Air-Refuelling Systems Advisory Group 2010
Join Date: Dec 2002
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Been there,
I feel your pain. I've been that KC10 back there (albeit with a perfect closure of course ; )
Let's remember that it's the 135 autopilot's inability to cope with those rapid trim changes that is a big factor in that particular situation.
Interestingly, other nations, when considering a tankers action in the event of an emergency separation, do nothing ........
If the FADEC issue is still there, then that is indeed an issue, but I thought there was a modification to allow full range of the engine parameters ?
Diff may know .......
I feel your pain. I've been that KC10 back there (albeit with a perfect closure of course ; )
Let's remember that it's the 135 autopilot's inability to cope with those rapid trim changes that is a big factor in that particular situation.
Interestingly, other nations, when considering a tankers action in the event of an emergency separation, do nothing ........
If the FADEC issue is still there, then that is indeed an issue, but I thought there was a modification to allow full range of the engine parameters ?
Diff may know .......
Join Date: Nov 2000
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Diff would like to see a quantitative analysis of the closure rates Ben There experienced, and the subsequent rates of acceleration/deceleration and seperation parameters. Otherwise it's just another breakaway; a copy of the mishap report might help.
IIRC there have been some collisions between boom tankers and receivers, but I am not aware of any recorded cases where a 'soft kill' of the tanker, by the crew overboosting its engines, have resulted in saving lives. Although I would be keen to read such a report. IT's less of an issue on P&D missions of course.
Notwithstanding the thrust limits set by engine manufacturers (NOT by Boeing or Airbus - who only make the aeroplane to which the engines are bolted), an Airworthiness Authority would have to consider very carefully whether allowing crews to operate outside of design parameters met ALARP principles, to start with. I suspect they would want the crews to stick to the limits; and I would argue that the 'fire or medal' argument is a matter of philisophical difference between operators.
Personally, I have trained and evaluated a number of Tanker and Receiver crews, in Boom and P&D ops, and I believe that while exceptionally qualified operators, like Ben There, might benefit from being able to ride the knife-edge, the average pilot, on an average day, etc, would benefit from protection beyond the edge of the envelope. NB that the Bus allows operation to the limits, just not beyond them.
Specifally for the A330MRTT; there are 3 engine types available and all allow access to maximum rated thrust applicable to the given environment, with protection against shelling-out as Ben There did.
FFP mate - if you press TOGA on your TRC and 'firewall' your throttles - you get TOGA (MCT factored for ram air effect?) same deal on a 'Bus with CF6's - only no visible TRC, just push the thrust levers forwards to the stops. From what Ben There says - if you do the same on the KC135, you get a Class 1 mishap!
You also make a good point that it's the deficiencies of the KC-135 autopilot that brings about the sort of situation Ben There found himself in. Therefore, if Boeing are offering the same standard of automation as the KC-135, then perhaps he has a point, but we would need to assess the, as yet unbuilt, Boeing product before his argument has any merit at all.
IIRC there have been some collisions between boom tankers and receivers, but I am not aware of any recorded cases where a 'soft kill' of the tanker, by the crew overboosting its engines, have resulted in saving lives. Although I would be keen to read such a report. IT's less of an issue on P&D missions of course.
Notwithstanding the thrust limits set by engine manufacturers (NOT by Boeing or Airbus - who only make the aeroplane to which the engines are bolted), an Airworthiness Authority would have to consider very carefully whether allowing crews to operate outside of design parameters met ALARP principles, to start with. I suspect they would want the crews to stick to the limits; and I would argue that the 'fire or medal' argument is a matter of philisophical difference between operators.
Personally, I have trained and evaluated a number of Tanker and Receiver crews, in Boom and P&D ops, and I believe that while exceptionally qualified operators, like Ben There, might benefit from being able to ride the knife-edge, the average pilot, on an average day, etc, would benefit from protection beyond the edge of the envelope. NB that the Bus allows operation to the limits, just not beyond them.
Specifally for the A330MRTT; there are 3 engine types available and all allow access to maximum rated thrust applicable to the given environment, with protection against shelling-out as Ben There did.
FFP mate - if you press TOGA on your TRC and 'firewall' your throttles - you get TOGA (MCT factored for ram air effect?) same deal on a 'Bus with CF6's - only no visible TRC, just push the thrust levers forwards to the stops. From what Ben There says - if you do the same on the KC135, you get a Class 1 mishap!
You also make a good point that it's the deficiencies of the KC-135 autopilot that brings about the sort of situation Ben There found himself in. Therefore, if Boeing are offering the same standard of automation as the KC-135, then perhaps he has a point, but we would need to assess the, as yet unbuilt, Boeing product before his argument has any merit at all.
Thread Starter
'Firewalling' the engines in a VC10 at AAR levels would probably lead to 4 x engine surges and a significant loss of thrust and possible engine damage - it is never even considered as an 'escape' method. More modern aircraft with better engine fuel control systems will, as D-IFF states, give you max continuous thrust factored for the environment (temp / alt / TAS etc) in response to the associated thrust demand method (TOGA buttons or thrust lever movement).
Rapid closure to the astern position seems more likely with, for example, the Option 2 RV Delta method. Purely due to the fact that receiver / tanker speeds are less standardised than for Option 1. Flying at receiver AAR speed with the receiver joining to (real) observation at no more than AAR speed +20KIAS is a lot simpler - even if it means the receivers slowing down slightly earlier - and is less likely to result in an 'overrun'.
About the only seriously dangerous join I can recall resulted in a fatal accident where only the captain of the Victor crew survived. The receiver pilot broke all SOPs, came hammering in way too fast, then tried to pull up and despite full airbrake, clouted the Victor's tail - which detached. The receiver crew survived.
Large receiver bow waves affecting the tanker autopilot is not that common in the RAF; I've experienced it during early TriStar receiver trials and with the Nimrod AEW3 - neither of which are current receiver types. It is likely to be more significant with something like a C-5 against a boom tanker, I would imagine.
Of course the only real way to prevent accidents is to beat 'erratic and excessive' closure rates out of receiver pilots with a large cudgel. Send them home if necessary - I don't know whether Arters ever sent anyone home, I've only done so once when a FAF Mirage appeared not to understand basic RT calls. But if there's any doubt, there must be no doubt.
And make the RV and join process as simple and straightforward as possible by providing a stable, predictable tanker platform flying at receiver AAR speed - the receivers flying at AAR speed +20 with a 1 mile rollout works just fine.
Rapid closure to the astern position seems more likely with, for example, the Option 2 RV Delta method. Purely due to the fact that receiver / tanker speeds are less standardised than for Option 1. Flying at receiver AAR speed with the receiver joining to (real) observation at no more than AAR speed +20KIAS is a lot simpler - even if it means the receivers slowing down slightly earlier - and is less likely to result in an 'overrun'.
About the only seriously dangerous join I can recall resulted in a fatal accident where only the captain of the Victor crew survived. The receiver pilot broke all SOPs, came hammering in way too fast, then tried to pull up and despite full airbrake, clouted the Victor's tail - which detached. The receiver crew survived.
Large receiver bow waves affecting the tanker autopilot is not that common in the RAF; I've experienced it during early TriStar receiver trials and with the Nimrod AEW3 - neither of which are current receiver types. It is likely to be more significant with something like a C-5 against a boom tanker, I would imagine.
Of course the only real way to prevent accidents is to beat 'erratic and excessive' closure rates out of receiver pilots with a large cudgel. Send them home if necessary - I don't know whether Arters ever sent anyone home, I've only done so once when a FAF Mirage appeared not to understand basic RT calls. But if there's any doubt, there must be no doubt.
And make the RV and join process as simple and straightforward as possible by providing a stable, predictable tanker platform flying at receiver AAR speed - the receivers flying at AAR speed +20 with a 1 mile rollout works just fine.
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Yes I have sent two home. One was a Station Commander who showed his lack of continuity rather too well and the other was a young lady of a Far Eastern air force for whom it was all too much and her oscillations behind the drogue were fully exploring her aircrafts envelope. Any attempt to react to either by the tanker would have been impossible because the situation was changing so rapidly.
