Or this:

How often do catastrophic CG errors happen in airline ops?

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.

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.

Interesting that you thought of the same thing... The moment I saw the photos, I thought... "Oh boy, SSG was so desperate to prove his point"... perhaps with derate too... :ugh:

If this counts as abort after V1 :E
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..

Ummm...

Seems you demonstrated you hadn't yet reached V1max.

:ok:

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.

If gear up, second segment of climb, actually.

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.

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 :mad: dangerous. Half mass multiplied by the velocity squared can really bite you. And ground behind runway may have too low PCN for your ACN.

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:

• 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.

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

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!).

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.

welcome back ssg.
If the tires are blown you are not stopping so no numbers to run!!

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

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.

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.

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..

Hi SSG hows it going? ;)

Ssg reborn again indeed.

Most of us here fly real airplanes. Perhaps you should stick to your microsoft simulator world.

Well Guppy, I guess on your PC, after V1 the plane always flies..is that how it works on Microsoft Flight Sim?

Actually he's a 747 classic pilot, and yes they do always fly after v-1. We'll keep you posted if that changes.

:eek:

V1, or my job? :uhoh:

On my Proficiency Check...the airplane had better fly, or I'm out of a job.

SSG version X (I've lost count) continues to blabber on about how many have said "go" and crashed. He has yet to provide any numbers of:
% of a Go after a failure after V1, where they ended up with fatalities.
% of a a stop after failure after V1, where they ended up with fatalities.

Until then, I will not stop laughing everytime I see SSG or his derivatives online here.

PK-KAR

Thank you PK:ok:

That's the essence of the whole argument within this thread.

If you follow the SOPs you will save more passengers than if you don't.

If you are inclined to try and stop it ad-hoc, then please try this in a qualified sim and take the knuckle raps by the instructors pointer stick.

It's not even an arguement over which will save more passengers. One choice is right, one isn't. If one "saves" passengers by making the wrong choice, one is lucky; one hasn't actually saved anything. One has been saved from one's own foolishness.

Barring something that prevents the airplane from going airborne, there's no reason to reject at high speed, and as most all of us agree, it's with good reason. It's not a matter of playing the odds or leveling risk, or weighing where the most survivors will occur. It's a matter of making the correct choice, and in most all cases, that's going airborne.

I looked at some numbers today and would like explenation if possible
please.

In the performance A320 book I picked a sea level runway with zero slope,
3800 meters length and checked the Take off speeds

115/ 119/ 122 Are the V1,VR, V2 flex 68 for 54000 kg take off weight.
149/ 149/ 152 flex 68 are the speeds for 63000 kg take off weight.

Now If I abort at 116 V1 for the 54000 kg weight, the plane will over
run the runway? but if I abort at 148 speed and weight 63000 kgs
The plane will stop before the end of the runway, although I would have
used more runway in the second case as the flex is the same.

This really does not make sense, as I had less speed, less weight
and more runway for the 54000 kg take off.

Any explanation please.

tarik123
 

Whilst this thread has been concentrated on safe stopping, what those V1 figures actually mean are:

At 54000kg at 115Kt the aircraft will accelerate and take off in the remaining runway even if you lose an engine.

At 63000kg you need to be at 149Kt for that to be true.

My Question is very simple speed 115, less weight and more runway ahead
is more critical than 144 speed more weight and less runway, this really
does not make sense.

Really :confused:

Any graphics available to make sense out of this?

tarik123
 

And the answer is equally simple as I stated above.

There is a fundamental difference between "good-to-go minus one engine" and "committed to take off".

Strictly speaking V1 is the first one. However as the aircraft weight goes up or the runway length comes down the two parameters converge.

Yes, at 54000kg and 116Kt you may have the luxury of a second or three to decide whether your problem was really so bad that the aircraft wont fly and still stop with runway to spare. At 63000kg and 149kt you almost certainly would not.

It is the deadly grey area inbetween that has been exercising the contributors to this thread.

who cares about stats...
 

I would not care what the statistics and the number says..
I would go by the SOP rather than creating new definition of V1 at the most critical time of my life...
Personally, my strategy is : as I sense entering the high speed area (>100kts), I keep telling my self " This would be a 'go' "
by the way, does anyone know how many times the engines of airliners have failed above 100kts or closer to actual V1...

cheers

Ifly Indigo
 

How many times engine failure after V1? If I read you right, what difference does it make? You don't like stats. "What would I have gotten for Christmas if I had gotten something more?"

Airfoil

it was rhetoric..
 

Yes, I don't like to give blind importance to stats and I am not going to abort close to V1.. I just wanted to draw attention of the readers to the point that rarely engines fail close to V1 (excluding possibility of bird strike)..


cheers

The issue is not SOP or what whoever will do, it is about available
distance to stop if an abort takes place at speed that is above V1
AT 54000 KG??

IF AT 64000 KG , LESS RUNWAY AND 30 KTS MORE SPEED AND STILL
ON PAPER THEIR IS ENOUGH RUNWAY TO STOP THEN at 54000kg
I should be able also to stop at 149 kts safely.

Tarik,

You did specify flex thrust, right?

Tarik,(ssg)
Whenever you are not at the runway limited max take off weight there will be a range of v1 speeds available.

Think of the lowest v1 as the lowest speed you could safely continue the take off after an engine failure and the highest v1 as the highest speed from which you can stop.

Some one decides on a policy of which speed to use and you use it. It may be that the decision is to use "Balanced" speeds in which case if the engine failure occurs at the exact Vef speed used in the calculation then the distance to continue to screen height would be the same as the distance taken to stop.

For all other v1s the distances required are unequal.

Your question about different speeds at different weights makes no sense! Now if you were to ask why can't i stop after a V1min of 119 when the V1max at the same weight is 150 then that would make for an interesting discussion.

as it is you need to study the concept a little more then get back to us.

Our company uses the flex+derate for Take-Off where possible. However I am interested as to whether there any any operators who use some sort of software package which would give you all 3 V1's in preflight calculations for some kind of situational awareness.

For instance you are light as in Tarik's example with a low V1 go, but your company gives a balanced field V1 slightly higher. Is there anywhere you could obtain a high V1 stop for the same take-off criteria.

I ask as lets say for instance you get to the V1 low, and soon after get some kind of manfunction (jammed controls, etc...), if you knew what the higher V1 was, lets say the 149 as from the previous example - you might be in a postion to consider the option of relanding/or aborting if still on the ground and not at Vr if say your speed was not at V1 high.

Not sure if such a scenario is accurate or even desirable as it would add a grey area to the idea of V1 being a stop/go concept but I thought I'd ask.

My 2 pfennig:

Look at the charts (table?) for the highest TOGW under the existing conditions (assuming full power, no derates/flex which would change everything) and use that V1 as the V1max. It is a rough approxiamation, but the real answer is to get out the charts, probably unavailable to most of us, and compute all the numbers for the TODA, TORA, and ASDA. Compute Vmcg, Vcefs, Vrefusal, accelerate-go, etc. A 20 minute process, if you have the charts and not very useful in an airline environment.

GF