Would you abort after V1?
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
...if the plane didn't accelerate to VR, massive control failure..missle hit the wing...anything that I knew would keep the plane from flying up in the air...
How often do catastrophic CG errors happen in airline ops?
Join Date: Mar 2001
Location: I wouldn't know.
Posts: 4,498
Likes: 0
Received 0 Likes
on
0 Posts
Damn, they never even tried to calculate their CG? That is something that will never happen in airline ops. However, miscalculated CGs do happen, very rarely though. The Lufthansa 737 QC comes to mind where they loaded several tons of freight in supposedly empty containers putting the CG way out of the forward limit, still the thing flew, although they had to use stabtrim to fly it.
A real concern however is the use of generalized standard weights that are most probably too low.
A real concern however is the use of generalized standard weights that are most probably too low.
Join Date: May 2008
Location: Mexico
Age: 81
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Emory flight out of Sacramento....cargo bins shifted..unflyable aircraft...I would imagine they shifted at rotation though, so the crew couldn't have caught it.There are million reasons why a plane won't fly, before or after V1, we have to be ready for it.
Join Date: Nov 2001
Location: Somewhere in the Tropics UTC+7 to 9
Posts: 450
Likes: 0
Received 0 Likes
on
0 Posts
Maybe ssg was flying the B747 and attempted to abort after V1. Very sorry, could not resist.
If this counts as abort after V1 
I have experienced aborted takeoff in L410 just after PNF selected gear up when the left engine lost power and autofeathering failed. I was PF and perhaps one second later cpt and I decided to retard power, consequently regaining control and landing straight ahead - everything worked out ok. Luckily the runway was long enough for three greens to light up again.
Couldn't sleep for a few days (flights were from 10pm to 6am) after that..
I have experienced aborted takeoff in L410 just after PNF selected gear up when the left engine lost power and autofeathering failed. I was PF and perhaps one second later cpt and I decided to retard power, consequently regaining control and landing straight ahead - everything worked out ok. Luckily the runway was long enough for three greens to light up again.
Couldn't sleep for a few days (flights were from 10pm to 6am) after that..
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes
on
0 Posts
What Dufo did was NOT an aborted take off. He did a forced landing straight ahead.
The take off was well and truly over if his gear was up, in-fact so was the first segment of the take off climb.
Back to school for you ssg.
The take off was well and truly over if his gear was up, in-fact so was the first segment of the take off climb.
Back to school for you ssg.
Barit1, if the runway is long enough and the aircraft is a STOL or nearly STOL type, or even a high performance type operating at a light weight 'V1 Max' for the situation described could be any speed that allowed it to stop by the far end. But then, in the interest of handling, tyre speeds etc Vr would happen before your 'V1 Max', so that opens up another can of worms and one which has never been addressed by certification.
My belief, of course, is that if it won't fly, I hope I recognise the fact in time to chuck it back on the ground. If it will fly, I will respect V1. It's the grey area between knowing and not knowing whether it will fly that is the problem. If seriously in doubt, on the ground is the better place to be, as long as you are not going to hit a bridge or brick wall or block of apartments on the over-run. Had the Concorde crew known what was unfolding, I bet they would have rejected even though they had passed V1. Sadly, they had no way of knowing just how bad it was.
My belief, of course, is that if it won't fly, I hope I recognise the fact in time to chuck it back on the ground. If it will fly, I will respect V1. It's the grey area between knowing and not knowing whether it will fly that is the problem. If seriously in doubt, on the ground is the better place to be, as long as you are not going to hit a bridge or brick wall or block of apartments on the over-run. Had the Concorde crew known what was unfolding, I bet they would have rejected even though they had passed V1. Sadly, they had no way of knowing just how bad it was.
Buffo was flying the turbolet. Turbolet is Czech-built, high-wing, STOL, unpresurrized twin turboprop. It can be flown at MTOW from 800m grass strip. Ljubljana has 3000m of asphalt runway. Not quite a limiting runway, eh? What if it were ATR flying from 1200m rwy? Hitting the cornfields at 100kt is not particularly survivable.
If you abort above V1 in runway limited situation, rule of the thumb is that speed off the end of the runway is speed above V1 when the abort is initiated multiplied by 10 (source: DLH FCM, chapt 7). And that is with proper abort technique (full spoilers, full brakes and idle thrust). Therefore abort at mere 5 kts above V1 gives you 50 kts as you crush the red lights.
So would I abort about V1 in a transport category airplane? If I have a choice - no. Not just because my SOP tells me so but because it is waaay too
dangerous. Half mass multiplied by the velocity squared can really bite you. And ground behind runway may have too low PCN for your ACN.
If you abort above V1 in runway limited situation, rule of the thumb is that speed off the end of the runway is speed above V1 when the abort is initiated multiplied by 10 (source: DLH FCM, chapt 7). And that is with proper abort technique (full spoilers, full brakes and idle thrust). Therefore abort at mere 5 kts above V1 gives you 50 kts as you crush the red lights.
So would I abort about V1 in a transport category airplane? If I have a choice - no. Not just because my SOP tells me so but because it is waaay too
dangerous. Half mass multiplied by the velocity squared can really bite you. And ground behind runway may have too low PCN for your ACN.
Join Date: Sep 2002
Location: La Belle Province
Posts: 2,179
Likes: 0
Received 0 Likes
on
0 Posts
Just to add to clandestino's post (that "times ten" rule is one I've not seen before, but sounds useful .. must check for our types ..)
A typical rule of thumb used for assessing safety implications of runway excursions goes something like:
Now, there are of course exceptions (good and bad luck) but it's a decent average.
A typical rule of thumb used for assessing safety implications of runway excursions goes something like:
- 40kts and below : "major" - damage and injuries, no deaths
- 40 to 70 knots : "hazardous" - serious damage, risk of death
- 70 plus : "catastrophic" - hull loss, multiple deaths
Now, there are of course exceptions (good and bad luck) but it's a decent average.
Join Date: Dec 2007
Location: I know EXACTLY where I am..
Age: 54
Posts: 97
Likes: 0
Received 0 Likes
on
0 Posts
Clandestino
never heard of the times 10 rule before either. Sounds like a good rule of thumb, though. I think ill do some maths, and see if I can get to similar numbers. (better than verifying by experiment).
MadFltScientist - true, but only as long as the area beyond the runway isn't littered with walls, berms, ditches and whatnot. There are still too few airports out there which have a safety area to allow you to stop gently after an overrun.
Regards, OORW
MadFltScientist - true, but only as long as the area beyond the runway isn't littered with walls, berms, ditches and whatnot. There are still too few airports out there which have a safety area to allow you to stop gently after an overrun.
Regards, OORW
Last edited by OutOfRunWay; 29th May 2008 at 08:39. Reason: lousy punctuation
Some good numbers above to think about. Has any research been done in to what sort of maximum speeds are practical for deliberately inducing a ground-loop or going in to soft grass or earth? Thinking - that if you see an over-run is inevitable and to continue straight off the end would be really, really ugly, what is there to lose by putting it off the SIDE of the runway at an angle dependant upon what obstructions are in the side area? I have seen it done successfully on wet grass during a landing that was about to over-run, but granted it was a DC3 and only doing about 25 knots when the guy gave it a bootful of rudder and a well-judged squirt of throttle. He actually got it nearly all the way around through 180 degrees, chewing up a couple of cone markers as he went but basically keeping it within the runway confines. On another occasion I saw another DC3 deviate at a near right-angle off the tarmac onto grass, but that one was a crosswind landing stuff-up by a deputy chief pilot who was out of his depth on the old Gooney. Neither incident caused any damage other than skid marks (of both the visible and not so obvious kind!).
Join Date: Sep 2002
Location: La Belle Province
Posts: 2,179
Likes: 0
Received 0 Likes
on
0 Posts
Did some quick maths with some simplistic assumptions about accels and decels and that "rule of ten" is pretty good. It actually looks like it UNDERESTIMATES the runway exit speed for small values - it looks about right for 5-6 knots, for reasonable V1 values. For one or two knots, the multiple is more like 20, though. And for ten or more knots delay the factor drops to 7 or lower.
If I use the 40/70 break points for hazards, then any delay of more than, say, 4 knots is hazardous, and anything over 9 or 10 knots is catastrophic. And, as OORW astutely notes, that's assuming a relatively "friendly" overrun area...
Assuming a (lowish) takeoff T/W of, say, 0.25'g', that's an accel of about 5knots/sec. A light weight could see that nearly double. So those speed increases equate to about a second of delay.
If I use the 40/70 break points for hazards, then any delay of more than, say, 4 knots is hazardous, and anything over 9 or 10 knots is catastrophic. And, as OORW astutely notes, that's assuming a relatively "friendly" overrun area...
Assuming a (lowish) takeoff T/W of, say, 0.25'g', that's an accel of about 5knots/sec. A light weight could see that nearly double. So those speed increases equate to about a second of delay.
Join Date: Jun 2008
Location: Hawaii
Age: 58
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
thebooms
I grew up in props and we always planned on V1 max and in most cases V1=Vr. It certainly was easier to abort a prop plane over a jet. Much more controllability on the runway and easy to abort. It was a big learning curve making the transition to jets and taking them airborne at V1 is the way to go. Our FMS has a V1 max function but our SOP calls for balanced field or V1 min. Ask to try a V1 max in the sim and I think you'll find that flying is the way to go. Good luck
Join Date: Jan 2004
Location: spain
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
Go After V1
Iwill tell you a story that happened with me long time ago,
It was L1011/500 250 pax on board, take off weight was around
200000 kgs, 400000 lbs , just after V1 we heard a loud bang, we
continued rotation. just after leaving the ground a black thing
just flew infront of the winshield and went straight into engine
no2, at that time sever vibration shook the plane, F/E started
screaming Vibration on eng 2, tower also reported lots of smoke
from our plane, eng 2 throttle was moved back to idle and
vibration stopped, at that time the lead cabin crew flew to the
cokpit reporting smoke from the left engine, we looked at engine
no1 parameters, and it had the high EGT light on, limitation
was 800 c for max 20sec, now we thought that F/E made a mistake
reporting eng2 instead of eng no 1, as we learned in the sim that
sever damage is always accompanied by high temp, so eng no 1
was retarded below temp limit and eng n02 thottle was addvanced
slightly, which brought vib back, we realised that 2 engines were affected,
it took us 10 min to reach 1000t AGL, luckily no high terrain around,
Engine no 2 was shut down, and no1 was kept below High EGT limit.
We started dumping fuel and the tower reported lots of rubber
on the runway, which meant one tire was lost. fuel was dumped
to the minimum which took almost one hour, we dropped the
landing gear and made a low pass over the tower, which reported
a left tire was gone.
We landed on the right side first, did not use left reverser and stopped
the plane on the runway,no evacuation was made as there was no fire
reported.
The main tire blow up at V1, hit the left wing and ruptured the fuel
tank in front of eng 1 and went straight in front of the windshield
into eng no 2.
It is always safer to go airborne, deal with the problem, and come back
and land.
It was L1011/500 250 pax on board, take off weight was around
200000 kgs, 400000 lbs , just after V1 we heard a loud bang, we
continued rotation. just after leaving the ground a black thing
just flew infront of the winshield and went straight into engine
no2, at that time sever vibration shook the plane, F/E started
screaming Vibration on eng 2, tower also reported lots of smoke
from our plane, eng 2 throttle was moved back to idle and
vibration stopped, at that time the lead cabin crew flew to the
cokpit reporting smoke from the left engine, we looked at engine
no1 parameters, and it had the high EGT light on, limitation
was 800 c for max 20sec, now we thought that F/E made a mistake
reporting eng2 instead of eng no 1, as we learned in the sim that
sever damage is always accompanied by high temp, so eng no 1
was retarded below temp limit and eng n02 thottle was addvanced
slightly, which brought vib back, we realised that 2 engines were affected,
it took us 10 min to reach 1000t AGL, luckily no high terrain around,
Engine no 2 was shut down, and no1 was kept below High EGT limit.
We started dumping fuel and the tower reported lots of rubber
on the runway, which meant one tire was lost. fuel was dumped
to the minimum which took almost one hour, we dropped the
landing gear and made a low pass over the tower, which reported
a left tire was gone.
We landed on the right side first, did not use left reverser and stopped
the plane on the runway,no evacuation was made as there was no fire
reported.
The main tire blow up at V1, hit the left wing and ruptured the fuel
tank in front of eng 1 and went straight in front of the windshield
into eng no 2.
It is always safer to go airborne, deal with the problem, and come back
and land.
Join Date: Apr 2005
Location: Australia
Posts: 1,414
Likes: 0
Received 0 Likes
on
0 Posts
A thoroughly interesting set of replies and certainly thought provoking. From reading countless incident and accident reports of over-runs over many years it has been my personal view only that from 15 knots below V1 it is safer to continue the take off if on a limiting runway length wet or dry surface. I know this would horrify the experts but it is a question of learning from the experience of others. Fortunately I have never had to put this to practice except in the simulator.
Join Date: Jun 2008
Location: Centerville
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
That's crazy...a canned 'let's go' regardless of the circumstances..I wonder how many airliners tried to fly it off, only to crash somewhere down the road vs even the very worst of overruns where everyone walked away.Sorry guys, sometimes the plane doesn't want to fly, and I could sit here and come up with failure after failure in the sim, where flying it off, is a death sentence for you and the passengers.I think some of you need to get out of your airline sims and go to another sim facility: When you get there say 'sock it to me' then you will see what I am talking about. Smart pilots recognize if they have a flying aircraft or not, and don't just default to SOPS, checklists and canned responses to all scenarios..
