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Command ejections

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Command ejections

Old 8th Sep 2013, 11:23
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Command ejections

Reading the thread on Lt Cdr London, and then out of further curiosity the BOI report of his fatal accident, I was rather baffled how this situation came about.

From what I understand from the BOI report, he ordered the student to eject, which upset the trim of the aircraft to the extent that it (rolled? pitched?) inverted, leaving him with no chance to survive his own ejection. So am I correct in inferring that the T2 had no command ejection from the rear seat? If so, why not?
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Old 8th Sep 2013, 13:39
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I always thought Command ejection meant that if the driver left the aircraft then rear crew had no choice but rear crew could leave the driver to sort things out or make his own departure.


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Old 8th Sep 2013, 14:09
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I always thought Command ejection meant that if the driver left the aircraft then rear crew had no choice but rear crew could leave the driver to sort things out or make his own departure.
IIRC the Tornado has a selector in the back for front seat/back seat/independent. 20 years ago it was a crew decision which they selected.

Back seat selection does give the option for the pilot to keep trying to save the aircraft and the nav watching the height and punching them out. It also allows for the nav to select it and punch them both out in case of pilot incapacitation.

I was at Buchan when a LU F4 was lost due to pilot incapacitation. Went into a gradual descent and the nav tried to shake him through the gap and shout at him but had to punch out and leave him as they passed 200ft. Command ejection might not have saved him, but it would have given him a chance.
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Old 8th Sep 2013, 14:28
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The way command eject works varies between aircraft types. In the Tornado if the front handle is pulled the canopy then the rear seat goes before the front. This is hard-wired through the ejection seat plumbing.

The rear cockpit can has an easy to select lever to either go on their own or for the front seat pilot to join them. In my time we always flew with 'both' selected but it was not always so with inevitable results.

In the Hawk T1 the command eject is awkwardly placed to the rear of the seat. The rear seat occupant can choose to go on their own or take the front seat with them. By contrast the front seat can go on their own and give the rear seat occupant something exciting to watch.
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Old 8th Sep 2013, 14:34
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In a trainer though - the command eject selector is normally only turned 'off' for the occasion when you have a passenger in the rear seat,I used to fly quite often as a pax in Hawks and once the pilots got to know that you were unlikely to panic and pull the handle they usually just left the command eject 'on'.
I never had much to do with Harrier T2's but I do think that the T4/8 had command eject...but too long ago now to be certain as most of my time was on single seat harriers.
I have still got my Dunsfold escape systems training booklets but of course they do not mention command eject as they were an Aircrew/FRC item !
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Old 8th Sep 2013, 14:38
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In the Hawk T1 the command eject is awkwardly placed to the rear of the seat. The rear seat occupant can choose to go on their own or take the front seat with them. By contrast the front seat can go on their own and give the rear seat occupant something exciting to watch.
Normally selected before flight !

If you think the standard Hawk T1 command eject selector is awkward you would love trying to select it on either of the 2 RAFCAM Hawks !it is in the normal place but has non standard equipment adjacent to it
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Old 8th Sep 2013, 15:13
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On the T2 Harrier though, surely command ejections should have been at least hard-wired from the back seat, if not from both seats, given that the aircraft would (probably?) be immediately unstable if one occupant ejected in the hover?
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Old 8th Sep 2013, 17:42
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Is it something to do with the fact that in a double ejection the rear seat always goes first - this is so the rocket blast of the front seat going first doesn't cook the guy in the rear seat?
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Old 8th Sep 2013, 18:01
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TA-4 Ejection Selector Lever/Switch

That was the situation in the TA-4. A selector lever/switch enabled both seats to eject OR only the rear to eject - if the rear seat aircrew/passenger ejected - leaving the pilot to fly without the canopy; which like the rear seat, also has to be 'ejected' first (so that a front seat first rocket seat did not cook the rear seat occupant).

If flying solo the pilot had to wait some 0.25/0.5 seconds after pulling the handle to have the canopy jettison and then the unoccupied rear seat eject before front seat ejected. This situation was required when passengers were in the rear seat also, so that they would not be left behind if unable to eject for whatever reason. This selection was standard. Conversely a panicked passenger ejecting could not eject the pilot.

When two pilots flying instruments, with the rear seater under the canvas hood for example, then the selector lever reversed allowed the rear seater to eject; which also ejected the front seater in turn (after canopy jettisoned automatically first). Pilots would discuss and select this option (non standard). Also this selection would be when front seater under training or two pilots in the aircraft otherwise for whatever reason.

Last edited by SpazSinbad; 8th Sep 2013 at 18:03.
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Old 8th Sep 2013, 18:07
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In a Hawk with command eject 'on' the rear seat firing will then start the front seat ejection sequence,if command eject selected off then both seats fire independently.On a training a/c (say Hawk) it was designed to have the instructor in the back seat which is why I commented previously that if carrying a passenger in the back seat then the command eject would probably be turned off.
On an operational a/c then the command eject may work both ways !
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Old 8th Sep 2013, 19:36
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Wasn't their a couple of cases of un commanded roll input on early Tornados that resulted in a crash, so they had to avoid flying near transmitters, as that was the suspect cause and if the aircraft suffered it at low level they had to bang out? They lost one avoiding an A-10 I think on the plains, the pilot not having time to warn the Nav who believing it was the said URInput ejected and as it was set at Command took the pilot with him.


..

Last edited by NutLoose; 8th Sep 2013 at 19:42.
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Old 8th Sep 2013, 20:28
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Abbreviated Accident report of the Tornado suspected UCM here

http://www.ukserials.com/pdflosses/m...1108_za603.pdf

Always had the nav set 'Both' myself. Far rather argue the toss in the bar about whether he'd been right to bang us out than have him attending my funeral.

Also, see this Phantom accident, where if command eject had been fitted it may have saved a life.

http://www.ukserials.com/pdflosses/m...0109_xt908.pdf

I flew up to the funeral, as my nav had been a good friend of the deceased.

Last edited by Fox3WheresMyBanana; 8th Sep 2013 at 21:19.
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Old 8th Sep 2013, 20:44
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The T8 didn't have command eject chaps.

We were briefed post-accident that a LP fan blade gave because of FOD damage. It went through one of the wings severing the aileron runs which resulted in a high rate of roll. It wasn't, therefore, a function of the initial ejection that made the second one out of parameters, but the increasing roll angle.
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Old 8th Sep 2013, 21:29
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In the T10/12 we would normally have the command eject set to dual (either seat could command the other) other than the initial OCU press up (VTO/VL) sorties where it would be set so that both seats could eject independently. The short delay between seats in dual meant that the front seater (who would be out 0.4 seconds after the rear) wouldn't make it if the engine quit in the hover, so better to chance a simultaneous ejection with each for their own.
Can't beat sitting on pillars of jet thrust.
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Old 8th Sep 2013, 23:54
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"DucatiST4 - Is it something to do with the fact that in a double ejection the rear seat always goes first - this is so the rocket blast of the front seat going first doesn't cook the guy in the rear seat?"

It's to do mainly with ballistics. The aircraft and everything in it is traveling forward. If the front seat ejects first, then a few milliseconds later, the back seat is beneath the rocket powered chaos that is the first ejection. Ejecting second is bad karma, in this scenario.

Much better is the following Tornado F3 scenario: Command eject set to 'Both'. Let's say that the pilot is incapacitated, so the rear seater has no other survival option than to eject. Handle pulled, linkages unlock the canopy and fire the jettison rocket motors to remove the canopy (If a failure occurs, then MDC will shatter the canopy).

After a brief delay, the rear seat ejection gun fires, raising the seat up the rails, and out of the cockpit. At a pre-determined height, a lanyard attached to the cockpit floor triggers the rocket pack, boosting the seat to a safe height for parachute deployment from ground level.

After the rear seat has ejected, the front seat will eject and follow the same sequence as the rear.

If we acknowledge that the aircraft is traveling forward, and everything ejecting is traveling forward, but (relatively) backward from the aircraft, then the sequence makes sense.

Rear seat ejected first is swept back by the slipstream and post-ejection sequence occurs automatically.

Front seat ejects second, and actions follow those of rear seat.

With the tiny time delays between seat initiation, rear first makes sense. Front first would cause problems.
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Old 9th Sep 2013, 00:13
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I seem to remember the Jag ones go out after the delay, one to the left and one right to further avoid blast and the risk of collision.
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Old 9th Sep 2013, 00:36
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Yes Nutloose, the Mk 9Bs on the Jags had handed rocket packs that sent one left and one right. No command ejection though.
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Old 9th Sep 2013, 07:43
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Ref Jaguar trainer;

http://webarchive.nationalarchives.g...34_7sept88.pdf

I remember this accident as if it was yesterday - saddest funeral I ever attended.
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