V2
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Sorry John I meant elected V1.
As per Concord they elected middle ground @ 150kts, but this then has no tolerance by crew.
A failure like QF32 either side but close to V1, would be a case of not having a good day.
As per Concord they elected middle ground @ 150kts, but this then has no tolerance by crew.
A failure like QF32 either side but close to V1, would be a case of not having a good day.
Good discussion, and I really value the ops engineering insights from JT.
My humble opinion on this: while I find the technical descriptions and changes in the orders over time very interesting, most of the very pedantic consideration is academic and not useful practically.
I wouldn't expect to find any pilots in Australia flying transport category who don't understand the concept that you must have started doing something to stop by V1.
The discussion about V1-1 or V1-0.000001, and deciding to go after commencing a stop - all a bit of a waste of time. The stress which occurs with a V1 stop/go will, for 99% of pilots, not afford the required headspace to do something like change the mind. In the sim when you're expecting - maybe yes.
If the runway speeds are brake energy limited, it might be better to commence a stop above v1 and risk a brake fire. If runway length was limiting, it would probably be best to go. All interesting to discuss, but who is going to have that sort of headspace available to decide when it all turns to ****?
As someone said earlier, KISS.
The only reason I'd actually commence a stop after v1 would* be if the aircraft is definitely not going to fly - like a structural or controllability failure.
My humble opinion on this: while I find the technical descriptions and changes in the orders over time very interesting, most of the very pedantic consideration is academic and not useful practically.
I wouldn't expect to find any pilots in Australia flying transport category who don't understand the concept that you must have started doing something to stop by V1.
The discussion about V1-1 or V1-0.000001, and deciding to go after commencing a stop - all a bit of a waste of time. The stress which occurs with a V1 stop/go will, for 99% of pilots, not afford the required headspace to do something like change the mind. In the sim when you're expecting - maybe yes.
If the runway speeds are brake energy limited, it might be better to commence a stop above v1 and risk a brake fire. If runway length was limiting, it would probably be best to go. All interesting to discuss, but who is going to have that sort of headspace available to decide when it all turns to ****?
As someone said earlier, KISS.
The only reason I'd actually commence a stop after v1 would* be if the aircraft is definitely not going to fly - like a structural or controllability failure.
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"The only reason I'd actually commence a stop after v1 wouldn't be if the aircraft is definitely not going to fly."
No that makes sense to me, no point accelerating to a certain crash. But very hard to know in that short time. Increasing vibration on any control surface would do it for me.
No that makes sense to me, no point accelerating to a certain crash. But very hard to know in that short time. Increasing vibration on any control surface would do it for me.
Critique the decisions made here. L-1011 abort following lift off when the stall warning/stick shaker activated.
http://libraryonline.erau.edu/online...s/AAR93-04.pdf
Re Concorde had it attempted an abort from the report
The relevant speeds for the take off were V1: 150 kt, VR: 198 kt, V2: 220 kt. They ran over the metal strip, which precipitated the event, at 175 kt, 25 kt past V1.
Was there not some discussion that an abort, and the trajectory the aircraft would have taken, would may have lead to a collision with a 747, and was the presumed reason he rotated some 11 kt early?
http://libraryonline.erau.edu/online...s/AAR93-04.pdf
Re Concorde had it attempted an abort from the report
Consequences of Aborting the Takeoff
Two simulations of a possible acceleration-stop were performed, one based on the aircraft’s speed when the rotation was commenced (that is to say in fact the first moment when the crew could have been warned by unusual sensations), at 183 kt, the other at 196 kt, when the FE said what can be understood as “stop”.
The simulations were conducted with the following hypotheses:
• braking on seven wheels, to take into account the destruction of tyre No 2,
• braking torque available at nominal value until the maximum energy indicated in the Flight Manual (70 MJ), increased by 10%,
• use of thrust reversers on engines 1, 3 and 4. With this set of hypotheses, it appears that the residual speed of the aircraft at the end of the runway would have been 74 kt for a takeoff aborted at 183 kt and 115 kt for a takeoff aborted at 196 kt. These figures show that an aborted takeoff would have led to a runway excursion at such a speed that, taking into account the fire, the result would probably have been catastrophic for the aircraft and its occupants.
Two simulations of a possible acceleration-stop were performed, one based on the aircraft’s speed when the rotation was commenced (that is to say in fact the first moment when the crew could have been warned by unusual sensations), at 183 kt, the other at 196 kt, when the FE said what can be understood as “stop”.
The simulations were conducted with the following hypotheses:
• braking on seven wheels, to take into account the destruction of tyre No 2,
• braking torque available at nominal value until the maximum energy indicated in the Flight Manual (70 MJ), increased by 10%,
• use of thrust reversers on engines 1, 3 and 4. With this set of hypotheses, it appears that the residual speed of the aircraft at the end of the runway would have been 74 kt for a takeoff aborted at 183 kt and 115 kt for a takeoff aborted at 196 kt. These figures show that an aborted takeoff would have led to a runway excursion at such a speed that, taking into account the fire, the result would probably have been catastrophic for the aircraft and its occupants.
Was there not some discussion that an abort, and the trajectory the aircraft would have taken, would may have lead to a collision with a 747, and was the presumed reason he rotated some 11 kt early?
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Wow that's ballsy after take-off!!
It paid off in that case.
As with Concord the fact of heavily on fire certainly had a high probability on not ending well for all on board. Only with luck not more than 4 people were not killed (6 others injured with burns I assume) in the hotel it crashed.
I don't recall the 747, but the pilot at 150kt was committed to take regardless even though the upper speed of V1 from memory was 164 kt (11 kt over then if upper limit used).
It paid off in that case.
As with Concord the fact of heavily on fire certainly had a high probability on not ending well for all on board. Only with luck not more than 4 people were not killed (6 others injured with burns I assume) in the hotel it crashed.
I don't recall the 747, but the pilot at 150kt was committed to take regardless even though the upper speed of V1 from memory was 164 kt (11 kt over then if upper limit used).
Good discussion, and I really value the ops engineering insights from JT.
This observation came to the fore during the numerous simulator sessions I attended during my career where pilots invariably cocked up rejected take offs on marginal length runways especially wet surface. It could have been due to the surprise factor for example, or delays in extending speed brakes and even rejected a take off because of a gut feeling that something was not quite right. Even though nothing wrong with the aircraft.
I quietly came to the conclusion from the time I had my first command that 15 knots below V1 I would continue the take off. Screen height might be compromised but statistically I felt I would not hit a tree branch during climb-out. To this day I remain comfortable with that policy regardless of legal ramifications.
I kept my thoughts to myself about all this because to inform a co-pilot during the before take off safety brief would only invite pursed lips and eyes rolling in terror at such a heinous decision requiring a dobbing in to management. The CVR was kept in the dark for obvious reasons.
in short, my decision in this matter of V1 was based upon reading world wide accident reports of fatal high speed aborts which need not have occurred but for mis-judgement by the pilot. In other words learning from someone else's experience, which is no bad thing
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Judd I assume you are talking just an engine failure event "with no extras"?
Or regardless 15 kt below you will continue to blast of regardless of all else.
P.S. 15 Kt below on a craft on fire will be almost certain death in the Concord or other scenario (tail wind!).
Or regardless 15 kt below you will continue to blast of regardless of all else.
P.S. 15 Kt below on a craft on fire will be almost certain death in the Concord or other scenario (tail wind!).
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Re a personal pad on V1 .. not at all uncommon. Indeed, in the analysis of the mishap in the earlier link (megan #84), the operator had a definite policy to shade the call below V1 ..
Another caveat to keep in mind. If the takeoff is at very low weight with a minimum speed schedule (ie looking at the Vmcg-limited V1 situation or even a bit higher with a strong crosswind (as it turns out on the day .. from the wrong side), choosing to use a lower than scheduled V1 just might see the aeroplane out of control for the critical OEI failure and very smartly off into the grass. In general, a real-world-Vmcg-on-the-day directional departure is sufficiently rapid to bring tears to the eyes ..
There are strategies available to minimise this sort of risk but, however you might choose to approach the problem, one should be aware of it at the very least and not needlessly expose the operation to the risk.
Another caveat to keep in mind. If the takeoff is at very low weight with a minimum speed schedule (ie looking at the Vmcg-limited V1 situation or even a bit higher with a strong crosswind (as it turns out on the day .. from the wrong side), choosing to use a lower than scheduled V1 just might see the aeroplane out of control for the critical OEI failure and very smartly off into the grass. In general, a real-world-Vmcg-on-the-day directional departure is sufficiently rapid to bring tears to the eyes ..
There are strategies available to minimise this sort of risk but, however you might choose to approach the problem, one should be aware of it at the very least and not needlessly expose the operation to the risk.
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Off track a bit (sorry) John did you play with the Nomad? and its certification?
I seem to recall your name in a thread about them??
I learned lots about how to operate that aircraft at a conference in NZ ( blue line was your friend) a very interesting seminar and regulator present.
I seem to recall your name in a thread about them??
I learned lots about how to operate that aircraft at a conference in NZ ( blue line was your friend) a very interesting seminar and regulator present.
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Finished uni on a cadetship (with then Supply) for the Bend. Spent some time following as a design engineer/aerodynamicist on the Nomad program before heading off to DCA. Did some mod climb test work on the N24As up north some years after. Years later back again to head up field support after djpil headed off to the US for some fun and games.
Some enthusiastic operators in the NZ arena. Do you recall any factory names from the conference ?
Although I had various involvements with aspects of its certification over the years, a far better chap for Nomad certification questions is djpil who spent many years on the program, ending up in lofty engineering heights ... Apart from that, he's an all round good sort of chap who would be more than happy to field questions.
Some enthusiastic operators in the NZ arena. Do you recall any factory names from the conference ?
Although I had various involvements with aspects of its certification over the years, a far better chap for Nomad certification questions is djpil who spent many years on the program, ending up in lofty engineering heights ... Apart from that, he's an all round good sort of chap who would be more than happy to field questions.
A good example of pressure vs decision making is a subtle engine failure on final in a turboprop.
If done correctly while the levers are back on idle, the speed loss which occurs before recognition and corrective action can be significant.
I've seen this stuffed up many times where crew instinctively begin to run out of airspeed, and eventually start decide to push up the operating engine and go around. As the loss of control approaches, the only thing to be done is reduce the operating engine power.
Every transport pilot understands that reducing power on the operating engine will increase controllability/decrease Vmca, but so few have the brain space to implement this - only sim instructors or examiners on type who've seen it over and over and who are regularly exposed.
This is why V1 concepts have to be kept simple - knowing and understanding something is completely different to being able to reliably apply deep knowledge in high pressure/low time available situations.
If done correctly while the levers are back on idle, the speed loss which occurs before recognition and corrective action can be significant.
I've seen this stuffed up many times where crew instinctively begin to run out of airspeed, and eventually start decide to push up the operating engine and go around. As the loss of control approaches, the only thing to be done is reduce the operating engine power.
Every transport pilot understands that reducing power on the operating engine will increase controllability/decrease Vmca, but so few have the brain space to implement this - only sim instructors or examiners on type who've seen it over and over and who are regularly exposed.
This is why V1 concepts have to be kept simple - knowing and understanding something is completely different to being able to reliably apply deep knowledge in high pressure/low time available situations.
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A good example of pressure vs decision making is a subtle engine failure on final in a turboprop.
.. much the same observation for a jet .. standard exercise is to fail one on mid finals and see how long before the troops pick it up .. certainly sorts those who have a good scan from the rest.
... but so few have the brain space to implement this - only sim instructors or examiners on type who've seen it over and over and who are regularly exposed.
This is why V1 concepts have to be kept simple - knowing and understanding something is completely different to being able to reliably apply deep knowledge in high pressure/low time available situations.
Hole in one, good sir, methinks
.. much the same observation for a jet .. standard exercise is to fail one on mid finals and see how long before the troops pick it up .. certainly sorts those who have a good scan from the rest.
... but so few have the brain space to implement this - only sim instructors or examiners on type who've seen it over and over and who are regularly exposed.
This is why V1 concepts have to be kept simple - knowing and understanding something is completely different to being able to reliably apply deep knowledge in high pressure/low time available situations.
Hole in one, good sir, methinks
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"Some enthusiastic operators in the NZ arena. Do you recall any factory names from the conference ?"
No don't remember that's got to be over 20 years ago now.
The enthusiastic operators stunned factory reps including Alison and CAA- when several operators of the Nomad said "regardless of what is left ahead, any engine failure below Blue Line during take-off we will abort!"
No don't remember that's got to be over 20 years ago now.
The enthusiastic operators stunned factory reps including Alison and CAA- when several operators of the Nomad said "regardless of what is left ahead, any engine failure below Blue Line during take-off we will abort!"
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No don't remember that's got to be over 20 years ago now.
That's around my time in field service. Do the names Tiz Quagliatini or Terry Steen ring any bells ? One or both of those fine chaps (the field service reps) ought to have been in attendance.
.. "regardless of what is left ahead, any engine failure below Blue Line during take-off we will abort!"
Certainly a useful consideration for FAR 23 aircraft other than with a gazillion foot long runway ... especially for the N24A, which was probably the subject of the conference comments, and was very much OEI WAT-limited.
I always had much the same view in light twin flying years ago .. unless the weight was low, the overrun hazardous, and the terrain ahead for climb quite benign. Raised a few eyebrows during GA instrument rating renewals when my brief was along the lines of .. "touch a throttle prior to x ft on the altimeter and I'll close the other one and land ahead". Strange .. never had an examiner test my mettle on that one. I tell a fib .. Al B. pulled an engine at liftoff on my Partenavia endorsement at EN, years ago .. stopped with plenty to spare.
One caveat, the US government Nomads were, as I recall, transport certificated.
That's around my time in field service. Do the names Tiz Quagliatini or Terry Steen ring any bells ? One or both of those fine chaps (the field service reps) ought to have been in attendance.
.. "regardless of what is left ahead, any engine failure below Blue Line during take-off we will abort!"
Certainly a useful consideration for FAR 23 aircraft other than with a gazillion foot long runway ... especially for the N24A, which was probably the subject of the conference comments, and was very much OEI WAT-limited.
I always had much the same view in light twin flying years ago .. unless the weight was low, the overrun hazardous, and the terrain ahead for climb quite benign. Raised a few eyebrows during GA instrument rating renewals when my brief was along the lines of .. "touch a throttle prior to x ft on the altimeter and I'll close the other one and land ahead". Strange .. never had an examiner test my mettle on that one. I tell a fib .. Al B. pulled an engine at liftoff on my Partenavia endorsement at EN, years ago .. stopped with plenty to spare.
One caveat, the US government Nomads were, as I recall, transport certificated.
A good example of pressure vs decision making is a subtle engine failure on final in a turboprop.
If done correctly while the levers are back on idle, the speed loss which occurs before recognition and corrective action can be significant.
I've seen this stuffed up many times where crew instinctively begin to run out of airspeed, and eventually start decide to push up the operating engine and go around. As the loss of control approaches, the only thing to be done is reduce the operating engine power.
If done correctly while the levers are back on idle, the speed loss which occurs before recognition and corrective action can be significant.
I've seen this stuffed up many times where crew instinctively begin to run out of airspeed, and eventually start decide to push up the operating engine and go around. As the loss of control approaches, the only thing to be done is reduce the operating engine power.
Just prior to turning for finals, trouble was experienced in the pitch-lock mechanism of the no. 1 prop. The prop was feathered and the approach was continued with full flaps, but without immediately increasing power on the remaining engine. The high rate of descent was not arrested during the turn, resulting in a slightly low altitude. Power was added and speed reduced to control the descent rate, but the crew were unable to maintain runway heading. An overshoot was attempted, but the speed had dropped below minimum control speed. The left wing dropped as full power was applied to the no. 2 engine. The wing struck the ground and the aircraft crashed, coming to rest 740 feet abeam the runway threshold. Fuel tanks ruptured and caused a fire, which was quickly extinguished.
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Sort of like F-27 FNH.
Not really. Joe was caught out by the certification basis for the aircraft prior to the changes to incorporate the PAMC report recommendations. He well and truly knew he was OEI .. just didn't have the background knowledge that OEI plus AEO landing flap was a bad idea if you intended to play with thrust on the operating engine.
Once the changes came in OEI was limited to approach flap for missed approach considerations and made OEI landings a bit more comfortable. There is an old thread on the mishap -
http://www.pprune.org/pacific-genera...st-1965-a.html
Not really. Joe was caught out by the certification basis for the aircraft prior to the changes to incorporate the PAMC report recommendations. He well and truly knew he was OEI .. just didn't have the background knowledge that OEI plus AEO landing flap was a bad idea if you intended to play with thrust on the operating engine.
Once the changes came in OEI was limited to approach flap for missed approach considerations and made OEI landings a bit more comfortable. There is an old thread on the mishap -
http://www.pprune.org/pacific-genera...st-1965-a.html
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Both those names ring bells John, but that could have been post conference too. It was a well attended meeting and my first Nomad experience (doing a export C of A on an aircraft my company just brought).
These statements were the point of much discussion with some similar comments and views to the ones about V1 here.
The CAA attendants took their caps off and the topic was discussed openly. That certainly would not happen in Australia today. That conference is probably why I am so adamant reaching V1 does not mean my decision is made, and I will continue take-off.
Rather I should take-off but is there a better reason to stay?
These statements were the point of much discussion with some similar comments and views to the ones about V1 here.
The CAA attendants took their caps off and the topic was discussed openly. That certainly would not happen in Australia today. That conference is probably why I am so adamant reaching V1 does not mean my decision is made, and I will continue take-off.
Rather I should take-off but is there a better reason to stay?
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I think the present Industry view that one should keep going unless there is an overwhelming reason to suspect that the bird just isn't going to fly ... is about right .. caveat is that we are talking FAR 25 aeroplanes rather than puddle jumpers. For the latter stopping usually is more attractive than going.
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That statement John we will "usually" agree with you 100%.
And thanks for your input, you write and explain well - things I have trouble with, and many of my era of education also. But I will take the blame as I never tried at English, I regret that now.
And thanks for your input, you write and explain well - things I have trouble with, and many of my era of education also. But I will take the blame as I never tried at English, I regret that now.
"Do you recall any factory names from the conference ?" In Queenstown in the early '90s. Somewhere I have a photo of attendees. From memory, Arthur and Tiz not Terry.