what that speed actually means. It’s been defined. It’s been described. It’s that we have apparently done a poor job in making line pilots understand the correct meaning of the term.
Perhaps what we should have been saying is ... the pilot flying may decide to reject at any time up until he/she hears “V1” called out, from that point forward the pilot flying is committed to completing the takeoff. If the pilot flying initiates the abort procedure (moves the throttles aft; steps on the brakes; extends the spoilers, or any combination) before he/she hears the other pilot call out “V1” – the airplane should have sufficient runway to safely stop. IF the pilot flying slams the throttles shut and does so simultaneously with the other pilot calling out "V1," we would see the penultimate example of the absolute latest point at which the RTO can be initiated - and it WOULD have been initiated ... in that the throttles were closed - there are no "do-overs" - the airplane is stopping! Observing the penultimate example of the earliest point at which the takeoff is committed, by definition, is not likely to be able to be observed, because there is no observable action that the pilot flying would take to “continue” doing what he/she had been doing from the initiation of the takeoff roll ... the only "observable" action would be to observe the pilot flying taking "no action" as the "V1" callout is made.
Last edited by AirRabbit; 15th Jan 2014 at 22:07.
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THANKS PPRUNE FAMILY
Sorry this is coming late.
i appreciate all the information.
I got the v1 cut the second time i tried it
thanks to you guys on this really wonderful site
I aced the ride
i appreciate all the information.
I got the v1 cut the second time i tried it
thanks to you guys on this really wonderful site
I aced the ride
Moderator
Couple of thoughts, where we are looking at new chums transitioning to jets.
I always found it very useful, for such folk in the initial OEI work, to run a couple of failures on the longest sim runway I had available but get the pilot to stay on the runway and just rudder the aircraft down the centreline.
Providing the box fidelity was half sensible for rudder (prior to the FAA's push post the 737 hardover problems this wasn't necessarily the case for -200 sims) this provided a good idea of the relationship between speed and rudder input required to keep on the line after the initial divergence was brought under control.
The second exercise, as competence improved, was to spend some time progressively reducing to a Vmca/Vmcg limiting schedule and CG. The arms and legs exercise required resulted in no further problems with "normal" failure sequences ....
The better manipulators regularly ended up able to handle the worst the box could throw at them for a 0/0 takeoff with a requirement to backtrack the LLZ. The effect on confidence was dramatic.
I always found it very useful, for such folk in the initial OEI work, to run a couple of failures on the longest sim runway I had available but get the pilot to stay on the runway and just rudder the aircraft down the centreline.
Providing the box fidelity was half sensible for rudder (prior to the FAA's push post the 737 hardover problems this wasn't necessarily the case for -200 sims) this provided a good idea of the relationship between speed and rudder input required to keep on the line after the initial divergence was brought under control.
The second exercise, as competence improved, was to spend some time progressively reducing to a Vmca/Vmcg limiting schedule and CG. The arms and legs exercise required resulted in no further problems with "normal" failure sequences ....
The better manipulators regularly ended up able to handle the worst the box could throw at them for a 0/0 takeoff with a requirement to backtrack the LLZ. The effect on confidence was dramatic.
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It was mentioned that Airbus has an automated V1 callout.
Does that occur at V1 or at V1-x?
Does that occur at V1 or at V1-x?
An auto-callout announces when the speed reaches V1.
I don't know how the call-out is programmed, but 2 knots or thereabouts before V1 seems to be consistent.
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Hmmmm....
Quote from A380 FCOM
An auto-callout announces when the speed reaches V1.
An auto-callout announces when the speed reaches V1.
Without any doubt the auto-callout for V1 is announced slightly before V1 is reached.
Last edited by AirRabbit; 13th Feb 2014 at 03:41.
Automated V1 call on A380
Hi AirRabbit,
As no A380 pilot has answered your question, here's a suggestion. The automated call - "Vee wun" - is likely to be slow and precise. If it commenced at the precise figure of V1, the "wun" would not be heard until after V1, potentially leading to a late abort. It may be that the SOP is to treat the "wun" as defining the decision point.
Perhaps the above will provoke a properly informed response!
As no A380 pilot has answered your question, here's a suggestion. The automated call - "Vee wun" - is likely to be slow and precise. If it commenced at the precise figure of V1, the "wun" would not be heard until after V1, potentially leading to a late abort. It may be that the SOP is to treat the "wun" as defining the decision point.
Perhaps the above will provoke a properly informed response!
The V1 call in simulator training general, is normally made by the PM. From personal observation the vast majority are called slightly late and I have never observed an early call. By slightly late, I mean one second or more after the ASI has gone through V1 and I am not talking about the deliberate V1 minus 5 call under discussion.
It should be remembered calls by the PM for (say) 80 knots or 100 knots or V1 or VR, during the take off run are purely support calls or back-up calls. They are not supposed to be action calls. If for some reason the PM fails to make any one of these calls, it shouldn't matter to the decision making of the captain who has his own ASI.
The captain and first officer each have an ASI. Depending on the design, there may be moveable "bugs" set at V1 and VR as well as other speeds. Assuming the company procedure is the captain is handling pilot for all rejected take off procedures, then he should be well aware of V1 and that is by observing his own ASI. The PM support call is handy as a reminder and that is all.
Again from numerous observations in simulators during type rating training where the PM who makes the support calls is quietly told by the instructor, to "forget" to call VR, we have seen some alarmingly hesitant delays by the PF who then fails to rotate at the correct VR because he momentarily disbelieves his own ASI simply because of no call by the PM.
In other words he was waiting until being told by the PM to rotate The worst I saw was the PF staying on the runway 37 knots after the bugged VR because he was waiting for the PM to call "Rotate". As we went into the overrun and through the localiser aerials, the PF looked across the cockpit at the PM and said accusingly "You forgot to call `Rotate`"
A smart pilot will always have an eye on the ground speed reading nearing VR and knows what its approximate indication should be approaching the airspeed check at 80 knots (737) and especially nearing VR. The PM support calls during the take off roll will always be with us but as said earlier, they are back up only - not necessarily action calls.
It should be remembered calls by the PM for (say) 80 knots or 100 knots or V1 or VR, during the take off run are purely support calls or back-up calls. They are not supposed to be action calls. If for some reason the PM fails to make any one of these calls, it shouldn't matter to the decision making of the captain who has his own ASI.
The captain and first officer each have an ASI. Depending on the design, there may be moveable "bugs" set at V1 and VR as well as other speeds. Assuming the company procedure is the captain is handling pilot for all rejected take off procedures, then he should be well aware of V1 and that is by observing his own ASI. The PM support call is handy as a reminder and that is all.
Again from numerous observations in simulators during type rating training where the PM who makes the support calls is quietly told by the instructor, to "forget" to call VR, we have seen some alarmingly hesitant delays by the PF who then fails to rotate at the correct VR because he momentarily disbelieves his own ASI simply because of no call by the PM.
In other words he was waiting until being told by the PM to rotate The worst I saw was the PF staying on the runway 37 knots after the bugged VR because he was waiting for the PM to call "Rotate". As we went into the overrun and through the localiser aerials, the PF looked across the cockpit at the PM and said accusingly "You forgot to call `Rotate`"
A smart pilot will always have an eye on the ground speed reading nearing VR and knows what its approximate indication should be approaching the airspeed check at 80 knots (737) and especially nearing VR. The PM support calls during the take off roll will always be with us but as said earlier, they are back up only - not necessarily action calls.
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Centaurus, JT, all
Interesting comments to say the least. The cert numbers should never even shown anywhere. I feel they have little basis or foundation in reality, and just serve to confuse the issue. When was the last time your MLW 737-800 was on final at a sea level airport, ISA temp, flaps 40, at 140kts at the FAF?
In designing RNP procedures, specifically the missed and EO missed, a flight validation is required of the procedure. After seeing a few of these, it is something that every pilot should go thru, and at multiple locations. Flight val uses the assumption that putting one engine on idle, is the same as EO.
These procedures are coded, so the aircraft has everything it needs to know about the real-time conditions. Now see the momentary descent calcs, and actual climb rates.
The movement to MDA is certainly justified, but unfortunately, it was not followed thru on what the decision altitude should be, but simply leaves it up to the operator to decide when to initiate GA, and not bust the MDA.
The assumption of 50 foot momentary descent is a joke, for any aircraft, and even 100 foot is virtually impossible if one is EO.
Interesting comments to say the least. The cert numbers should never even shown anywhere. I feel they have little basis or foundation in reality, and just serve to confuse the issue. When was the last time your MLW 737-800 was on final at a sea level airport, ISA temp, flaps 40, at 140kts at the FAF?
In designing RNP procedures, specifically the missed and EO missed, a flight validation is required of the procedure. After seeing a few of these, it is something that every pilot should go thru, and at multiple locations. Flight val uses the assumption that putting one engine on idle, is the same as EO.
These procedures are coded, so the aircraft has everything it needs to know about the real-time conditions. Now see the momentary descent calcs, and actual climb rates.
The movement to MDA is certainly justified, but unfortunately, it was not followed thru on what the decision altitude should be, but simply leaves it up to the operator to decide when to initiate GA, and not bust the MDA.
The assumption of 50 foot momentary descent is a joke, for any aircraft, and even 100 foot is virtually impossible if one is EO.
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In an attempt to credit those here who have been discussing (even though it may have sounded argumentative) whether or not V1 is really a “decision” speed – or more toward the discussion (argument) – whether or not it is the speed at which a “decision” is made as to whether or not an abort should be initiated. Clearly, THAT specific airspeed is described, at least by the regulator (in the US anyway – and by implication, elsewhere, if we’re discussing a US-built aircraft flown under another country’s regulations), as being a speed that has to be viewed through two (2) perspectives:
1) the first perspective is the perspective of an ‘engine failure’ speed (called VEF) where the speed under discussion (argument) MAY NOT be less than this ‘engine failure’ speed AND it cannot be less than the minimum ground control speed (VMCG) … and it is selected by the person(s) applying for the certification; and
2) the second perspective is a bit more practical in that it must be chosen on the basis of not being less than the ‘engine failure’ speed (described above) but it must include any speed that is gained with the critical engine failed, during the time interval between the instant at which the engine is failed and the instant at which the pilot, having recognized the failure, takes the first action to reject the takeoff – and that recognition is defined by the pilot applying brakes, reducing thrust, deploying speed brakes, etc.
So, in the strict understanding of the “noun-verb-object-subject” kind of thinking, V1 is the speed at which a decision, having been made previously, is expressed by outward, recognizable, action. Of course, if the “decision” that is made is to CONTINUE the takeoff, there would be no outward, recognizable, action taken by the pilot, in that he/she would simply continue what he/she had been doing up to that point.
Now, I’ve known some folks who, having been born and bread in the US “southern” states (where, historically anyway, it does often take longer to say virtually anything) do, in fact speak more slowly. Some describe it as ‘deliberately.’ Unfortunately, and incorrectly, sometimes this characteristic has been rumored to be due to an absence of intelligence or proficiency in the spoken language … however, having lived in the US “south” for most of my life personally, I KNOW that any slowness of speech is due directly to the physical exertion required – and, being in the south, where the ambient temperatures get to those typical of a “southern climate,” virtually no one desires to work muscles at a rate that would tend to generate more internal body heat … and that includes a deliberate choice to speak more slowly than do our “northern” neighbors. At least, that’s my story … and I’m stickin’ to it, ya’ll!
But, be that as it may, the time it takes to say “V-1”, out loud, even if you’re a “southerner,” doesn’t take anywhere near as long as some believe it does. I’m NOT saying that if you or your airline desires to call V1 at a lesser speed … that an accident surely cannot be avoided. All I’m saying is that individually choosing some arbitrary point below which some things are more likely NOT to happen … and above which other things are more likely TO happen … is a pretty poor way to approach the understanding of the aerodynamics under which the airplane you’re piloting was certificated.
The bottom line I think is this:
TRUE enough … these “chart speeds” are speeds generated during the certification process. But they translate, and do so directly, into day-to-day operations of your airplane. A knot or two here or there … a second or two there or here … are not likely to cause or prevent any specific result. Tires wear … contaminants build up on runways … brakes wear and get hot and “out-of-round” … runways have hills and valleys … temperatures on the runway are different than what is “reported” by the tower … wings get dented ... and list goes on and on and on. But at some point, there has to be some specific parameters that simply have to be chosen and we owe it to ourselves and to the profession to follow those parameters. What is the purpose of having that information if it is thought to be irrelevant or immaterial? If we’re going to be professional and do what we’re supposed to do … I think we have to make the best of what we’ve been taught, what we are given, and put it all together in the proper way, at the proper time, and do it all professionally. Anything else is simply NOT professional. We each have a choice to make … and I’ve made mine.
1) the first perspective is the perspective of an ‘engine failure’ speed (called VEF) where the speed under discussion (argument) MAY NOT be less than this ‘engine failure’ speed AND it cannot be less than the minimum ground control speed (VMCG) … and it is selected by the person(s) applying for the certification; and
2) the second perspective is a bit more practical in that it must be chosen on the basis of not being less than the ‘engine failure’ speed (described above) but it must include any speed that is gained with the critical engine failed, during the time interval between the instant at which the engine is failed and the instant at which the pilot, having recognized the failure, takes the first action to reject the takeoff – and that recognition is defined by the pilot applying brakes, reducing thrust, deploying speed brakes, etc.
So, in the strict understanding of the “noun-verb-object-subject” kind of thinking, V1 is the speed at which a decision, having been made previously, is expressed by outward, recognizable, action. Of course, if the “decision” that is made is to CONTINUE the takeoff, there would be no outward, recognizable, action taken by the pilot, in that he/she would simply continue what he/she had been doing up to that point.
Now, I’ve known some folks who, having been born and bread in the US “southern” states (where, historically anyway, it does often take longer to say virtually anything) do, in fact speak more slowly. Some describe it as ‘deliberately.’ Unfortunately, and incorrectly, sometimes this characteristic has been rumored to be due to an absence of intelligence or proficiency in the spoken language … however, having lived in the US “south” for most of my life personally, I KNOW that any slowness of speech is due directly to the physical exertion required – and, being in the south, where the ambient temperatures get to those typical of a “southern climate,” virtually no one desires to work muscles at a rate that would tend to generate more internal body heat … and that includes a deliberate choice to speak more slowly than do our “northern” neighbors. At least, that’s my story … and I’m stickin’ to it, ya’ll!
But, be that as it may, the time it takes to say “V-1”, out loud, even if you’re a “southerner,” doesn’t take anywhere near as long as some believe it does. I’m NOT saying that if you or your airline desires to call V1 at a lesser speed … that an accident surely cannot be avoided. All I’m saying is that individually choosing some arbitrary point below which some things are more likely NOT to happen … and above which other things are more likely TO happen … is a pretty poor way to approach the understanding of the aerodynamics under which the airplane you’re piloting was certificated.
The bottom line I think is this:
TRUE enough … these “chart speeds” are speeds generated during the certification process. But they translate, and do so directly, into day-to-day operations of your airplane. A knot or two here or there … a second or two there or here … are not likely to cause or prevent any specific result. Tires wear … contaminants build up on runways … brakes wear and get hot and “out-of-round” … runways have hills and valleys … temperatures on the runway are different than what is “reported” by the tower … wings get dented ... and list goes on and on and on. But at some point, there has to be some specific parameters that simply have to be chosen and we owe it to ourselves and to the profession to follow those parameters. What is the purpose of having that information if it is thought to be irrelevant or immaterial? If we’re going to be professional and do what we’re supposed to do … I think we have to make the best of what we’ve been taught, what we are given, and put it all together in the proper way, at the proper time, and do it all professionally. Anything else is simply NOT professional. We each have a choice to make … and I’ve made mine.
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First, V1 is the maximum speed at which the rejected takeoff maneuver can be initiated and the airplane stopped within the remaining field length under the conditions and procedures defined in the FAR’s. It is the latest point in the takeoff roll where a stop can be initiated.
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AirRabbit, The V1 auto-callout on the A380 takes about half a second and the V1 speed is reached at the end of the auto callout.
Seems perfectly reasonable to me.
Seems perfectly reasonable to me.
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I'd love to see a heavy weight takeoff, runway limited weight and climb limited weight, where the decision to continue was made at V1-15.
I think it would be quickly obvious that it's a dumb, and completely unsupported, technique.
I think it would be quickly obvious that it's a dumb, and completely unsupported, technique.
Last edited by misd-agin; 17th Feb 2014 at 14:15. Reason: added second sentence
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...and if, after that call (implying the decision having been made to continue) there were an engine failure to occur at, say V1-12, you would indeed see that such a decision at that point was just as you described!
