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Airbus Ditching Button

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Airbus Ditching Button

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Old 16th Jan 2009, 03:23
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Airbus Ditching Button

The "DITCHING" button on Airbus aircraft has been mentioned several times in the wake of US1549. I'm aware of its existence but not its function(s?). Could some of you 'bus drivers shed some light on what happens when this button is pushed? Is it likely that it would still work on RAT/battery power only?
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Old 16th Jan 2009, 03:57
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According to the FCOM (A318/A319/A320/A321 FCOM 1.21.20 P7):

To prepare for ditching, the flight crew must press the DITCHING pushbutton on the CABIN PRESS control panel to close the outflow valve, the emergency ram air inlet, the avionics ventilation inlet and extract valves, and the pack flow control valves.
It seems that it certainly will work on BAT/RAT power only as it is prescribed in the QRH to be used in cases of ENG DUAL FAILURE, such as this case.

Tim
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Old 16th Jan 2009, 17:26
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The "DITCHING" button on Airbus aircraft has been mentioned several times in the wake of US1549. I'm aware of its existence but not its function(s?). Could some of you 'bus drivers shed some light on what happens when this button is pushed? Is it likely that it would still work on RAT/battery power only?
It will seal the ship in case of a water landing, and yes it will work on batt/rat power.
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Old 16th Jan 2009, 18:10
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I know the same switch will keep a MD-11 at a slight pre-press when pushed.
Approx 250 ft below ambient if memory serves me correctly.
This to keep doorseals and the like positively seated during the ditching itsself.

Does it do the same for an Airbus?

Keeping the fuselage slightly pressurized will also add a degree of stiffness, increasing the fuselage's rigitity.
Although I am unsure how much is to be gained from so slight a pressure.
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Old 17th Jan 2009, 06:24
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A little cabin pressure remaining can be a good and a bad thing, good to keep out the wet stuff but not good if you can't open the doors !
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Old 17th Jan 2009, 19:33
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Just some info for ye.

the aircraft would probably been in ditching(landing on water) config meaning that it stayed a float a lot longer than if it had not been.
When the pushbutton switch 13HL is pushed (the ON legend comes on) and the aircraft goes into the ditching configuration. This closes:
.the outflow valve 10HL,
.the pack flow control valves of the flow control units 23HB (24HB),
.the avionics skin air inlet valve 15HQ, if open,
.the avionics skin air outlet valve 22HQ, if open,
.the emergency ram-air inlet, if open,
.the fwd cargo isolation valves 4HN (5HN), if installed.
This basically would have prevented the cabin from flooding through the air conditioning and avionic cooling system
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Old 18th Jan 2009, 12:23
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Cabin Crew Alert

Seems they should add that to the switch. Some of the slf reported not knowing they were ditching..

GB
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Old 18th Jan 2009, 12:32
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I don't know if the A-320 doors are fitted with a door assist system when opening in emergency mode.
Having the cabin pressurized by 250 ft will not stop such a door assist system from opening the doors.

Ifix
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Old 18th Jan 2009, 16:26
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Yes, the A320 does have doors assist.

It was good to see in this incident that the engines detached on ditching, as they are designed to do. I have been told they would, this is the first case where they system has been tested.
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Old 18th Jan 2009, 17:06
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It was good to see in this incident that the engines detached on ditching, as they are designed to do.
As matter of fact the right engine is still attached, believe it or not. And the Ditching switch wasn't used.
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Old 18th Jan 2009, 17:07
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RH Engine did not detach

Pictures show RH engine still attached....still no pic from LH side of hoisted plane.
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Old 18th Jan 2009, 17:25
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Originally Posted by IFIX View Post
I don't know if the A-320 doors are fitted with a door assist system when opening in emergency mode.
yes they are.
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Old 24th Jan 2009, 05:57
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Forget, How did you find that the ditcvhing switch wasn't used? That is about the only thing on the ditching checklist that was really applicable in their situation. The plane seemed to float OK without it. Most of those holes would have been closed anyway.
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Old 24th Jan 2009, 07:55
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I thought I saw a pic showing considerable damage to the lower skins, and at least one cargo door bashed in. If that's the case, the Ditch Switch is a waste of time and circuitry.

The other possibility would be pressurizing the vessel as much as possible to counteract the implosion forces of hitting the water, as mentioned above. That would increase float time, too.

GB
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