Would you abort after V1?
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SSG
If you'd left it at the title then you would have got a different set of answers but you quite clearly gave us a scenario and asked for a response to it. You did not elaborate beyond that scenario and then instantly berated all of us who said continue for being robots.
We all answered your question correctly and you got all upset instead of accepting the answer and moving the discussion forward positively.
If you'd left it at the title then you would have got a different set of answers but you quite clearly gave us a scenario and asked for a response to it. You did not elaborate beyond that scenario and then instantly berated all of us who said continue for being robots.
We all answered your question correctly and you got all upset instead of accepting the answer and moving the discussion forward positively.
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BOAC
When I first got involved in this discussion SSG brought up a serious point one that had crossed my mind a few times on takeoff in a Citation approaching V1. That was "what sort of failure would make me as a Captain decide to ignore V1 and take my chances on the ground. Or even having rotated as with the 748 fire, put the aircraft back down again. Rememeber I was talking about a citation not a 747 and a citation on a runway where it could take off or land twice.
SSG i really feel that having started a valid discussion you are now coming over as being on some sort of Ego trip, I am cleverer than you sort of thing and you cannot let go.
The problem with forums are that they are faceless text. Text can be misread, misunderstood so my apologies if any of my text has come over wrong. My thanks to all the very experienced and clever people who have contibuted to making the subject clearer and so interesting.
On that I am bowing out of this thread as it has dried up for me and thanks to everyone
Pace
When I first got involved in this discussion SSG brought up a serious point one that had crossed my mind a few times on takeoff in a Citation approaching V1. That was "what sort of failure would make me as a Captain decide to ignore V1 and take my chances on the ground. Or even having rotated as with the 748 fire, put the aircraft back down again. Rememeber I was talking about a citation not a 747 and a citation on a runway where it could take off or land twice.
SSG i really feel that having started a valid discussion you are now coming over as being on some sort of Ego trip, I am cleverer than you sort of thing and you cannot let go.
The problem with forums are that they are faceless text. Text can be misread, misunderstood so my apologies if any of my text has come over wrong. My thanks to all the very experienced and clever people who have contibuted to making the subject clearer and so interesting.
On that I am bowing out of this thread as it has dried up for me and thanks to everyone
Pace
Last edited by Pace; 20th May 2008 at 09:38.
No SSG,
You set the tone by asking a question then preaching/insulting experienced pilots giving you an answer. I'm not tapping out of this thread as I'm interested to see where you go from here. Having alienated your only ally in Pace in such an insulting way I look forward to your next move.
You set the tone by asking a question then preaching/insulting experienced pilots giving you an answer. I'm not tapping out of this thread as I'm interested to see where you go from here. Having alienated your only ally in Pace in such an insulting way I look forward to your next move.
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so let me get this straight;
if you got a flap asymmetry warning, an un-commanded slat retraction, a trim runaway, an obvious control jam or hard-over, a double engine flame out, (if you only had two for the less astute among you) after V1 you would not even consider aborting the take off because you had said so???
I have no issue with SOP's but if you cannot think outside the box you should not be in it. I am with SSG here.
if you got a flap asymmetry warning, an un-commanded slat retraction, a trim runaway, an obvious control jam or hard-over, a double engine flame out, (if you only had two for the less astute among you) after V1 you would not even consider aborting the take off because you had said so???
I have no issue with SOP's but if you cannot think outside the box you should not be in it. I am with SSG here.
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My next move....hmmm
Well I was sitting here, pretty much ignoring most of what you said...then my cat hopped up onto the keyboard...I got to thinking...
If all there is to a take off judgement is to pull the levers before V1, push them forward after V1,...can a cat be taught that?
I mean cat's have terrific reflexes, are very fast...and if all they have to do is watch the airspeed indicator for V1...maybe we could put a little mouse on the levers to keep her interested...corporate will love the low costs, they never get sick and they work for kibble.
If all there is to a take off judgement is to pull the levers before V1, push them forward after V1,...can a cat be taught that?
I mean cat's have terrific reflexes, are very fast...and if all they have to do is watch the airspeed indicator for V1...maybe we could put a little mouse on the levers to keep her interested...corporate will love the low costs, they never get sick and they work for kibble.
Pilotbear,
I don't believe anyone has said that they would would always continue after V1. They have answered the original question with reference to engine fire and because it does not fit the "SSG model" they have been flamed for it.
BTW that post was aimed at SSG because of the uncalled rudeness to Pace, who left the arena in a composed way.
There is no doubt that there are situations that we think outside the box and use our best judgement at the time. That is why if their is sim time left at the end of a check we always try to throw something unusual at the crew.
I don't believe anyone has said that they would would always continue after V1. They have answered the original question with reference to engine fire and because it does not fit the "SSG model" they have been flamed for it.
BTW that post was aimed at SSG because of the uncalled rudeness to Pace, who left the arena in a composed way.
There is no doubt that there are situations that we think outside the box and use our best judgement at the time. That is why if their is sim time left at the end of a check we always try to throw something unusual at the crew.
Mach 3
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http://www.smartcockpit.com/pdf/flig...erodynamics/28
In principle, I agree with one V1 per T/O.
But in extremis (which is the point of the discussion isn't it?), with a V1 split of ~30kts....
Reminds me of that Eddie Izard sketch, "Cake or Death"...
http://www.youtube.com/watch?v=BNjcuZ-LiSY
Of course, what complicates things is Vr...
In principle, I agree with one V1 per T/O.
But in extremis (which is the point of the discussion isn't it?), with a V1 split of ~30kts....
Reminds me of that Eddie Izard sketch, "Cake or Death"...
http://www.youtube.com/watch?v=BNjcuZ-LiSY
Of course, what complicates things is Vr...
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SR71
Great link to the Boeing sit on min and max V1...I learned something!!!
Question.....if balanced field for the day is 5000ft on a ten thousand ft runway...could you calculate max V1 to just make the stopway on a rejected take off on that runway?
Question.....if balanced field for the day is 5000ft on a ten thousand ft runway...could you calculate max V1 to just make the stopway on a rejected take off on that runway?
SSG, on my aircraft you can select whichever V1 suits you. Our performance gives mean V1 for starters but we can also check (& use if need be) the min & max V1 to suit the situation.
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could you calculate max V1 to just make the stopway on a rejected take off on that runway?
Some aircraft its easy, others not so easy... all depends on the year of manufacture and the available software.
Mutt
Ssg--V1 is advisory-if the aircraft is uncontrollable then we'd all abort and take the 50/50 chance of dying common sense but in 99.999% of cases no--simple--that's why you have to love this game you alway have a chance to die!!!oh well better than dying on the ground-I guess
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Well
I have to admit that going to the Boeing link opened up my eyes..see my post on Flex ops.. Infact I invented a new V speed...I'm not kidding....
I don't think a post V1 abort wouldn't be so iffy with 7000 ft of runway left, a 1000 ft stopway, and miles of Iowa cornfield beyond...
I don't think a post V1 abort wouldn't be so iffy with 7000 ft of runway left, a 1000 ft stopway, and miles of Iowa cornfield beyond...
Stealing my post a few pages back on refusal speed. If you don't recognize the term, I refer you to ground school. I will agree with the idea of stopping in the instance when V1 and Vr are "split" IF you know you can stop in the TODA and have the brake energy available. However, few civil planes have refusal speed charts or, for that matter, any relevant performance charts. In my old C-5 engineers computed about 50 entries in the take-off data sheet, including Vmca, Vmcg, take-off ground run (all 4 running) gradients, refusal speed, brake energy, climb capability on 4, 3, and 2 engines. A bit anal,but if you knew performance, good stuff. You cannot eyeball, in high performance airplanes, the take-off. The Force is with Luke, not you.
Would I abort after V1, yes, if the plane was uncontrollable (flight control problem) or suffered an extreme failure, say an engine explosion. If an engine fire lite came on as I went thru V1 and accelerating-NO. We're not trained that way, it is not briefed that way and the briefing is where critical decisions are made, not thundering down the runway making it up as one goes along.
For example, an old friend had a severe tire failure taking out most a bogey on a 707, after V1 and airplane stopped accelerating, stuck short of Vr. All went for brief swim in SFO bay. Two different friends have taken different C-5s airborne after bird strikes during rotation, one with 200,000 pounds of Class A explosives on-board). Both came around and landed under control with no damage. Aborts would have certainly overrun the available runway, the take-offs were that close and they lost one engine and significant thrust on the one other. A CO DC-10 did something similar in EWR and landed.
If you want a better idea, consider this: review the data available, using a runway analysis, determine the heaviest weight acceptable for the runway, IF the V1 for that weight equals or exceeds Vr for the planned take-off weight; set V1 equal to Vr. Yes, you have "unbalanced" the field length, not operating IAW with the training and FAA certification, and the insurers might disown you, but I'm guessing it will at least provide a logical justification for your operation. A few giggles, too.
At an airline I worked for, SSG, your mode of work was called, "in business for yourself".
PS: if you dare bring up the recent C-5 accident, the response is: THEY OPERATED LIKE YOU WANT TO--Unbriefed, uncoordinated, and poor technique under stress. The plane was perfectly flyable, IF they flew as trained by the book.
Mutt: I agree-few civil planes have the charts available for what is needed.
Would I abort after V1, yes, if the plane was uncontrollable (flight control problem) or suffered an extreme failure, say an engine explosion. If an engine fire lite came on as I went thru V1 and accelerating-NO. We're not trained that way, it is not briefed that way and the briefing is where critical decisions are made, not thundering down the runway making it up as one goes along.
For example, an old friend had a severe tire failure taking out most a bogey on a 707, after V1 and airplane stopped accelerating, stuck short of Vr. All went for brief swim in SFO bay. Two different friends have taken different C-5s airborne after bird strikes during rotation, one with 200,000 pounds of Class A explosives on-board). Both came around and landed under control with no damage. Aborts would have certainly overrun the available runway, the take-offs were that close and they lost one engine and significant thrust on the one other. A CO DC-10 did something similar in EWR and landed.
If you want a better idea, consider this: review the data available, using a runway analysis, determine the heaviest weight acceptable for the runway, IF the V1 for that weight equals or exceeds Vr for the planned take-off weight; set V1 equal to Vr. Yes, you have "unbalanced" the field length, not operating IAW with the training and FAA certification, and the insurers might disown you, but I'm guessing it will at least provide a logical justification for your operation. A few giggles, too.
At an airline I worked for, SSG, your mode of work was called, "in business for yourself".
PS: if you dare bring up the recent C-5 accident, the response is: THEY OPERATED LIKE YOU WANT TO--Unbriefed, uncoordinated, and poor technique under stress. The plane was perfectly flyable, IF they flew as trained by the book.
Mutt: I agree-few civil planes have the charts available for what is needed.
Quote of ssg’s original scenario:
Assume you have 5000 ft extra runway past your balanced field length, your light, cool weather, everything is in your favor...you accelerate past V1 twards V2, and you get an engine fire...
Would you fly it off the ground or try to stop it?
[Unquote]
Not sure if you’re a pilot, ssg, but you certainly made us all examine our principles and understanding of take-off performance. No bad thing. But there are at least two factors in your scenario that you seem to have overlooked.
1) Once VR has been called and rotation initiated, there is a major handling issue, as others have commented. [Granted V1 can be 30kts below VR.]
2) Bringing the aircraft safely to a halt on the runway with an engine fire is not necessarily non-fatal. If an engine fire occurs before V1, we must also assume thrust failure; so performance theory suggests continuing is not normally an option (unless someone wants to propose that on another thread). In that case we must settle for extinguishing the fire at a standstill − backed up by the fire service. Think of the B737 at Manchester, when a light crosswind blew the flames into the fuselage. After V1, even assuming the crew has a choice, taking the fire into the air may be the safer way of handling the fire. Trouble is, there are engine fires and engine fires. Perhaps other Posters will comment?
The scenario you have chosen is predictable at the planning stage. So the decision can be made then, by choosing V1 = VR (but NOT V2). When there is so much surplus runway, a big range of possible V1s is available (between BOAC’s Vgo and Vstop); provided your company’s performance manual or computer is up to the job… Having said that, you may decide to choose a low V1 if departing an airfield with no engineering support, for example, in a 4-engine aeroplane.
Once a V1 has been briefed, there has to be a very extreme failure to justify flouting it. The above performance calculation is always based on the failure of ONE engine, as in your scenario. A more difficult case would be the failure of more than one (before VR). Amending your scenario to the recognised fire and/or failure of 2 engines on a light DC10 before VR, I think most of us would hope to make the decision to close the throttles. In a 4-engine jet, it's not so clear-cut (we used to practise it in the VC10 simulator, but the second one didn’t quit until we had rotated).
Assume you have 5000 ft extra runway past your balanced field length, your light, cool weather, everything is in your favor...you accelerate past V1 twards V2, and you get an engine fire...
Would you fly it off the ground or try to stop it?
[Unquote]
Not sure if you’re a pilot, ssg, but you certainly made us all examine our principles and understanding of take-off performance. No bad thing. But there are at least two factors in your scenario that you seem to have overlooked.
1) Once VR has been called and rotation initiated, there is a major handling issue, as others have commented. [Granted V1 can be 30kts below VR.]
2) Bringing the aircraft safely to a halt on the runway with an engine fire is not necessarily non-fatal. If an engine fire occurs before V1, we must also assume thrust failure; so performance theory suggests continuing is not normally an option (unless someone wants to propose that on another thread). In that case we must settle for extinguishing the fire at a standstill − backed up by the fire service. Think of the B737 at Manchester, when a light crosswind blew the flames into the fuselage. After V1, even assuming the crew has a choice, taking the fire into the air may be the safer way of handling the fire. Trouble is, there are engine fires and engine fires. Perhaps other Posters will comment?
The scenario you have chosen is predictable at the planning stage. So the decision can be made then, by choosing V1 = VR (but NOT V2). When there is so much surplus runway, a big range of possible V1s is available (between BOAC’s Vgo and Vstop); provided your company’s performance manual or computer is up to the job… Having said that, you may decide to choose a low V1 if departing an airfield with no engineering support, for example, in a 4-engine aeroplane.
Once a V1 has been briefed, there has to be a very extreme failure to justify flouting it. The above performance calculation is always based on the failure of ONE engine, as in your scenario. A more difficult case would be the failure of more than one (before VR). Amending your scenario to the recognised fire and/or failure of 2 engines on a light DC10 before VR, I think most of us would hope to make the decision to close the throttles. In a 4-engine jet, it's not so clear-cut (we used to practise it in the VC10 simulator, but the second one didn’t quit until we had rotated).
Chris: Hope "low" V1 is referenced to Vmcg.
One thought not brought to light. I am taking off between V1 and Vr, experience an engine failure/fire-unknown immediately is the loss of Sys 2 hydraulic power due to damage. Now, in my current steed, I'm down to 50% brakes-big loss of stopping power. If it were Sys 3, I'd have 50% brakes and no steering (yes, differential brakes, but further degrades stopping). Heavy transports frequently have lots of other system problems that would best be defined, handled and planned for airborne. Once airborne, the emergency landing will be accompanied by CFR, flight attendants will be ready for an evacuation, all aircraft problems will have been addressed. The approach can be planned so the crew/ATC is ready. I just believe the airplane is safer airborne unless it cannot get there. SSG-as opposed to the Citation (I have about 2800 hours in them) most transports, even large corporate jets, just do not always operate with oodles of extra runway. I have done plenty of take-offs in the GLEX at heavier weights where we didn't 3000 feet extra. And we use APG perf calculations on every take-off. Hell, on the Kennedy Skid Strip or Edwards AFB, I'd do lots of things with an engine failure. EDW is 13,000 long by 300 wide and goes into Muroc Lake Bed.
One thought not brought to light. I am taking off between V1 and Vr, experience an engine failure/fire-unknown immediately is the loss of Sys 2 hydraulic power due to damage. Now, in my current steed, I'm down to 50% brakes-big loss of stopping power. If it were Sys 3, I'd have 50% brakes and no steering (yes, differential brakes, but further degrades stopping). Heavy transports frequently have lots of other system problems that would best be defined, handled and planned for airborne. Once airborne, the emergency landing will be accompanied by CFR, flight attendants will be ready for an evacuation, all aircraft problems will have been addressed. The approach can be planned so the crew/ATC is ready. I just believe the airplane is safer airborne unless it cannot get there. SSG-as opposed to the Citation (I have about 2800 hours in them) most transports, even large corporate jets, just do not always operate with oodles of extra runway. I have done plenty of take-offs in the GLEX at heavier weights where we didn't 3000 feet extra. And we use APG perf calculations on every take-off. Hell, on the Kennedy Skid Strip or Edwards AFB, I'd do lots of things with an engine failure. EDW is 13,000 long by 300 wide and goes into Muroc Lake Bed.
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Good Posts..
I think we can all agree that taking off from a 5000 ft field in a 737, balanced field is 5000 ft...20000 hour trend monitored engines, burning lake of lava at the end.... Is a little different then a Citation on a 12000 ft field, balanced field is 3000 ft, Iowa cornfields for miles., and new engines with 100 hours on them....
The later shows that the pilot has more discretion because he has more time, more options...To purposely take away those options by choosing a shorter runway, using Flex, adding weight...adds risk...I didn't say dangerous, I said risk...
I beleive that 'Pilot Discretion' is a problem for many in here...they want the pilot to have the numbers, the facts...not just look at the airspeed and runway remaining and make a call..the more they keep him from making a decision and just going to the checklist, they feel the flight will be less prone to a screwup.....I can understand that...
But stories abound of pilots that made quick descisions that saved lives that weren't on the checklist or calculated ahead of time, and we have seen the opposite as well...if anyone in here can brief for all possible scenarios, my hat's off to you...
History judges hard the ignorant...and luck favors the prepared...
Seems we are always finding a way to crash a plane who's problem wasn't on the checklist or the checklist was wrong when you encountered it...but we move forward by the ensuing discussion and learn from our mistakes...
Personaly discussing these scenarios and hashing them out ahead of time, looking at all the angles is better then waiting for another accident then trying to figure out what went wrong and adding another line on the checklist.
I have commented sadly to students, that someone had to die for every line on a checklist...and the checklists keep getting longer.....
They get longer because many times we encounter some form of ignorance, something that everyone overlooked, or outmoded concepts and training that needed to change... but again, a plane had to crash to uncover that hidden truth.
I feel these forums are a better way to uncover that truth....
The later shows that the pilot has more discretion because he has more time, more options...To purposely take away those options by choosing a shorter runway, using Flex, adding weight...adds risk...I didn't say dangerous, I said risk...
I beleive that 'Pilot Discretion' is a problem for many in here...they want the pilot to have the numbers, the facts...not just look at the airspeed and runway remaining and make a call..the more they keep him from making a decision and just going to the checklist, they feel the flight will be less prone to a screwup.....I can understand that...
But stories abound of pilots that made quick descisions that saved lives that weren't on the checklist or calculated ahead of time, and we have seen the opposite as well...if anyone in here can brief for all possible scenarios, my hat's off to you...
History judges hard the ignorant...and luck favors the prepared...
Seems we are always finding a way to crash a plane who's problem wasn't on the checklist or the checklist was wrong when you encountered it...but we move forward by the ensuing discussion and learn from our mistakes...
Personaly discussing these scenarios and hashing them out ahead of time, looking at all the angles is better then waiting for another accident then trying to figure out what went wrong and adding another line on the checklist.
I have commented sadly to students, that someone had to die for every line on a checklist...and the checklists keep getting longer.....
They get longer because many times we encounter some form of ignorance, something that everyone overlooked, or outmoded concepts and training that needed to change... but again, a plane had to crash to uncover that hidden truth.
I feel these forums are a better way to uncover that truth....
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rubbish!
having witnessed at close quarters the development and certification of a QRH for a new type before it's entry into service I can categorically state that no one died during the whole process. Nor have they died in the revisions of said QRH.
God help your students!
having witnessed at close quarters the development and certification of a QRH for a new type before it's entry into service I can categorically state that no one died during the whole process. Nor have they died in the revisions of said QRH.
God help your students!
Ssg, could you comment as Mutt has brought up on the 15' wet screen height as well the four[I think] different possible certification scenarios and how they would work against your pax too----? compare and contrast 
Also explain to me what are the basics of the segmented takeoff profile?-because a 4000'/min segmented climb oei at V2 wow
although you've got us going man---
PA
Also explain to me what are the basics of the segmented takeoff profile?-because a 4000'/min segmented climb oei at V2 wow
although you've got us going man---
PA
Last edited by Pugilistic Animus; 20th May 2008 at 20:19.