Would you abort after V1?
Think of the lowest v1 as the lowest speed you could safely continue the take off after an engine failure and the highest v1 as the highest speed from which you can stop
but... the issue in most overrun accidents is the timing of the effective actions to stop relative to intersecting the critical speed.
To continue requires much less motor skills.
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Thanks galaxy, I was thinking that myself. Putting in MTOW into the laptop to see a max V1 speed for the runway conditions - just really so that you have a mental idea of what you have remaining in terms of your balanced field speed reduction from a V1 stop situation. For instance at a light weight, v1 = 116, and the same at MTOW would be for example V1 = 149, but would you really want to delay VR to 149 in a ferry flight!
I am not advocating anything here, more that I want to know what margins we have been given when presented with a V1. I wonder if operators do not make this kind of data available in an easy format so that the stop/go decision is clear cut - rather than make it a 'greyer' area at lower weights as people could have 2 values to consider.
Interesting quote from that 'Pilot Guide to Takeoff Safety':
"By far, the most likely takeoff scenario for the
line pilot is the case where the actual airplane
weight is less than any limit weight, especially
the Field Length Limit Weight. It also is possibly
the most easily misunderstood area of takeoff
performance since the fact that the airplane is
not at a limit weight is about all the flight crew
can determine from the data usually available on
the flight deck. Currently, few operators provide
any information that will let the crew determine
how much excess runway is available; what it
means in terms of the V1 speed they are using;
or how to best maximize the potential safety
margins represented by the excess runway."
And another one w.r.t. tyre failure:
"McDonnell Douglas Corporation,
in an All Operator Letter4, has addressed this
dilemma by recommending a policy of not
rejecting a takeoff for a suspected tire failure
at speeds above V1−20 knots."
Is this out of date or used in any other type/fleet?
I am not advocating anything here, more that I want to know what margins we have been given when presented with a V1. I wonder if operators do not make this kind of data available in an easy format so that the stop/go decision is clear cut - rather than make it a 'greyer' area at lower weights as people could have 2 values to consider.
Interesting quote from that 'Pilot Guide to Takeoff Safety':
"By far, the most likely takeoff scenario for the
line pilot is the case where the actual airplane
weight is less than any limit weight, especially
the Field Length Limit Weight. It also is possibly
the most easily misunderstood area of takeoff
performance since the fact that the airplane is
not at a limit weight is about all the flight crew
can determine from the data usually available on
the flight deck. Currently, few operators provide
any information that will let the crew determine
how much excess runway is available; what it
means in terms of the V1 speed they are using;
or how to best maximize the potential safety
margins represented by the excess runway."
And another one w.r.t. tyre failure:
"McDonnell Douglas Corporation,
in an All Operator Letter4, has addressed this
dilemma by recommending a policy of not
rejecting a takeoff for a suspected tire failure
at speeds above V1−20 knots."
Is this out of date or used in any other type/fleet?
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Quote:
Think of the lowest v1 as the lowest speed you could safely continue the take off after an engine failure and the highest v1 as the highest speed from which you can stop
Agree
but... the issue in most overrun accidents is the timing of the effective actions to stop relative to intersecting the critical speed.
To continue requires much less motor skills.
Think of the lowest v1 as the lowest speed you could safely continue the take off after an engine failure and the highest v1 as the highest speed from which you can stop
Agree
but... the issue in most overrun accidents is the timing of the effective actions to stop relative to intersecting the critical speed.
To continue requires much less motor skills.
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From all the heated discussions, points, examples, etc offered on this thread... I think one thing has become obvious. It doesn't matter what you fly, when it comes time to think outside the box, I think most pilots do just that! In a Caravan, a bang above V1 means stop. In a Navajo, it depends where your decision point was, your weight, speed, incline, etc. In a Citation, I'm guessing the same would apply. In a 747, one bang is not serious, however 2 bangs would make you think "same engine, or 2 on the same side?".
All of these decisions depend on so many factors, it is unfair to try and compare airline pilots with anyone else.... it all depends on the factors relative at the time.
I think all SSG was trying to point out (initially) was this fact, but then got involved in a mud-slinging session with a whole bunch of people from other fields.
Bottom line is.... we all do what we think is correct at the time, according to the situation at the time. Our training does teach us different things, but we aren't just machines... we're humans, who assess things quite fast (normally), and, because we are humans, we are sometimes prone to making mistakes.
For me, V1 means "go". But that isn't true for every take-off... and my fellow crew-members know that, because I tell them... everytime, when it's relevant. Every take-off is different... no-one can dispute that.
SOME DAYS YOU'RE THE BUG... SOME DAYS YOU'RE THE WINDSHIELD
All of these decisions depend on so many factors, it is unfair to try and compare airline pilots with anyone else.... it all depends on the factors relative at the time.
I think all SSG was trying to point out (initially) was this fact, but then got involved in a mud-slinging session with a whole bunch of people from other fields.
Bottom line is.... we all do what we think is correct at the time, according to the situation at the time. Our training does teach us different things, but we aren't just machines... we're humans, who assess things quite fast (normally), and, because we are humans, we are sometimes prone to making mistakes.
For me, V1 means "go". But that isn't true for every take-off... and my fellow crew-members know that, because I tell them... everytime, when it's relevant. Every take-off is different... no-one can dispute that.
SOME DAYS YOU'RE THE BUG... SOME DAYS YOU'RE THE WINDSHIELD
A great deal of informed and erudite comment on this thread has been of considerable interest to a mere PPL like me (if I lose an engine my command decisions are pretty limited).
However one thing shines out very clearly from the discussion. V1 is being used for two different things - 'good-to-go minus one engine' and 'committed to take-off'. For low take-off weights and long runways these are often nowhere near the same value. Why has it evolved this way? Why can there not be an extra parameter in the take-off litany?
'V1' - 'Commit' - 'Rotate'
Then someone asks 'would you ever stop after 'commit' and the arguments go on ;-)
However one thing shines out very clearly from the discussion. V1 is being used for two different things - 'good-to-go minus one engine' and 'committed to take-off'. For low take-off weights and long runways these are often nowhere near the same value. Why has it evolved this way? Why can there not be an extra parameter in the take-off litany?
'V1' - 'Commit' - 'Rotate'
Then someone asks 'would you ever stop after 'commit' and the arguments go on ;-)
V1 is being used for two different things - 'good-to-go minus one engine' and 'committed to take-off'. For low take-off weights and long runways these are often nowhere near the same value. Why has it evolved this way? Why can there not be an extra parameter in the take-off litany?
It makes little difference in how hard you set it. The outcome is subjective (statistical)
As an example the incident/accident rates for takeoff aborts are typically calaculated for anything over 100kts, since the data gathering is unsure exactly when the pilot decided to start the abort.
Dont Hang,
The reason is that, particularly in large aircraft, a go decision has proven to be the safer option for almost all emergency situations even if, theoretically, you COULD stop on the available runway. High speed rejects are very serious manoeuvers. If the aircraft will fly it is virtually always safer to takeoff, circle, and land thus having the WHOLE runway to stop on, rather than just the bit left after V1.
lomapaseo-
It most certainly IS a rule according to the Ops Manual I am LEGALLY REQUIRED to operate in accordance with. As Captain, I do have the right to work outside the laid down procedures if it is necessary, but that means something has happened so that I CAN'T continue the takeoff.
The reason is that, particularly in large aircraft, a go decision has proven to be the safer option for almost all emergency situations even if, theoretically, you COULD stop on the available runway. High speed rejects are very serious manoeuvers. If the aircraft will fly it is virtually always safer to takeoff, circle, and land thus having the WHOLE runway to stop on, rather than just the bit left after V1.
lomapaseo-
V1 is not a rule, it's a guideline for judgements.
Last edited by Wizofoz; 24th Jun 2008 at 17:22. Reason: Shot my mouth off prematurely (Again!!)
Wizofoz
A trifle quick on the retort aren't we
You can express your own statements quite nicely and they will stand on their own. But please don't mess with mine, I'll be happy to back mine up anytime I feel it's necessary.
If it makes you feel any better I agree with what you said, but I do not retract my statements.
Sweeping, emotive statement not based in reality. It most certainly IS a rule according to the Ops Manual I am LEGALLY REQUIRED to operate in accordance with. As Captain, I do have the right to work outside the laid down procedures if it is necessary, but that means something has happened so that I CAN'T continue the takeoff, not that I don't fell like it! In your many guises you continually tell us your judgement is superior to the rulemakers, aircraft manufacturers and procedure designers whose job it is to give us data and procedures to safley fly.
No wonder you didn't get past those airline interviews.
No wonder you didn't get past those airline interviews.
You can express your own statements quite nicely and they will stand on their own. But please don't mess with mine, I'll be happy to back mine up anytime I feel it's necessary.
If it makes you feel any better I agree with what you said, but I do not retract my statements.
lomapaseo,
I apologize. I've only been dipping into this thread, and thought, wrongly, that you were another manifestation of SSG. Shows how one fool can muck it up for everyone!
Having read your posts in there entirety, I see you have a very firm grasp of the realities of the whole concept of V1 and Go/No go.
I apologize. I've only been dipping into this thread, and thought, wrongly, that you were another manifestation of SSG. Shows how one fool can muck it up for everyone!
Having read your posts in there entirety, I see you have a very firm grasp of the realities of the whole concept of V1 and Go/No go.
]
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Ay Ay Ay e jole
(That's espanish). Now that the cattle are off the runway, I'll drop the gear and squat. Observation. There is a sense here, and it isn't just because it's the "net", that way too many posters have skin thin enough to read the Guardian through. The quickest and loudest are usually the people who have the least to offer. I've done that, that's how I know to recognize it when I see it. So easy to angrily condemn a post, and then push one that wasn't worth the wait.
Maybe people are just too shy to begin new threads; I think that would help. More subjects, better venue, more thread integrity.
V1? Coffin Corner? Pilot's who pack? It's all good.
Airfoil
Maybe people are just too shy to begin new threads; I think that would help. More subjects, better venue, more thread integrity.
V1? Coffin Corner? Pilot's who pack? It's all good.
Airfoil
Last edited by airfoilmod; 24th Jun 2008 at 21:59. Reason: spell
lomapaseo,
I apologize. I've only been dipping into this thread, and thought, wrongly, that you were another manifestation of SSG. Shows how one fool can muck it up for everyone!
Having read your posts in there entirety, I see you have a very firm grasp of the realities of the whole concept of V1 and Go/No go.
I apologize. I've only been dipping into this thread, and thought, wrongly, that you were another manifestation of SSG. Shows how one fool can muck it up for everyone!
Having read your posts in there entirety, I see you have a very firm grasp of the realities of the whole concept of V1 and Go/No go.
I'm inclined to accept my limitations in communicating and prefer instead to let all posters express themselves and then take for myself the best of the communication.
I learn a lot from this, including to temper my own opinions.
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Simple Math
Why try to stop on 20 or 30 or 40 percent of a runway when you can take it in the air and come back and use nearly 100 percent of the runway to stop? There is a very good reason as to the WHY we train to GO after V1.
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Ok. I'm no pilot but isn't it abit stupid for a pilot to try and stop the plane with only 50 percent of the runway left?
I mean the speed of the plane will require more runway to stop and wouldn't the plane just simply go off the runway and crash?
I mean the speed of the plane will require more runway to stop and wouldn't the plane just simply go off the runway and crash?
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Ok. I'm no pilot but isn't it abit stupid for a pilot to try and stop the plane with only 50 percent of the runway left?
I mean the speed of the plane will require more runway to stop and wouldn't the plane just simply go off the runway and crash?
I mean the speed of the plane will require more runway to stop and wouldn't the plane just simply go off the runway and crash?
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Reject after v1
All aircraft manufacturers assume that the person reading the procedure is an average pilot, not a hotshot. That is to say they try to cover the whole community and not just a gifted few.
Almost all of the cases where a reject has been carried out after v1 have resulted in an overrun.
How would you decide in a matter of a couple of secs whether it would be safe to reject t.off after v1 on one rwy and not the other.
All a/cs are certified to fly on one eng and there are fire extinguishers to put out the fire.
And if it is possible to reject t.off and stop the a/c with the remaining length of the rwy then the calculation of the v1 is obviously incorrect, maybe the aerodynamics of the a/c do not permit to control the a/c at that speed for a reject.
So please, it is prudent as a community to have a procedure which in this case is to continue after v1. Maybe one will successfully reject the t.off and stop after v1, but it will be your last t.off i promise you , the training department will sack him without blinking.
Almost all of the cases where a reject has been carried out after v1 have resulted in an overrun.
How would you decide in a matter of a couple of secs whether it would be safe to reject t.off after v1 on one rwy and not the other.
All a/cs are certified to fly on one eng and there are fire extinguishers to put out the fire.
And if it is possible to reject t.off and stop the a/c with the remaining length of the rwy then the calculation of the v1 is obviously incorrect, maybe the aerodynamics of the a/c do not permit to control the a/c at that speed for a reject.
So please, it is prudent as a community to have a procedure which in this case is to continue after v1. Maybe one will successfully reject the t.off and stop after v1, but it will be your last t.off i promise you , the training department will sack him without blinking.
SSG or whatever name you go by......
How many 800,000 pound limiting runway take-offs have you done where 8000 feet of runway remaining is available. I'll bet you would have no doubt as to what to do at, or past, V1 in heavy weight widebody aircraft with a problem. Stopping is not an good idea, trust me. Yes, a Citation on a typical 8000 foot runway has a oodles of space and stopping is a possible, if uncalculated, outcome. But put it on 3500 feet, cliff at the end and a summer day and I doubt you would advocate stopping past V1 either.
GIVE IT UP!
How many 800,000 pound limiting runway take-offs have you done where 8000 feet of runway remaining is available. I'll bet you would have no doubt as to what to do at, or past, V1 in heavy weight widebody aircraft with a problem. Stopping is not an good idea, trust me. Yes, a Citation on a typical 8000 foot runway has a oodles of space and stopping is a possible, if uncalculated, outcome. But put it on 3500 feet, cliff at the end and a summer day and I doubt you would advocate stopping past V1 either.
GIVE IT UP!
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However, if folk are of the view that his/her posts represent only nuisance value, there remains the option of ignoring them .....
If, on the other hand, his/her posts stray into areas of unacceptable behaviour .. the outcome will be a programmed decision ...