Call V1 3 to 5kts prior
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It's all to do with the fact that V1 is a maximum 'brakes on' speed if you decide to carry out an RTO. If the decision process starts at V1 and the decision is then made to RTO, the brakes on speed would be above V1.
Boeing state that the decision to carry out an RTO must be made prior to V1 and the first action (thrust levers closed, brakes on) must be carried out at, or prior to, V1.
Different carriers cater for this in different ways. Some call V1 slightly early, others will always use the WET V1 figure, even on a bare/dry runway. Ours just emphasises that the decision to RTO has to be made prior to V1 and that the RTO must be commenced by V1.
As an airmanship point it is always important to know what your limiting performance criteria is. Eg, if you are climb limited you will have some spare stopping performance in hand but if you are field length limited then a V1 RTO will leave you in very close proximity to the wrong end of the runway.
Boeing state that the decision to carry out an RTO must be made prior to V1 and the first action (thrust levers closed, brakes on) must be carried out at, or prior to, V1.
Different carriers cater for this in different ways. Some call V1 slightly early, others will always use the WET V1 figure, even on a bare/dry runway. Ours just emphasises that the decision to RTO has to be made prior to V1 and that the RTO must be commenced by V1.
As an airmanship point it is always important to know what your limiting performance criteria is. Eg, if you are climb limited you will have some spare stopping performance in hand but if you are field length limited then a V1 RTO will leave you in very close proximity to the wrong end of the runway.
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The logic is that if you start saying "v1" 3 -5 seconds prior to hitting the speed, the pilot flying knows that you have reached V1 when you finish saying "v1". If you start to call v1 once you reach v1, by the time you finish saying it you are past it and therefore no longer in a position to make a "go-no go" decision.
Anyhow, that's the idea.
Anyhow, that's the idea.
Different carriers cater for this in different ways. Some call V1 slightly early, others will always use the WET V1 figure, even on a bare/dry runway. Ours just emphasises that the decision to RTO has to be made prior to V1 and that the RTO must be commenced by V1.
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I dunno about others, but we say "Vee One" at V1, 'Vee Rrrr, Rotate to XXX degrees" at VR, and call out V2 as it passes. Target climb V2+10.
No need to call anything prior, and it all happens soon enough.
No need to call anything prior, and it all happens soon enough.
Calling V1 at-5 kts is standard practice with my airline.
As already stated, to ensure that a reject is not started above V1.
By the time you have said it it's too late to stop (unless you are 'ssg')
As already stated, to ensure that a reject is not started above V1.
By the time you have said it it's too late to stop (unless you are 'ssg')
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Quite a few aircraft in our fleet call V1 on their own (V1-autocall), only call the PM has to do in that case is "Rotate". If we do not have automatic V1 calls we have to do it ourselves. No response on either call is required, but at V1 the CPT has to remove his hands from the thrust levers, and on "Rotate" of course rotation has to be started.
Personally i was trained to start saying V1 3kts earlier, however that is not SOP in my current company so i just do what they require.
Personally i was trained to start saying V1 3kts earlier, however that is not SOP in my current company so i just do what they require.
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LaGuardia Takeoff
If you took off from LaGuardia you would understand this procedure. Runway is short and a nice pool of water is waiting for you at the end. Totally makes sense.
Last time I plugged in the numbers in the MCDU, we had only 6 feet of accelerated stop distance remaining if we decided to abort exactly at V1. Do I want to abort in the case right at V1? I don't think so. Remember this is based on perfect conditions.
Last time I plugged in the numbers in the MCDU, we had only 6 feet of accelerated stop distance remaining if we decided to abort exactly at V1. Do I want to abort in the case right at V1? I don't think so. Remember this is based on perfect conditions.
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never thought it neccesary to call V are and Vee two---some SOPs require it though
I'm one of those who responds with a thank you or precedes with a please. I don't see that as extraneous or out of line, but I've sure met a few who had a fit because those "extra words" were apparently just too much to handle. When I say "Set reduced thrust," and the FE responds "reduced thrust set," I reply "thank you." It's not in our standard callouts. I did it in the sim and got loudly berated by the check airman. That individual felt that any extra syllables might bring down the four horses of the apocalypse and perhaps a small infestation of rodents. I don't think common courtesy is out of line.
I sat down with an old salt FE one day who said "You can call me anything you like but I expect a please and thank you." I respect that, and try to give it anyway. Even if it's an extra word.
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As Bananasx2 states the problem comes from being field limited. If you are and you call V1 early do, you enough runway to accelerate to Vr and clear the screen height in the event of an engine failure between your artificially reduced V1 and Vr? Possibly not. I think the Boeing verbiage is that a stop must be initiated by V1 but the mechanics of it allow for a certain amount of 'thinking time'. There is a value laid down but I can't lay my hands on it currently and it is therefore understood that the aircraft may accelerate beyond V1 by a certain margin before the stop is initiated. I have seen written in several manuals that a stop initiated at V1 on a limiting runway may result in the aircraft not coming to rest on the paved surface. This is due to the calculations being made for a perfect aircraft, on the perfect day, by the perfect pilot and we all know there is no such thing as the perfect aircraft or the perfect day!
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Yes, with the current price of fuel we are using Flex takeoffs. Obviously, if anything seem out of place we go to TOGA. No questions asked.
It is not the first time I takeoff from short runways and a pool of water (aka LGA) and every time the software gives you performance numbers right on the edge for the most optimum Flex temperature. 2 weeks ago, I remember the accelerate stop distance remaining being 1 feet! You can imagine how our briefing went...
It is not the first time I takeoff from short runways and a pool of water (aka LGA) and every time the software gives you performance numbers right on the edge for the most optimum Flex temperature. 2 weeks ago, I remember the accelerate stop distance remaining being 1 feet! You can imagine how our briefing went...
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Well on the 'Bus the autocall is a couple of knots or so before V1, and it's NOTHING to do with incapacitation.... It's just that if you are length limited it stops you from over running if you start the abort at V1 - it takes a couple of seconds to even DECIDE to stop - by then you're V1 PLUS X kts and you're possibly stuffed...
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v1
I think 2 seconds of reaction time should be allowed for in the v1 calculation. Dont know where I got it from but it came up when I read the discussion.
Not much but at least something
Not much but at least something
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It's all to do with the fact that V1 is a maximum 'brakes on' speed if you decide to carry out an RTO. If the decision process starts at V1 and the decision is then made to RTO, the brakes on speed would be above V1.
Boeing state that the decision to carry out an RTO must be made prior to V1 and the first action (thrust levers closed, brakes on) must be carried out at, or prior to, V1.
Boeing state that the decision to carry out an RTO must be made prior to V1 and the first action (thrust levers closed, brakes on) must be carried out at, or prior to, V1.
§ 25.107 Takeoff speeds.
(a) V1must be established in relation to VEFas follows:
(1) VEFis the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under §25.149(e).
(2) V1, in terms of calibrated airspeed, is selected by the applicant; however, V1may not be less than VEFplus the speed gained with critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognizes and reacts to the engine failure, as indicated by the pilot's initiation of the first action (e.g., applying brakes, reducing thrust, deploying speed brakes) to stop the airplane during accelerate-stop tests.
(a) V1must be established in relation to VEFas follows:
(1) VEFis the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under §25.149(e).
(2) V1, in terms of calibrated airspeed, is selected by the applicant; however, V1may not be less than VEFplus the speed gained with critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognizes and reacts to the engine failure, as indicated by the pilot's initiation of the first action (e.g., applying brakes, reducing thrust, deploying speed brakes) to stop the airplane during accelerate-stop tests.