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Rejecting A Takeoff After V1…why Does It (still) Happen?
Aborts at a high speed (above V1) are rare. However when they occur the outcome can be a serious accident. The following paper discusses why this still occurs despite efforts from the industry to stop this.
http://www.nlr-atsi.nl/eCache/ATS/15/694.pdf The analysis in the paper showed that there is still plenty of room to improve takeoff safety and reduce the number of unwarranted rejected takeoffs above V1. What do pilots and safety specialists think about this? All views are welcome but please read the paper first:)! |
I believe there has to be more emphasis during simulator training, to help understand the "unsafe to fly" condition. Simulator training these days concentrate mainly on RTO's due to engine failures/fires. Of course, there is only so much that the simulator can simulate. Nice article by the way!
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You are correct. Pilot simulator training often presents RTOs as engine-related events while the Takeoff Safety Training Aid (1993!) gives recommendations about other failure conditions to consider. The majority of all RTO accidents were not related to engine problems. In these cases it is possible that the pilots were not fully prepared to recognise cues of other anomalies during takeoff. Pilots often interpret these other anomalies (like a tire burst) as events that threaten the safety of flight and decide to reject the takeoff at any speed. Indeed it is not easy to put these other than engine failure anomalies in the simulator.
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Practical reality suggests that at V1 there is neither time nor sufficient remaining pavement to intelligently decide whether the airplane will fly or not.
So there is nothing to think about, but only to remove your paw from the thrust levers/throttles by V1 and to keep your paw off the thrust levers/throttles. :ooh: |
Have long since retired; but during the 50 plus years of flying experience which included the careful study of accident reports and countless papers on the dangers of high speed aborts, I have always conditioned my thinking to continuing the take off from 15 knots below V1 unless I was absolutely certain the aircraft would not fly.
One could speculate on how to define how you would know for certain if the aircraft would not fly. It all gets too hard. While the 15 knots below V1 figure was always in my mind it was a personal private choice and I never told the first officer. My point being to avoid a legal or company SOP argument recorded on the CVR. There have been many instances of fatal overuns caused by stuffed up aborts near V1 but very few of clipping an obstacle in the take off splay in the go situation. |
However there is at least one case when a T/O rejection above V1 maybe saved lifes. About 10 years ago or so, an Air Liberté MD83 stroke a Shorts 330 at Roissy CDG, France. Basically the MD was performing its T/O roll after having had his T/O clearance when ATC did a tremendous mistake, allowing a Shorts 330 to line up from a mid position taxiway on that same runway. Nightly operation. Visibility less than average. Language misunderstanding (french language ATC <-> MD83 vs english language ATC <-> Shorts). The MD's left wingtip stroke the Short's cockpit, instantly killing the unfortunate F/O. Although the MD was a few knots above V1 its crew chose to abort their T/O and I think they took the fair decision as 1/3 to 1/2 of their left hand wing was torn off. And as they were light on a pretty long runway they managed to come to a full stop before the runway end.
Had they chosen to continue their T/O, none would have been able to say the airplane would have flown safely. H. |
Final report on the high speed RTO overrun with a PSA Airlines CRJ2
The final report on the high speed RTO overrun with a PSA Airlines CRJ2 at Charleston on Jan 19th 2010, has been released: DCA10IA022
From the report: The Capt. stated that he did not think the first officer had called out V1 before he initiated the RTO. The F/O stated that he thought that the RTO was initiated before reaching V1 and that he knew that an RTO should not occur after reaching V1. NTSB Report: “The captain initiated a rejected takeoff (RTO) about 5 seconds after he started moving the flaps and when the airplane was at an airspeed of about 140 knots, which was 13 knots above V1.” |
Then there was the TWA L1011 at KJFK (13R) that "aborted" just after liftoff. That was a totally asinine decision. The runway length and the benign overrun area (at least that day) saved their bacon in spite of themselves. It destroyed the aircraft, though.
I was astounded that both TWA management and the FAA supported this utterly insane act by the captain. The NTSB, though, saw it through untinted glasses, if I recall correctly. |
attn Glue Ball
I operate a Gulfstream, and need a few thousand feet.
I operate from 12,000 ft of paved surface, I could do a touch and go, and still have room to spare. Horses for courses..... glf |
Aterpster. I think you are referring to the following case:
IMMEDIATELY AFTER LIFTOFF THE STICK SHAKER ACTIVATED, AND THE FIRST OFFICER, WHO WAS MAKING THE TAKEOFF, SAID 'YOU GOT IT.' THE CAPTAIN TOOK CONTROL, CLOSED THE THRUST LEVERS, AND LANDED. HE APPLIED FULL REVERSE THRUST AND MAXIMUM BRAKING, AND TURNED THE AIRPLANE OFF THE RUNWAY TO AVOID A BARRIER AT THE END. A SYSTEM DESIGN DEFICIENCY PERMITTED A MALFUNCTIONING AOA SENSOR TO CAUSE A FALSE STALL WARNING. THE SENSOR HAD EXPERIENCED 9 PREVIOUS MALFUNCTIONS, AND WAS INSPECTED AND RETURNED TO SERVICE WITHOUT A DETERMINATION ON THE REASON FOR THE INTERMITTENT MALFUNCTION. THE FIRST OFFICER HAD INCORRECTLY PERCEIVED THAT THE AIRPLANE WAS STALLING AND GAVE CONTROL TO THE CAPTAIN WITHOUT PROPER COORDINATION OF THE TRANSFER OF CONTROL. NTSB REPORT AAR-93/04 I don’t think it is a true RTO as the aircraft already left the runway. Still it is interesting to notice the reaction of the co-pilot on the stall warning in the light of many (also recent) occurrences involving inappropriate reaction to stalls. |
decurion:
I don’t think it is a true RTO as the aircraft already left the runway. The NTSB title of its investigation report is: Aborted Takeoff Shortly After Liftoff Finding Number 12 of the report: 12. The captain made a "split second" decision to reject the takeoff by reducing the engine thrust. His decision was very likely based, in part, on the perception of available runway to stop the airplane. |
aterpster, I think you are right. Interesting case by the way.
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homebuilt
Good post. I remember that the Air Liberte sat near the end of 27L for a year or so, the Shorts was eventually broken up there. 27L is a looooong runway. Why not stop, if you need to? Remember the 748 that stopped well after V1 at (I think) East Mids? Capt was congratulated, publically at least. :suspect: |
Originally Posted by BBF
Remember the 748 that stopped well after V1 at (I think) East Mids?
Capt was congratulated, publically at least and professionally. |
BBf, BOAC; Re HS748 Stanstead.
Read the AAIB report carefully, re decisions and actions (3/2001 (EW/C98/03/7)). With hindsight, the decision was ‘incorrect’ (yet all decisions at the time are correct from the perspective of the decision maker), however the resultant fire from which a correct decision might be concluded, was perhaps exacerbated by other ‘erroneous behaviors’ in procedure. Learning points from this accident are the power of startling or extreme graphic events to bias decision making, and that on balance a Go-Minded attitude (with correct engine shut down procedure) should provided a similar or higher level of safety than a decision to land straight ahead on a long runway. In similar circumstances – a surprising event with a long runway ahead – another Captain related that he did not believe that the cues (noise and vibration from a thrown tyre tread) could be generated by a normal aircraft – hence the decision to a land ahead – surprise and incomprehension. However, on a shorter runway the takeoff would have been continued, but no reasoning for the change could be offered. This indicates the complexity of the decision making process, highly dependent on the perception of the situation in a time pressured environment, and bias – our predispositions towards particular actions (knowledge and understanding of risk – see the Training Aid). I doubt that extensive simulator training would ever cover the range of scenarios, nor generate the requisite surprise; thus it might be more effective to practice the drills associated with stop or go in relation to V1, and as the Training Aid suggests, be Go minded – education and knowledge to dispel inappropriate bias. In addition, from the report (#1), keep the decision choice to a simple ‘if – then’ option, which entails considering the reality and probability of operational scenarios – keep the SOPs practical. Human judgment should still the best solution in ‘unforeseeable’ circumstances, and although we are ‘ground dwellers’, flying – like the birds – offers another dimension for safety, as well as more time (and longer runways) for the subsequent choice of action. |
I don't want to drag out an old accident here, sp, but my copy tells me that the action to re-land was considered 'sensible in the circumstances' by AAIB and I recall the Captain telling me that it had been suggested to him unofficially that the wing may well have burnt through during the positioning to land after continuing. I judge the decision a good one.
It is, after all, what we are paid to do as Captains - to take decisions at the time for which we stand responsible and sometimes 'normal' rules need to be abandoned. 'Never say never'? |
BOAC, re HS 748 accident, which the AAIB investigated and reported circumspectly – avoiding ‘error’ and blame.
I don’t have a problem with the Captains decision in the particular situation, but what about a shorter runway etc, etc. Nor do I have a problem with discarding standard procedures in ‘non standard’ conditions. The HS748 accident suggests that the cues invoking surprise might not have been considered or realized in training – and perhaps not even possible for any aircraft type. These are the areas that require improved RTO training. The Training Aid provides a range of situations and considerations but perhaps fails to provide adequate guidance on probabilities of occurrence and human behavior aspects. The introduction/use of ‘if unsafe or unable to fly’ IMHO is detrimental to safety. GlueBall touched on this (#4); it is unlikely that sufficiently reliable cues or time will be available for a decision. Environmental issues, i.e windshear, might be judged a failure in the decision to commence the take off, if so then we need to improve awareness and risk assessment. Similarly a truck or even an elephant on the runway (I’ve experienced one of those) is a real but low probability event, but again aspects which might be determined before V1 thus avoiding the possibility of rejecting ‘above V1’. The report (#1) appears to identify problems with pilot’s inability/reluctance to change the decision/action process at V1. Perhaps because of poor speed awareness, or where correctly deciding to reject before V1, slow actions or incorrect technique result in an overrun; again, these are basic training issues. However, IMHO the dominant issue is dealing with surprise – shock, even fear, an aspect which can be in most abnormal / emergency situations. Thus, how do we train pilots to manage surprise? |
"...decision was very likely based, in part, on the perception of available runway to stop the airplane." |
There is a tremendous amount of outcome bias in this thread.
What's a good decision by a captain? One that saved lives. What's a bad decision by a captain? One that cost lives. The rightness or a wrongness of a decision in the minds of too many people is simply a function of the results that followed from it. But hindsight is always 20-20. That has absolutely nothing to do with safety as a process. The key question is does any improvement in procedures or training make a difference in safety outcomes when the outcome of the relevant decision making is unpredictable in advance. Faced with a whole host of unknown factors successful outcomes often don't come down to training or procedures but old fashioned luck. Honest captains admit this. Not that here are many honest people around, captains or no. :sad: |
Originally Posted by sp
I don’t have a problem with the Captains decision in the particular situation, but what about a shorter runway etc,
SP - mountainbear has summed it up neatly in his para 2. If we are to talk forensic 'what-ifs' years after ('shorter runway etc'), 'whatif' the wing had fallen off downwind, having had 3000 ft or so of tarmac to land on? As I said in my previous last para - when the chips are down you make the decision and mountainbear's para then analyses it. Short of 'training' by popping a large paper bag behind PF in the sim, that sort of 'surprise' is what the human brain copes with, either successfully or not. (Interesting to see a scientist write the software for that decision.) Losing 2 motors on a heavy 74 out of Brussels and stopping at or above V1 brings the probably inevitable crash scene inside the airfield boundary - right or wrong? I do not wish to judge. |
V1 is a threshold where below this you have better chances to survive when you abort, above this you have better chances to survive when you continue. it is not a guarantee that all will be nice when you continue above v1. when e.g you have an all engines fail , wing seperation etc. you need not do discuss the V1 - but when this happens there is no procedure anymore that gives you a chance to handle this situation, you may simply crash and burn.
we have situations where the pilots ( e.g concorde crash) did all right regarding V1 and the outcome was killing all the people. nevertheless- there is no time to think about this on takeoff roll and in the vast majorities of failures continueing above v1 gives you a better chance to make it. |
Short of 'training' by popping a large paper bag behind PF in the sim At the subsequent Court of Inquiry (aka the de-briefing) he said he thought the loud crashing noise was a simultaneous severe damage loss of both engines and that in his professional opinion the 737 doesn't fly too well with no engines so he put it back down real quick and survived to tell the tale. |
nevertheless- there is no time to think about this on takeoff roll and in the vast majorities of failures continueing above v1 gives you a better chance to make it. Once we put a human being inside the cockpit everyone has to accept that "to error is human". I'd go one step further than BOAC: Not only do I not wish to judge, I think it's unfair to judge. It strikes me as a grand game of "gotcha!" were the only major difference between the person who is found out and the person who is not is luck. In saying that I don't want to suggest that luck is always the determining factor. Sometimes there is clearly a deficiency/superiority in skill or training. But according to the article in the OP a long-haul captain expereinces such an incident once every 25 years. If we as as a community are unwilling to accept that when faced with a once-in-a-career event the very human pilot gets it wrong then lets stop all the hand-wringing and let the computer do it. At least you won't have the captain to kick around any more on that score. |
"...decision was very likely based, in part, on the perception of available runway to stop the airplane." If I understand, that means that if I reject my T/O above V1 on a balanced runway I'll get out the runway but my wheelbrakes will be working as long as I didn't reject my T/O at a speed higher than Vmbe. Just my two cents.:ok: |
I agree with Johns view
My take off run is in the order of 2,500ft, and the runwal length is 12,000 ft, my V1, can be in the order of 1,000ft.
In earlier types flown V1/VR was within 1 second of each other, but currently now about 5 seconds.....and still 10,000 ft of runway ahead. I was taught that the fire department do not have ladders high enough to reach you in the circuit, but can drive fast enough to catch you on the ground. Horses for courses. I was interviewed for a corporate job in India, a few years back, and was asked by CO flying of the company in question, would I ever STOP after V1...I gave the above explanation. he was not happy.A few years later he crashed and burned, perhpas because he followed the check list. The check list is the best know solution for some but not all problems. The definition of V1, is DECISION SPEED etc, etc, not GO speed. glf |
John,
Lack of basics is a killer isnt it?:E Doesnt your specific aircraft type have VSTOP and VGO speeds rather than a single V1 speed more pertinent to airliners types? I dont believe your on the spot assessment of excess runway available in case of lets say blown tires is the way forward to a sound decision,especially with your seemingly over confidence of your aircraft performance. For your info,on my type,reduced thrust(assumed temp) is safer for both STOP and GO decision,so overrun events have none to do with these incidents.. |
De Facto - You can either hire pilots that can look out the window, decide how much ice is on the wings...or simply hit the boots when the ice light comes on..
You can have all your pilots nick a fuel truck, and fly a broken wing off the ground, killing everyone right after V1, or you can hire a pilot who recognizes he's got an unflyable plane.. If your going to make the argument that all decisions/scenarios are in the checklist I can sit here and give you writer's cramp to the contrary... Either way, you won't be convinced, because in the end, you need guys that take orders and get along..... so a few planes crashing once in a while flown by 200 hour pilots is still cheaper then packing the cockpits with 10000 hour captains who tend not to screw up.... |
The definition of V1, is DECISION SPEED V 1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance. To interpret, the decision has to be made prior to V1. |
The point is moot....just because a plane will accelerate to V1, does not mean you have a plane that will fly after VR...
The pilot needs to do more then just push the throttles forward and look at the airspeed indicator for all his answers.... |
John's earlier point about what V1 actually means on some aircraft is quite valid. It does not mean V1 for a balanced field. Under some certifications you get take off field length (TOFL) which is the min runway required. It also has a V1 for that length. If you are taking off from a space shuttle diversion its still the same speed. In that case there may be good reasons to stop after V1. Unfortunately you don't have any data to go on but if you have enough length for TOFL plus landing distance required there is a better than average chance you can stop.
What about cases such as a flock of birds getting airborne and crossing the runway just as you are about to rotate. If you abort the plane is fine is you go you give yourself multiple bird strikes. Just like everything else in the manual you have to take the information and apply it to your circumstance. |
Greendeck,
You are talking about balanced field v1,which is correct as you will have runway remaining if you stop AT V1 or maybe after( if you are not at the runway length limit weight in the first place or if you are not in a improved climb scenario). John doesnt seem to have any knowledge of reduced thrust performance due to the aircraft he's flying or because of his company OPs or just lack of knowledge. However,55% of overruns are due to reject after V1 speed...(and for reasons other than serious problems).80% not engine related. Your flock of birds surely is NOT a strong enough reason to initiate a highspeed RTO...why not delay your rotation?rather than guestimating your stopping distance? What will you tell your CAA, when you are facing them?i rejected and wrecked a multimillion dollars aircraft,possibly killing many onboard because you thought that the birds MAY be ingested and fail both your engines? But there again,pilot decision. Now because I am soooo nice and looked into my files,here is a link to your local US FAA,hopefully people will read again:E http://www.faa.gov/other_visit/aviat...off_safety.pdf |
Boeing presentation on V1
This presentation by Boeing could be interesting regarding the discussion of V1
http://www.captainpilot.com/files/BO...%20of%20V1.pdf |
Following our look at the 748 at Stansted which did abort when airborne, a friend has sent me details of a sad fatal accident to another 748 with a similar RR Dart disintintegration which DID continue and subsequently crashed killing all on board.
The Transportation Safety Board of Canada report number H90001, Quebec Air F27B Rolls Royce Dart engines, CF-QBL Flight No 255 QuebecCityAirport, 29 March 1979 The flight lasted 1min 12secs after lift off. Fourteen passengers and three crew died in the crash. "At time 36 seconds after brake release there was a loud bang from the right engine as it disintegrated and a severe fire developed. The aircraft was at approximately 103 kts and 40 feet above the runway. At time 42 seconds, The captain started the engine failure/fire emergency drill. At time 45 seconds, the tower controller who had noticed flames from the right engine advised flight 255 that the right engine was on fire and authorised them to land on any runway. From time 50 seconds to 1 minute 05 seconds the crew attempted to raise the landing gear which never came up. The aircraft climbed to about 120 feet above the runway elevation and started a right turn, apparently in an attempt to complete a short circuit, remain visual and execute an emergency on the airport. At time 1 minute 14 seconds the captain called for the propeller to be feathered. Up to this point the crew did not know that the right engine had separated at the first stage impeller and the forward section of the engine along with the forward section of the engine along with the propeller and some cowling had fallen onto the runway At time 1minute 24 seconds the No 1 fire bottle was fired and the aircraft continued in a right turn at about 100 feet above the terrain at a very low airspeed. The engine fire continued. As the aircraft approached the College de Sacre Coeur, the angle of bank increased and the aircraft started to descend until impact. Impact occured in a nose down, right wing low attitude at approximately 80 kts. A fierce fire broke out and most of the fuselage forward of the wing was consumed by fire." The Rolls Royce Dart engine had suffered an uncontained failure. I do not presume to question or comment on events or actions except to suggest it might be worth putting into the equation for decision making? |
In earlier types flown V1/VR was within 1 second of each other, but currently now about 5 seconds.....and still 10,000 ft of runway ahead. |
First off....
Defacto...
Not all pilots are equal...sorry but true.....if you think that a 200 hour FO pulling the nose up is on par with a 10,000 hour pilot pulling the nose up, because both are 'doing the numbers' ...you just don't know.... It's become such a running joke on the sims that an 'emergency' these days, is a raw data, no A/P approach...you know the same kind of approach a guy will do in a Cessna 172..... So let's not go down the path of using some example of some African outfit, who did an over run, and busted up the plane, because I can sit here and cite example after example of guys who crashed a plane that could have been stopped, but decided to fly it to the scene of the accident instead of rolingl it there... The simple fact of the matter is that a corporate outfit that pushed the throttles forward, then realizes a few knots past V1 that he's got a fire, looks ahead to see 8000 feet of runway, is a perfectly happy non event..... If you want to plan a reduced thrust departure, where the balanced field is in the weeds, and thus a crash, into that road on the other side of the overrun, that's your business...whatever it takes to stretch those engines right? But it's a hard sell for those of us who didn't get our licenses yesterday to make the case that your flying safer then us....because you not.. Your purposefully putting passengers at risk by using up more runway, reducing obstacle clearance, forcing a go decision because you know a stop won't make it...then forcing the 200 hr FO on this leg to hand fly that whale with one good 25000 hour engine out there...while on fire, and putting the gear up, cleaning it up...and flying around the pattern in the soup, looking for another ILS, that will now be flown single engine.. Yeah sure.... |
Johns7022
You persist in making obvious your total lack of knowledge of take-off performance under Part 25 and complete ignorance of reduced power or derated power performance. By definition, the field length CANNOT be "in the weeds". In an assumed temp reduced power take-off, the plane will, be definition, perform better than the calculations. Any reduced power take-off MUST meet all the runway and obstacle clearance criteria using he reduced power setting without resetting the throttles. I'll agree with anyone here that in exceptional cases, aborting after V1 is a proper decision. But, that is exceptional cases, not the standard engine failure. I also stipulate business jets on long runways that far exceed the BFL of the day have an inherent ability to stop. In the C-5, every take-off had about 30 numbers calculed, including Vmcg,Vmca, refusal speed, AEO field length, critical field length. Before advocating stopping after V1, do you calculate a refusal speed and ASDR for every take-off? Do you calculate a Vmcg for each take-off where a wet runway, contaminated runway or crosswinds are factors? Do you use a runway analysis for each runway, including any special departure procedurefot terrain? Do you brief and do sim practice on flying the SDP? If not, you're just stringing a whizzer on "I can look out the window and judge that I can stop". Also, johns7022, just how many ASDR equals ASDA take-offs have you done to judge your stopping distance? Citations don't stop that well, if my distant memory of 2,500 hours in CII serves. GF |
And another thing
Just how many airplanes hit fuel trucks and crash having tried to continue the take-off on your planet? Here on Earth, it is just about unheard-of. But, going off the end due to poor brake usage (stopping technique KMDW), due to trying to reset the flaps past V1 (KCRW), going off the end because of lining up on the wrong runway (KLEX), going off the end by aborting past V1 when continuing the take-off would have been safer (read Boeing's report on aborted take-offs) is all too common.
GF |
Tell you what Galaxy....let's go outfit a plane where the autopilot performs the take off...if nothing on the panel lights up prior to V1, it will pull the plane off...
So when you get to the end of the runway, with a fast leaked tire, creating drag...all the while the plane burned up 10,000 feet of runway trying to get to V1...then we can discuss balanced field, running the numbers after you crawl out of the crash site..... |
John7022
I'll take your answer to mean you don't do, and probably cannot do, the proper calculations required. I, and others here, never said that pilot's should be "autopilots" flying planes, but that the calculations are necessary and should be followed. As Boeing noted, continuing too early by 1 knot might mean a lower screen height, while trying to stop 1 knot past V1 might mean an overrun of 40 knots on a field-length limited take-off. I suggest you do some real study on take off performance instead of selling the idea that pilot's should use "Kentucky windage". Statistically, you are in greater danger trying to stop and overruning than continuing the take-off. BTW, I have lost a tire on take-off, we found out about it from Shanwick when they got a call from Karup tower saying that they thought the debris on the runway was ours. GF |
Galaxy, the weakness in your thinking is that a rolling aircraft to V1, somehow guarantees a flying aircraft at VR..
I can take the wings off a 737 and go up and down the runway accelerating to V1 all day long, but we know it won't fly.... Well I guess the way you were taught is that all you gotta do is roll down the runway and look at the airspeed indicator...when it hits V1..despite the bomb/rpg that just took half your tail off and 9000 ft of runway ahead....your pulling back on the yoke. I suggest rather then focusing on on balanced field theory and aircraft certification....you do a few take offs in a plane with the airspeed indicator covered up....you might be surprised how some stick and rudder skills can do wonders for your flying..... I think you have been sitting in a box too much. |
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