Reduced V1 on Dry Runway - (previously) Is V1min a Safety Benefit
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Jambo Buana
Little bit outside the EU, but the answer is NO. For dry runways, we stick to balanced field V-speeds.
Whilst the possibility of utilizing V1MIN exists using VMCG as the lower limit. I have never heard of anyone “arbitrarily” reducing V1=VMCG+1kts.
For example, using the B777 at MTOW
Minimum V1 is 36kts higher than V1MCG, as this is the minimum speed where the takeoff can be continued, an arbitrary reduction of V1 to V1MCG+1kt will result in that aircraft failing to achieve 35feet at the end of the runway, I would even hazard a guess that it wont be flying at all!
I think that you need to chat with the AA DEC and request further clarification.
Mutt
does any EU airline drop V1 to its minimum value, ie VMCG plus 1kt when possible?
Whilst the possibility of utilizing V1MIN exists using VMCG as the lower limit. I have never heard of anyone “arbitrarily” reducing V1=VMCG+1kts.
For example, using the B777 at MTOW
- Min V1 = 157.4 KIAS
- Max V1 = 163.0 KIAS
- Bal V1 = 160.2 KIAS
- V1MCG = 121.6 KIAS at 35.0 DEG C
Minimum V1 is 36kts higher than V1MCG, as this is the minimum speed where the takeoff can be continued, an arbitrary reduction of V1 to V1MCG+1kt will result in that aircraft failing to achieve 35feet at the end of the runway, I would even hazard a guess that it wont be flying at all!
I think that you need to chat with the AA DEC and request further clarification.
Mutt
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Tom,
I flew with a Boeing test pilot of 30 odd years on a recent C1 flight. I asked him a few questions and then whinged about pilots having so many theories on things. This is his qwote back to me, "son, theories are like xyzholes, everyone has one." Pretty nice I thought.
But what I am getting at is, that even in Boeing they have different theories on what we are talking about. I specifically asked a test pilot who was head of training standards 737 about calling V1 early. She said not to, that there was a 2 second reaction time for Mr Average etc.. So as time goes by the Boeing symposium you were at becomes history (which will repeat itself of course) and as new people take up their posts they forward their own theories.
This is a great game isnt it?
I flew with a Boeing test pilot of 30 odd years on a recent C1 flight. I asked him a few questions and then whinged about pilots having so many theories on things. This is his qwote back to me, "son, theories are like xyzholes, everyone has one." Pretty nice I thought.
But what I am getting at is, that even in Boeing they have different theories on what we are talking about. I specifically asked a test pilot who was head of training standards 737 about calling V1 early. She said not to, that there was a 2 second reaction time for Mr Average etc.. So as time goes by the Boeing symposium you were at becomes history (which will repeat itself of course) and as new people take up their posts they forward their own theories.
This is a great game isnt it?
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Hi Mutt,
I was just taking it to the theoretical limit of Vmcg+1kt. There must be occasions where Vmcg would be a lot closer than 36kts to a min V1. A very light BBJ for example.
If you compare my question to, reducing weight to achieve a contaminated RWY takeoff and thereby reducing V1 by 15 to 20 kts, you could reasonably expect, on long runways, that there is bags of extra performance available that would allow operators to reduce V1 by 10 to 20 kts lets say. Now this would provide a real safety benefit as you wouldnt get a really high energy RTO and crews are exposed to less time during which an RTO can be initiated.
2/3 of overruns are rejected unnecessarily in the first place! ref Boeing takeoff safety training guide.
I was just taking it to the theoretical limit of Vmcg+1kt. There must be occasions where Vmcg would be a lot closer than 36kts to a min V1. A very light BBJ for example.
If you compare my question to, reducing weight to achieve a contaminated RWY takeoff and thereby reducing V1 by 15 to 20 kts, you could reasonably expect, on long runways, that there is bags of extra performance available that would allow operators to reduce V1 by 10 to 20 kts lets say. Now this would provide a real safety benefit as you wouldnt get a really high energy RTO and crews are exposed to less time during which an RTO can be initiated.
2/3 of overruns are rejected unnecessarily in the first place! ref Boeing takeoff safety training guide.
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Originally Posted by Jambo Buana
If you compare my question to, reducing weight to achieve a contaminated RWY takeoff and thereby reducing V1 by 15 to 20 kts, you could reasonably expect, on long runways, that there is bags of extra performance available that would allow operators to reduce V1 by 10 to 20 kts lets say. Now this would provide a real safety benefit as you wouldnt get a really high energy RTO and crews are exposed to less time during which an RTO can be initiated.
2/3 of overruns are rejected unnecessarily in the first place! ref Boeing takeoff safety training guide.
2/3 of overruns are rejected unnecessarily in the first place! ref Boeing takeoff safety training guide.
So if one were to adopt a policy of routinely lowering V1 to (near) the minimum value, one would be increasing the risk of runway excursions to side, perhaps as fast as the risk of overruns was r\educed. (It's analagous to the practice of widespread reduced thrust takeoffs, reducing the real margin of takeoff performance)
