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FlyingHonu001
Topic Author
Posts: 314
Joined: Thu Jan 30, 2020 2:33 pm

QY841 (EAT Leipzig A300-600F) rejected takeoff in Brussels

Sat Nov 28, 2020 11:42 am

Just curious: QY841 apparently aborted take-off after V1. If this was a passenger carrying aircraft, would this take-off be continued

https://www.airportia.com/news/eat-leip ... d-takeoff/
 
LimaFoxTango
Posts: 990
Joined: Wed Jun 16, 2004 11:33 pm

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 11:55 am

Passenger or cargo is irrelevant. If the crew believes the aircraft won't fly for any reason, they will reject the takeoff, even after V1.
You are said to be a good pilot when your take-off's equal your landings.
 
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Polot
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Joined: Thu Jul 28, 2011 3:01 pm

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 12:04 pm

Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.
 
SueD
Posts: 306
Joined: Sat Jul 27, 2019 11:35 am

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 12:47 pm

FlyingHonu001 wrote:
Just curious: QY841 apparently aborted take-off after V1. If this was a passenger carrying aircraft, would this take-off be continued

https://www.airportia.com/news/eat-leip ... d-takeoff/


Package cargo plane probably quite light load wise
 
Flow2706
Posts: 263
Joined: Sat Jan 28, 2017 7:20 pm

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 12:53 pm

Polot wrote:
Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.

Stopping above V1 does not necessarily mean that the aircraft won't be able to stop on the runway. This is only true for a balanced field takeoff. There are two criteria that have to be fulfilled at the calculated V1: If the takeoff is rejected at V1 the aircraft will stop on the runway (or stopway). The other criteria is that in the event of an engine failure at V1 the aircraft will be able to continue takeoff and fulfill performance requirements. On a long runway there is a range of speeds which fulfill both criteria. In this case the pilot or performance calculation software will chose a V1 speed in this range. If the takeoff is then rejected above the chosen V1 but still within the speed range the aircraft should be able to stop within the runway.
For this case, we can therefore not yet conclude if the takeoff was rejected before, at or after V1. However, I have read that the nose wheel had already lifted off when the RTO was initiated. If this report is correct it would indeed indicated the the takeoff was rejected after V1, as V1 is below Vr by definition.
 
VSMUT
Posts: 4894
Joined: Mon Aug 08, 2016 11:40 am

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 12:57 pm

Polot wrote:
Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.


The link OP put up doesn't say anything about the aircraft exceeding V1, however an aborted TO after V1 is certainly possible. As LFT wrote, if the aircraft is considered unflyable (or damaged enough that it won't make it back to the runway), you simply don't take off. In the case of cargo planes, we have seen some nasty incidents where fire in the cargo made the aircraft unflyable in so short a timespan that you won't make it back to land again. If I was flying a cargo plane out of an airport with a very long runway, knowing I was carrying a load of flammable whatever (batteries, chemicals or loads of other dangerous goods), I probably wouldn't be much for taking the problem into the air.

The circumstances were a bit different (aborted landing rather than takeoff), but the PIA A320 crash in Karachi demonstrates it pretty well. The aircraft was unflyable and going to crash.
 
ChrisKen
Posts: 1039
Joined: Tue Aug 05, 2008 11:15 pm

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 1:14 pm

Not sure where you've determined they were over V1 from, article states it was a high speed reject, which is technically anything above a few tens of knots. (in this case 150kts).

Even if they were past V1: As already stated, it's not mandatory to continue flight after v1. If the crew believe the aircraft is incapable of flight, they should reject the take off, pax/cargo/ferry.

Since the aircraft stopped within the confines of the available runway, one would suggest that the crew performed their remedial actions correctly.
 
bennett123
Posts: 10395
Joined: Sun Aug 15, 2004 12:49 am

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 1:30 pm

150 knots over ground

Is V1 determined by ground speed or air speed?.
 
TMccrury
Posts: 140
Joined: Sun Oct 09, 2005 10:24 am

Re: QY841 (EAT Leipzig A300-600F) rejected takeoff in Brussels

Sat Nov 28, 2020 1:57 pm

Part of the linked article mentions they nose wheel was already off the ground. This implies to me they were A) just past V1, B) Someone tried to rotate to early or C) they were at proper speed but something serious was going on with that aircraft and it was not going to fly.
 
kalvado
Posts: 2971
Joined: Wed Mar 01, 2006 4:29 am

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 2:08 pm

Flow2706 wrote:
Polot wrote:
Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.

Stopping above V1 does not necessarily mean that the aircraft won't be able to stop on the runway. This is only true for a balanced field takeoff. There are two criteria that have to be fulfilled at the calculated V1: If the takeoff is rejected at V1 the aircraft will stop on the runway (or stopway). The other criteria is that in the event of an engine failure at V1 the aircraft will be able to continue takeoff and fulfill performance requirements. On a long runway there is a range of speeds which fulfill both criteria. In this case the pilot or performance calculation software will chose a V1 speed in this range. If the takeoff is then rejected above the chosen V1 but still within the speed range the aircraft should be able to stop within the runway.
For this case, we can therefore not yet conclude if the takeoff was rejected before, at or after V1. However, I have read that the nose wheel had already lifted off when the RTO was initiated. If this report is correct it would indeed indicated the the takeoff was rejected after V1, as V1 is below Vr by definition.

Would maximum brakes energy also come into consideration at some point?
 
VMCA787
Posts: 130
Joined: Fri Sep 04, 2020 9:31 pm

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 2:18 pm

Polot wrote:
Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.


The issue is on twin-engine aircraft, you can't have a V1 greater than Vr. Not having flown the A300 series, I would imagine that was the case. If you do the calculation and have that situation, then Vr becomes the new V1 even though it is actually lower than the computed V1. Doing 2 engine ferry flights on the 727 with No. 2 inop, you would run into that case.
 
GalaxyFlyer
Posts: 6723
Joined: Fri Jan 01, 2016 4:44 am

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 2:32 pm

VMCA787 wrote:
Polot wrote:
Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.


The issue is on twin-engine aircraft, you can't have a V1 greater than Vr. Not having flown the A300 series, I would imagine that was the case. If you do the calculation and have that situation, then Vr becomes the new V1 even though it is actually lower than the computed V1. Doing 2 engine ferry flights on the 727 with No. 2 inop, you would run into that case.


I’d think in this case, it’s not V1 exceeding Vr, which, by definition cannot happen. It’s refusal speed or accelerate-stop speed that’s is faster than normal Vr for the weight due to lots of ASDA. Yes, the Vr for that weight can increase up to Vrefusal which is limited by brake energy. Refusal equals “accelerate-stop”.
 
Flow2706
Posts: 263
Joined: Sat Jan 28, 2017 7:20 pm

Re: QY841 Rejected takeoff after V1

Sat Nov 28, 2020 4:02 pm

kalvado wrote:
Flow2706 wrote:
Polot wrote:
Isn’t the fact that the plane stopped on the runway proof that it was not above V1 speed when decision was made to abort, and this is just a high speed RTO? V1 depends on factors such as a weight, you can’t just look at a speed a say oh that plane was above V1 because google tells you that’s the A300’s V1 speed. I’m not blaming you OP btw, I noticed some news articles commenting that it was above V1.

Stopping above V1 does not necessarily mean that the aircraft won't be able to stop on the runway. This is only true for a balanced field takeoff. There are two criteria that have to be fulfilled at the calculated V1: If the takeoff is rejected at V1 the aircraft will stop on the runway (or stopway). The other criteria is that in the event of an engine failure at V1 the aircraft will be able to continue takeoff and fulfill performance requirements. On a long runway there is a range of speeds which fulfill both criteria. In this case the pilot or performance calculation software will chose a V1 speed in this range. If the takeoff is then rejected above the chosen V1 but still within the speed range the aircraft should be able to stop within the runway.
For this case, we can therefore not yet conclude if the takeoff was rejected before, at or after V1. However, I have read that the nose wheel had already lifted off when the RTO was initiated. If this report is correct it would indeed indicated the the takeoff was rejected after V1, as V1 is below Vr by definition.

Would maximum brakes energy also come into consideration at some point?

Maximum brake energy could also be a consideration depending on the aircraft type and conditions. In theory Vr could also be limited by the maximum tire speed, but on most types this is not an issue. On the A320 I think I've never had a V1 limited by either maximum brake energy or by maximum tire speed, but I could imagine that it may be an issue on the A321LR/XLR at high weights.

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