PDA

View Full Version : Difference between escape slide and life raft


IFLY_INDIGO
29th Nov 2016, 16:33
What are the exact differences between escape slide and life-raft? What are the regulations regarding their carriage on board?

Capt Scribble
29th Nov 2016, 16:40
A life raft is built more like a boat and has survival equipment on board. A slide merely allows you to exit the aircraft safely without steps but could be used as a flotation device for pax if necessary. The regs would probably depend upon your authority but may be stipulated by the international authority.

RAT 5
30th Nov 2016, 11:57
There are escape slides, life rafts & slide rafts. The 1st, slide, is as per Scribble says. A life raft is an independent item stored on board and needs to be launched. A slide raft is an escape slide that can then be detached and can be used as a raft with much more protection for pax. In my day the large ETOPS a/c were fitted with slide rafts. Whether that was an XAA requirement or a manufacturer design I do not know, but the ETOPS regs must have come into play.

Metro man
30th Nov 2016, 14:11
The A320 has slide rafts on the main doors that are designed to carry passengers in the event of a water landing i.e. they float and detach from the aircraft. In the event of a land evacuation they function as slides. The overwing exit slides are not designed to float or be detached and normally would only be used for land evacuation.

Separate life rafts are also carried which need to be taken out of their compartments and manually launched.

Unlike the Titanic, there are more than enough places for everyone onboard and some overload capacity beyond the stated numbers is built in just incase.

Localiser Green
3rd Dec 2016, 16:47
The overwing exit slides are not designed to float or be detached and normally would only be used for land evacuation.

In fact in a ditching the overwing exit slides will probably not even inflate, as the aspirators for the slides are located underneath the wing:

Off-wing escape slides are permanently armed and deploy and inflate automatically when one or both of the window exits on that side of the aircraft are opened, from the outside or the inside. The deployment and inflation sequence is achieved in approximately 5 seconds.

The aspirators that draw in ambient air to inflate the off-wing escape slide are located just below the wing. In a ditching, the off-wing escape slide should not inflate as these aspirators are likely to be under water.

In the unlikely event the off-wing escape slide does inflate, it can not be used as a raft or flotation device and can not be disconnected from the aircraft.

Interesting that in the US Airways Hudson River incident the overwing slides did achieve at least partial inflation. Does anyone know the exact location of the A320 overwing exit escape slide aspirators?

EcamSurprise
3rd Dec 2016, 20:25
The A320 has slide rafts on the main doors that are designed to carry passengers in the event of a water landing

This depends on the airline / operation.

Our A320s do NOT have rafts.

Metro man
4th Dec 2016, 03:02
Are they operated solely over land and do not venture out to sea ? Possibly a cost saving option for an airline where this is not needed.

In the Hudson River incident the ditching button wasn't pressed, would this have had any effect ?

Possibly some trapped air in the duct and the initial charge gave some degree of inflation ?

RAT 5
4th Dec 2016, 14:31
How is it on A320? In B737 it is not recommended to use the doors in a ditching, only over-wing hatches. Thus the pax are relying on life vests for buoyancy. Rafts were not carried as non-ETOPS, but ditching between STG & FNC or LIS & TFS it would be nice to have slide-rafts, but then you can't use the doors. It was always a circular discussion, during SEP recurrency, about shifting pax a little to raise one set of doors above the water line, inflate and detach the slides; even repeat the process for the other end as the pax made an 'orderly 'exit onto the wing and the not so inviting winter sea.
It would seem that the A320 on Hudson was hatches & life jackets only, by design.

triploss
4th Dec 2016, 18:26
I'm pretty sure United advise front doors + overwing exits for water landings on their 737s (during the SLF saftety briefing) - I'll be on one tomorrow so I can try to snap a picture of the safety card to verify too (they definitely advise against using the rear doors except when instructed by the crew). I don't think I've ever been on one without rafts, most of their 737s seem to be ETOPS regardless.

Can't remember what they advise on the A320 though, or what other airlines do on theirs.

FlightDetent
4th Dec 2016, 22:15
My understanding was that 737-400 and A320 do not require slide-rafts as per certification specification.

Different on -800 and A321. Indeed though, the Hudson A320 actually A/C had rafts, unlike most ours.

The "overwater" seems to relate to carriage of life vest as opposed to seatcushions only as flotation devices. IIRC Cactus had no life vests for PAX.

RAT 5
4th Dec 2016, 23:31
I'm pretty sure United advise front doors + overwing exits for water landings on their 737s
As the pax surge forward would that not put the L1 door sill under water?

EcamSurprise
5th Dec 2016, 00:01
Rafts were not carried as non-ETOPS, but ditching between STG & FNC or LIS & TFS it would be nice to have slide-rafts,

It would certainly be a comfier feeling to have rafts on those routes.

triploss
9th Dec 2016, 07:18
As the pax surge forward would that not put the L1 door sill under water?
It's not like passengers pay attention to the safety briefing anyway.

Reporting back from my United ETOPS 739ER ride: I blanked out during the part of the safety briefing describing doors, so I can't describe what they said (yes, really...).

From the safety card:

Land based evacuation:
- All 4 doors, equipped with slides
- And 4 overwing exits (climbing down/sliding over the rear of the wing)

Water based evacuation:
- Front doors (1L/R), NO sliderafts, entering directly into inflated liferafts (2 liferafts located above the front cabin)
- Overwing exits, entering directly into inflated liferafts, over the front of the wing (2 liferafts located in roof of the middle/back of the cabin)
(No use of rear doors)

Metro man
9th Dec 2016, 11:54
With safety briefings:

Half don't listen.
Of the half that do listen, half don't understand.
Of those that understand, half won't remember.

This leaves a small number who would probably be able to work it out by themselves anyway.

IFLY_INDIGO
14th Dec 2016, 02:21
We need lifesaving rafts if the distance to land while flying over water is more than 400 nm at any point of time during the flight.