Hands off the controls during carrier catapault launches
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Hands off the controls during carrier catapault launches
Talking to an aviation medicine doctor about somosogravic effect where pilots have been known to be fooled by perceived acceleration and react incorrectly. We discussed aircraft carrier ops and I pondered why naval aviators are seemingly not affected especially on catapult launches.
Personally I think that some accidents that have been put down to somosogravic effect are more the result of poor instrument flying ability rather than a medical event. The doc said naval aviators are especially vulnerable to this somosogravic effect (I hope I spelt it correctly) and said that is why just before a launch the pilots take their hands of the controls so as not be caught by this situation and therefore are not prone to pushing forward on the control column in response.
I thought he ws pulling my leg but he was serious. I thought the reason on catapault launches that pilots keep their hands away from the throttles and from the control column was to avoid involuntary moving these controls due to the force of the launch.
What is the true reason for pilots keeing their hands of the controls during a launch?
Personally I think that some accidents that have been put down to somosogravic effect are more the result of poor instrument flying ability rather than a medical event. The doc said naval aviators are especially vulnerable to this somosogravic effect (I hope I spelt it correctly) and said that is why just before a launch the pilots take their hands of the controls so as not be caught by this situation and therefore are not prone to pushing forward on the control column in response.
I thought he ws pulling my leg but he was serious. I thought the reason on catapault launches that pilots keep their hands away from the throttles and from the control column was to avoid involuntary moving these controls due to the force of the launch.
What is the true reason for pilots keeing their hands of the controls during a launch?
Last edited by Centaurus; 4th Jul 2012 at 13:35.
Both the effects you mention come into play. F4 (K model) had levers to hook the fingers of your left hand around to stop your arm (and the throttles) being dragged backwards by the acceleration. Piece of string set the stick position, but you couldn't let go of the stick in a lot of types. Many newer jets were, most certainly, hands off at launch.
In the earlier jets (eg Sea Hawk, Venom etc), the relatively unsophisticated AH's tended to give a nose up and right turn indication during the acceleration. At night, this could cause accidents if the pilot didn't ignore the indications during the short period before the instrument re-erected. However, launching hands-off was not an relevant option.
The Buccaneer had very low pitch stability in the take-off/landing configuration. Several accidents occurred during trials which were ascribed to the pilot inadvertently moving his hand back under acceleration. Accordingly, the hands off technique was employed which cured the problem (at least, until the Mk2 with slipper tanks reached front-line service, but that was different). There wasn't any particular problem with this; you had to calculate the trim setting fairly carefully, and the setting was confirmed by an outside observer with a set of flip cards showing you what the tailplane trim indicated on the scale on the fin actually was. Once airborne, the aircraft started to climb as the speed increased (slowly, in the case of the Mk1!), so one usually placed one's hand behind the control column and eased gently forward, trimming the while, until the aircraft had accelerated sufficiently for one to grasp the shiny levers and aviate normally.
We kept our hands firmly on the throttles, though, throughout.
Dunno anything about the F4. Noisy beasts.
The Buccaneer had very low pitch stability in the take-off/landing configuration. Several accidents occurred during trials which were ascribed to the pilot inadvertently moving his hand back under acceleration. Accordingly, the hands off technique was employed which cured the problem (at least, until the Mk2 with slipper tanks reached front-line service, but that was different). There wasn't any particular problem with this; you had to calculate the trim setting fairly carefully, and the setting was confirmed by an outside observer with a set of flip cards showing you what the tailplane trim indicated on the scale on the fin actually was. Once airborne, the aircraft started to climb as the speed increased (slowly, in the case of the Mk1!), so one usually placed one's hand behind the control column and eased gently forward, trimming the while, until the aircraft had accelerated sufficiently for one to grasp the shiny levers and aviate normally.
We kept our hands firmly on the throttles, though, throughout.
Dunno anything about the F4. Noisy beasts.
Last edited by Schiller; 4th Jul 2012 at 14:23.
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hands off
I have no personal knowledge (my daugher delights in telling me that I know a little about a lot), however ......
Tom Eales " A Passion for Flying" p 45:
"The technique used for launching a Bucc was "hands off". a tailplane trim setting was calculated...........etc. This was set and the theory was that it would rotate the aircraft into the correct attitude for the initial climb without intervention from the pilot.Once positioned on the catapult........the pilot would lock his left arm behind the throttles to ensure they remained at full power, raise his right arm to accept the launch, then place it on his right thigh, close to, but not holding, the control column.
The acceleration was phenomenal, then everything stopped when you became airborne. It was like being fired into jelly. You then carefully took control.........!!!
Tom Eales " A Passion for Flying" p 45:
"The technique used for launching a Bucc was "hands off". a tailplane trim setting was calculated...........etc. This was set and the theory was that it would rotate the aircraft into the correct attitude for the initial climb without intervention from the pilot.Once positioned on the catapult........the pilot would lock his left arm behind the throttles to ensure they remained at full power, raise his right arm to accept the launch, then place it on his right thigh, close to, but not holding, the control column.
The acceleration was phenomenal, then everything stopped when you became airborne. It was like being fired into jelly. You then carefully took control.........!!!
Do a Hover - it avoids G
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Centaurus
I pondered why naval aviators are seemingly not affected especially on catapult launches.
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The F4K had a SPD (stick positioning device) on the forward centre console. Tail plane angle was calculated according to weight, end speed etc. On the catapult, the pilot positioned the stick with SPD declutched, to achieve required angle. There was an internal indicator and one of the deck crew displayed the actual tailplane angle (on a handheld board) to the pilot who adjusted accordingly. When it was correct, the SPD was clutched to that position.
Throttles were manually held at full reheat, and on cat firing, off you went for the thrill of lifetime (or one of them).
The SPD did slip occasionally, allowing excess angle on the tailplane. This was generally insignificant unless launching at MLS -.
Hands were on the controls, but imputs were not made until after the cat stroke and aircraft rotation was complete.
Throttles were manually held at full reheat, and on cat firing, off you went for the thrill of lifetime (or one of them).
The SPD did slip occasionally, allowing excess angle on the tailplane. This was generally insignificant unless launching at MLS -.
Hands were on the controls, but imputs were not made until after the cat stroke and aircraft rotation was complete.
Last edited by blaireau; 4th Jul 2012 at 15:22.
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Personally I think that some accidents that have been put down to somosogravic effect are more the result of poor instrument flying ability rather than a medical event
Not being a driver I've experianced this affect as a pax during a low level abort due to WX. While low level in a Hawk we encountered low cloud and immediately pitched up to break cloud cover. To this day I'm convinced we pitched so much that we inverted and we're flying back towards our original direction from which we came, still wrong way up, but in fact we broke cloud cover and my driver completed a roll (just for the heck of it). So I can see how these sudden effects can act upon the body and mind.
But (I'm contradicting myself now
) thankfully the guy up front knew his ass from his control column and flew on instruments.I'll get my coat ,
BW
Last edited by Bubblewindow; 5th Jul 2012 at 05:03.
I did a few cat launches with the USN.
It wasn't "hands off".
But it wasn't "hands gripping" either!!
It is a fairly violent manoeuvre, so one does what is right - keep hands close and on, but go with the flow!! If control inputs are needed, then do it - if not, then let God take control!
It all happens quite quickly, so natural responses seem to me to work OK!
I didn't see a need for a decisive "on or off" dictat!!
But there will be others with a whole lot more experience than I who might offer an alternative opinion!!
It wasn't "hands off".
But it wasn't "hands gripping" either!!
It is a fairly violent manoeuvre, so one does what is right - keep hands close and on, but go with the flow!! If control inputs are needed, then do it - if not, then let God take control!
It all happens quite quickly, so natural responses seem to me to work OK!
I didn't see a need for a decisive "on or off" dictat!!
But there will be others with a whole lot more experience than I who might offer an alternative opinion!!
Suspicion breeds confidence
I heard a story that after a couple of Bucc crashes on Victorious, either Blackburn or Boscombe sent a test pilot to fly the Bucc Mk1 to prove that it was pilot error. He went into the drink on his first launch but luckily lived to tell the tale.
Further investigations were made and procedures adjusted!
Further investigations were made and procedures adjusted!
Last edited by Navaleye; 5th Jul 2012 at 00:02.
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Yep JDE from Boscombe Down and ( S who was a RAF 801 squadron observer) to 801 squadron on Hms Victorious, was on deck ,when he went in. Off Singapore. Also when the other one went in G and E, from 801 squadron whilst we were on a workups off the Lizard ,before deploying.
Last edited by david parry; 5th Jul 2012 at 07:10.
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Forgive the slight thread creep but the sea harrier launch off the ski jump needed careful stick handling. The trim and nozzle angle was calculated for the conditions and AUW etc and usually resulted in a launch with no pitch input required until the acceleration mode.
This was completely different from the land based take off where a large back stick movement was needed at nozzle rotation to avoid bashing the nose!
A certain GR 3 pilot never quite got the hang of this during his time on HMS Hermes in the Falklands and ended up clearing his wing at least twice with enormous amounts of instantaneous AOA.
Poor fellow even managed to land in the catwalk!
Never was an RAF officer happier to procede ashore to Stanley.
ES
This was completely different from the land based take off where a large back stick movement was needed at nozzle rotation to avoid bashing the nose!
A certain GR 3 pilot never quite got the hang of this during his time on HMS Hermes in the Falklands and ended up clearing his wing at least twice with enormous amounts of instantaneous AOA.
Poor fellow even managed to land in the catwalk!
Never was an RAF officer happier to procede ashore to Stanley.
ES
Last edited by Edmund Spencer; 5th Jul 2012 at 08:19.
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In the Scimitar the routine was closed fist behind thrust levers to prevent any inadvertent dragging back. Hold the stick normally but with your elbow into your stomach/chest.
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A4G Skyhawk Catapult Control Technique
A4G Skyhawk Catapult Launch as per NATOPS was to have correct trim and flap setting. A handle next to throttle was swung down so that at full power the pilot could grasp both the throttle and this handle to prevent throttle slipping during launch. Also the throttle friction grip was wound to 11 (as per 'Spinal Tap').
The pilot brought right hand cupped into the pit of stomach awaiting the slow backwards drift of the stick (under hydraulic control so movement slow during catapult stroke) to grasp the stick as it reached stomach just as the aircraft left the bow, to fly nose up in a positive rate of climb. Then the throttle catapult hand grip swung back out of the way and throttle grip loosened for ordinary flight. And trim trim trim. Flaps up wheels up.
Night catapults were fraught with niggles such as those highlighted here:
Dark Night Takeoffs
Click thumbnail for the bigger pic (11):
The pilot brought right hand cupped into the pit of stomach awaiting the slow backwards drift of the stick (under hydraulic control so movement slow during catapult stroke) to grasp the stick as it reached stomach just as the aircraft left the bow, to fly nose up in a positive rate of climb. Then the throttle catapult hand grip swung back out of the way and throttle grip loosened for ordinary flight. And trim trim trim. Flaps up wheels up.
Night catapults were fraught with niggles such as those highlighted here:
Dark Night Takeoffs
Click thumbnail for the bigger pic (11):
Thread drift warning.
Whilst we're mentioning general illusions; flying into Frankfurt 25? one night , busy crossing road traffic on finals gave visual illusion of aircraft drifting
Back onto instruments until past road!
Whilst we're mentioning general illusions; flying into Frankfurt 25? one night , busy crossing road traffic on finals gave visual illusion of aircraft drifting
Back onto instruments until past road!
Last edited by Basil; 5th Jul 2012 at 09:21.
A certain GR 3 pilot never quite got the hang of this during his time on HMS Hermes in the Falklands and ended up clearing his wing at least twice with enormous amounts of instantaneous AOA.
Poor fellow even managed to land in the catwalk!
Never was an RAF officer happier to procede ashore to Stanley.
Poor fellow even managed to land in the catwalk!
Never was an RAF officer happier to procede ashore to Stanley.
His "landing in the catwalk" does not give fair comment on the weather pertaining, or the operational pressure. He actually just put one outrigger off the edge, and tilted slightly - and the jet was very quickly righted by deck personnel. So let's not make an assumed conclusion that the fault was all attributable to the pilot. Again, if my memory is correct, he landed heavyweight with bombs on the wings, rather than jettisonning them into the sea after a sortie when targets were not available.
But, yes. I think he was very pleased to get ashore. It was he who gave HERMES the Crab title "RIRB" - Rat Infested Rust Bucket.
The Ship was, in fact, OK. But its management was lacking in very many ways. Thankfully for many, the magnificent Chinook "Bravo November" was not pushed off the back of HERMES into the sea - which was a very real threat - because the crew took the option of going ashore unsupported, which was the only alternative open to them following the demise of ATLANTIC CONVEYOR. And what a great job that one Chinook did!!
Yes, more thread drift, but the previous comment needs to be put into context.
Suspicion breeds confidence
BomberH
I seem to recall he was carrying BL755 at the time which were swiftly sent over the side. No harm done and a good result and a working aircraft for the next day.
I seem to recall he was carrying BL755 at the time which were swiftly sent over the side. No harm done and a good result and a working aircraft for the next day.
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glojo With the F-18 the FBW flight controls are designed to do the right thing on their own, so require that the pilot does not hold the stick during the cat stroke. The cat will not be fired unless the pilot's hand can be seen gripping the canopy grip as shown in the video. The salute comes first followed by gripping that handle.