Post V1 rejected take off...yeah or neah?
Thread Starter
Join Date: Mar 2010
Location: NW
Posts: 269
Likes: 0
Received 0 Likes
on
0 Posts
Post V1 rejected take off...yeah or neah?
Your just past V1, a fuel truck zips by, clips your right side somewhere, you hear a bang...plane is still going straight down the runway....do you pull the aircraft off, or try to stop it...
Serious replies and reasons please.
Serious replies and reasons please.
Join Date: Nov 2007
Location: United Kingdom
Age: 71
Posts: 713
Likes: 0
Received 0 Likes
on
0 Posts
I'd like to think that we might have seen the offending fuel truck prior to reaching V1. After all, he's probably not doing more than 30 mph and we're doing something like 100 kts... you'd have a few distinct clues that you were heading for a collision; prior to V1.
You want a serious reply? It's a bit of a nonesense hypothetical situation! If, as you say, that you're past V1; you're going to take the fuel truck with you beyond the end of the runway/stopway.
You want a serious reply? It's a bit of a nonesense hypothetical situation! If, as you say, that you're past V1; you're going to take the fuel truck with you beyond the end of the runway/stopway.
Join Date: Apr 2004
Location: Erehwon
Posts: 1,146
Likes: 0
Received 0 Likes
on
0 Posts
Well Hoppy, as you well know, if everyone has done their jobs properly AND you are at performance limiting weights (masses), then it's really and truly dicing with death NOT to get airborne. There are so many variables - stopway etc etc
However, (there's always one isn't there) if you're light, V1/VR is unity you get there quickly (like ferry flights on a wet runway where you're committed to a full power take off perhaps), you've probably got enough runway to stop anyway. The key phrase in all this is:
"Performance Limiting"
Emerald Airways 748 (I think) is a famous example of what not to do and get away with it - you'll always hear of some exceptions.
However, (there's always one isn't there) if you're light, V1/VR is unity you get there quickly (like ferry flights on a wet runway where you're committed to a full power take off perhaps), you've probably got enough runway to stop anyway. The key phrase in all this is:
"Performance Limiting"
Emerald Airways 748 (I think) is a famous example of what not to do and get away with it - you'll always hear of some exceptions.
Thread Starter
Join Date: Mar 2010
Location: NW
Posts: 269
Likes: 0
Received 0 Likes
on
0 Posts
FO: Captain! A fuel truck just took of the right wing!
Capt: That's ok, you see we are past V1, a magical thing happens now...planes always fly...it doesn't matter if a bomb took the tail off, the wing fell off, we have 4 flat tires, or the control wheel came off in my hands...planes always fly after V1...when you have been flying as long as I have you will come to understand this....see it's written right here in the SOPs manual....
Capt: That's ok, you see we are past V1, a magical thing happens now...planes always fly...it doesn't matter if a bomb took the tail off, the wing fell off, we have 4 flat tires, or the control wheel came off in my hands...planes always fly after V1...when you have been flying as long as I have you will come to understand this....see it's written right here in the SOPs manual....
Join Date: Jan 2008
Location: Belgium
Age: 39
Posts: 36
Likes: 0
Received 0 Likes
on
0 Posts
SSG, all the answers towards the feasability of a post-V1 reject can be found here:
http://www.mobilit.fgov.be/data/aero...nts/AA-8-5.pdf
http://www.mobilit.fgov.be/data/aero...nts/AA-8-5.pdf
Join Date: Jun 2006
Location: Australia
Posts: 1,186
Likes: 0
Received 0 Likes
on
0 Posts
A more serious discussion can be had about the 80 knot airspeed call during the take off roll. Let me tell you what happens in the simulator. Assume captain PF. Passing 80 knots IAS, the PNF says nothing because he either was distracted looking at something or he simply was dreaming. By the time the PF realises there was no call the airspeed is now 100 knots so the PF calls "100 knots my side". F/O comes to life and says "Sorry 80 knots" Immediate confusion. The captain rejects the take off nearing V1. Was the reject necessary? Not really because if he had checked the ground speed at the same time the IAS passed 80 knots the captain would have known his airspeed indicator was operating normally.
The 80 knot call has become so routine that complacency sets in. And the one time there is a serious discrepancy you can be assured of instant confusion. By the time both pilots discover there is a problem the aircraft is rapidly accelerating to V1. Remember the Boeing advice re rejected take off and that is above 80 knots only reject in case of fire or fire warning, engine failure, predictive windshear and if the aircraft is unsafe or unable to fly.
Checking the expected ground speed reading at the 80 knot call is an excellent safety measure. Easier than checking the standby ASI reading in fact. When in doubt with perceived airspeed differences during the take off run call above 80 knots, a check of the expected ground speed can resolve the differences and if necessary because things happen so quickly, consider falling back on the ground speed reading to plan the rotation. Might be a lot safer than a high speed abort and the ground speed indicator doesn't care if the runway is wet or dry.
A Boeing recommendation is the PNF (or should I say PM!) makes call-outs based upon instrument indications etc The PF should verify and acknowledge. If the PM does not make the required callout, the PF should make it. An incident to an A330 illustrates the point. Unknown to the captain as PM the captain's ASI under-read significantly because of an insect blocking the tube. The F/O was PF. During the take off roll the F/O noticed the captain had not made the 100 knot call. Assuming the captain had forgotten the PF continued the take off and was near VR when the captain called "100 knots". Sensing an airspeed problem the captain took control and rejected the take off at high speed. Hot brakes and tyre deflation due heat then occurred.
If when the PF was passing 100 knots and no call from the PM, the PF had called "110 knots my side" (allowing for acceleration), the ASI discrepancy would have been discovered much earlier. Better still, had the captain noticed his airspeed reading and ground speed reading in the early part of the take off roll were significantly different, the outcome may have been different.
The 80 knot call has become so routine that complacency sets in. And the one time there is a serious discrepancy you can be assured of instant confusion. By the time both pilots discover there is a problem the aircraft is rapidly accelerating to V1. Remember the Boeing advice re rejected take off and that is above 80 knots only reject in case of fire or fire warning, engine failure, predictive windshear and if the aircraft is unsafe or unable to fly.
Checking the expected ground speed reading at the 80 knot call is an excellent safety measure. Easier than checking the standby ASI reading in fact. When in doubt with perceived airspeed differences during the take off run call above 80 knots, a check of the expected ground speed can resolve the differences and if necessary because things happen so quickly, consider falling back on the ground speed reading to plan the rotation. Might be a lot safer than a high speed abort and the ground speed indicator doesn't care if the runway is wet or dry.
A Boeing recommendation is the PNF (or should I say PM!) makes call-outs based upon instrument indications etc The PF should verify and acknowledge. If the PM does not make the required callout, the PF should make it. An incident to an A330 illustrates the point. Unknown to the captain as PM the captain's ASI under-read significantly because of an insect blocking the tube. The F/O was PF. During the take off roll the F/O noticed the captain had not made the 100 knot call. Assuming the captain had forgotten the PF continued the take off and was near VR when the captain called "100 knots". Sensing an airspeed problem the captain took control and rejected the take off at high speed. Hot brakes and tyre deflation due heat then occurred.
If when the PF was passing 100 knots and no call from the PM, the PF had called "110 knots my side" (allowing for acceleration), the ASI discrepancy would have been discovered much earlier. Better still, had the captain noticed his airspeed reading and ground speed reading in the early part of the take off roll were significantly different, the outcome may have been different.
...just to add RTO after V1 is for catastrophic failure when the ship is unflyable...so yes if you lose a wing or hit a fuel truck and burst into flames then I suppose you have no choice...either way it looks pretty bad
what if a meteorite hits you after V1 or the sky falls after V1...
what if a meteorite hits you after V1 or the sky falls after V1...
Reject past V1? Sure, I would rather go off the end at 50 knots than face the alternative of a loss of control in the air. Leaving half a wing in the side of another aircraft, flight control jam in a type that has no control split system, full reverser deploy? Who knows what the effect could be until it actually happens?
As most good ops manuals state, it is impossible to write a procedure for every eventuality. In such a situation the PIC is authorized to do whatever it takes. Some enlightened regulations say that, too.
As most good ops manuals state, it is impossible to write a procedure for every eventuality. In such a situation the PIC is authorized to do whatever it takes. Some enlightened regulations say that, too.
Join Date: Jul 2006
Location: 'tween posts
Posts: 197
Likes: 0
Received 0 Likes
on
0 Posts
take it as it comes
Its difficult to come up with a generic answer. its not a situation of one size fits all.the variables are: (and the list is not exhaustive)
1.type of A/c
2.TOW on the given day
3.Are you using V1 min?
4.RWY length/stop margin available
5.local knowledge of what lays beyond the RWY-may be a snow bank or a sheer drop
can Somebody add to the list.......?
1.type of A/c
2.TOW on the given day
3.Are you using V1 min?
4.RWY length/stop margin available
5.local knowledge of what lays beyond the RWY-may be a snow bank or a sheer drop
can Somebody add to the list.......?
Thread Starter
Join Date: Mar 2010
Location: NW
Posts: 269
Likes: 0
Received 0 Likes
on
0 Posts
So now that we have concurred that flying an un-flyable aircraft doesn't make sense....then it follows that a post V1 RTO, would be easier accomplished with the maximum available amount of runway in front of us.....
Ergo.. max power take offs, would burn up less runway to V1, meaning more runway for a post V1 RTO......vs... a reduced thrust take off....
So it would follow that the prudent pilot, trying to mitigate all risk from the flight, would embark to get to V1 as quickly as possible, using the minimum amount of runway, that in the event of a post V1 catastrophe, he has more runway to stop...
I would also suspect that if I hypothetically traveled up and down the runway at high speed....that I have a statistically higher chance of FOD, errant fuel trucks, aircraft taxing through intersections, other aircraft landing on me...it seems the least amount of time on the runway..reduces the risk of all these factors.....
So from a safety standpoint...wouldn't the safest option to be a max thrust take off vs reduced thrust take off?
Ergo.. max power take offs, would burn up less runway to V1, meaning more runway for a post V1 RTO......vs... a reduced thrust take off....
So it would follow that the prudent pilot, trying to mitigate all risk from the flight, would embark to get to V1 as quickly as possible, using the minimum amount of runway, that in the event of a post V1 catastrophe, he has more runway to stop...
I would also suspect that if I hypothetically traveled up and down the runway at high speed....that I have a statistically higher chance of FOD, errant fuel trucks, aircraft taxing through intersections, other aircraft landing on me...it seems the least amount of time on the runway..reduces the risk of all these factors.....
So from a safety standpoint...wouldn't the safest option to be a max thrust take off vs reduced thrust take off?
Ergo.. max power take offs, would burn up less runway to V1, meaning more runway for a post V1 RTO......vs... a reduced thrust take off....
and even if the rwy length were not limiting it may become limiting or excessive and dangerous, just a few knots from V1 and at a limiting V1...your stopping technique [ especially if there's no RTO autobrake/auto spoiler selection] must be test pilot perfect AT V1...and honestly whatever side you are on it takes lots of faith in the performance analysis...and from reading here the FAA leaves a lot to be desired in terms of both ASDA, TODA and flight path protection...It would be nice if everyone were as cautious as the performance experts who frequent this forum
RTOs after V1 should never become a 'routine' in lieu and such decisions are best reserved for dire catastrophe as described by others, there have been precedents of course were such a decision did save lives but it resulted from pilot error and it there was no choice it was luck and everyone knows that Hawkers a built very very tough
it seems you have improved your approach to us here...I hope
Join Date: Sep 2009
Location: Retired-ville
Posts: 402
Likes: 0
Received 0 Likes
on
0 Posts
So from a safety standpoint...wouldn't the safest option to be a max thrust take off vs reduced thrust take off?
The safest option would be to not commit the sin of aviation to start with.
Sure it's a pureist answer, but we all know aviation has many risks.
To eliminate all risk is clearly impossible, as much as to ignore all risk is a folly.
Therefore, one takes a suitable compromise between cost and risk.
Reduced thrust take-offs are one such area of compromise that has generally been found to pass the test of prudence by most pilots, although academics may question the logic.