Disarming doors before ditching
Thread Starter
Disarming doors before ditching
On Sunday, I managed to follow the pool training session of a European airline. The trainer stated that as part of the ditching preparation doors should be on the un-armed position (the type under consideration was the 733/4).
My question is why the door should be un-armed? My understanding from reading the safety card is that the door can be used as a flotation device. So it is useful to have the slide armed.
Is there something I don't see here?
Rwy in Sight
My question is why the door should be un-armed? My understanding from reading the safety card is that the door can be used as a flotation device. So it is useful to have the slide armed.
Is there something I don't see here?
Rwy in Sight
In my experience, the reason we were given in training as to why in a ditching the doors should be put to manual/disarmed, is the door would more than likely (assuming the plane was level in the water) be below the water level, and the slide would ingest water and block the exit.
Our procedures were to use the overwing exits and chuck the life rafts out through them, before using the doors. The doors were supposed to be a last resort.
Our procedures were to use the overwing exits and chuck the life rafts out through them, before using the doors. The doors were supposed to be a last resort.
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It's a bit hypothetical since no-one has ever managed successfully to ditch an under-wing-engined passenger aircraft in open water.
(People got out of the Comoros one after it broke up on impact; where the doors/slides were wouldn't have made any significant difference, and the Indonesian one was more treating a shallow river as a wet runway rather than a ditching.)
(People got out of the Comoros one after it broke up on impact; where the doors/slides were wouldn't have made any significant difference, and the Indonesian one was more treating a shallow river as a wet runway rather than a ditching.)
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Answer is because some airlines will use liferafts from the primary exits on 737s. As these aircraft are not fitted with duel use 'sliderafts' (like A320, 747 etc) the slides are not used as they would get in the way of attaching and launching the rafts, which need to be brought to the door from overhead stowages.
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Inflatables float.
Slides are inflatable.
Open a door level with or below the waterline and the slide will float on the water as soon as it hit the water, ie, right by the door.
Inflating a slide at this water level pushes the slide either inwards to the cabin or upwards to the sky, blocking the exit.
Doors should only be opened in automatic if the door is above the waterline.
Your aircraft type and average aircraft weight (does your airline carry cargo, etc), will determine whther your policy is to have arms disarmed or armed in a ditching.
A B737 will usually use the overwing exits with the door slides as flotation devices only because the wings are higher than the doors and designed to float above water, also you can fit all passengers onto the wings. A B747 however has a higher centre of gravity for flotation and it is likely if the aircraft is in tact on ditching that majority of doors are above water. Sliderafts are used because the wings wouldnt accomodate all passengers and because it is more likely that you are further away from immediate assistance and may need to break or move away from the aircraft for survival.
The CAA in the UK for example, agree with the airline their policies and then publish that ruling/ agreement as an operating procedure and official drill for that airline.
However, with any emergency, you will use your instinct, skill and judgement on the day to maximise survival.
Check for hazards........etc
Slides are inflatable.
Open a door level with or below the waterline and the slide will float on the water as soon as it hit the water, ie, right by the door.
Inflating a slide at this water level pushes the slide either inwards to the cabin or upwards to the sky, blocking the exit.
Doors should only be opened in automatic if the door is above the waterline.
Your aircraft type and average aircraft weight (does your airline carry cargo, etc), will determine whther your policy is to have arms disarmed or armed in a ditching.
A B737 will usually use the overwing exits with the door slides as flotation devices only because the wings are higher than the doors and designed to float above water, also you can fit all passengers onto the wings. A B747 however has a higher centre of gravity for flotation and it is likely if the aircraft is in tact on ditching that majority of doors are above water. Sliderafts are used because the wings wouldnt accomodate all passengers and because it is more likely that you are further away from immediate assistance and may need to break or move away from the aircraft for survival.
The CAA in the UK for example, agree with the airline their policies and then publish that ruling/ agreement as an operating procedure and official drill for that airline.
However, with any emergency, you will use your instinct, skill and judgement on the day to maximise survival.
Check for hazards........etc
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As already mentioned in a variety of ways:
737s use slides and liferafts. Most liferafts are kept in dedicated overhead storage or overhead lockers.
Other airplanes use sliderafts.
The door can be opened armed, and then the slide detached, and if necessary used for floatation.
The procedure is not to, because as some have mentioned it may block the door (possible, but unlikely), most slides/slide rafts use air aspirators to inflate (not sure if 737 slide does) and water ingestion will pump water inside the slide if the aspirators are submerged, it is not designed for survival at sea, its not very big and probably wouldnt be able to remain stable/upright with more than a couple of people on it.
The dedicated raft has sea anchors, some survival gear, stability, a cover for shelter, and some alerting gear, the slide has none of these.
737s use slides and liferafts. Most liferafts are kept in dedicated overhead storage or overhead lockers.
Other airplanes use sliderafts.
The door can be opened armed, and then the slide detached, and if necessary used for floatation.
The procedure is not to, because as some have mentioned it may block the door (possible, but unlikely), most slides/slide rafts use air aspirators to inflate (not sure if 737 slide does) and water ingestion will pump water inside the slide if the aspirators are submerged, it is not designed for survival at sea, its not very big and probably wouldnt be able to remain stable/upright with more than a couple of people on it.
The dedicated raft has sea anchors, some survival gear, stability, a cover for shelter, and some alerting gear, the slide has none of these.
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The 737 is a funny aircraft. I love working on it, but it is indeed a funny one.
It is not as high as other SH aircraft (like the A320 family for example), was made like that to be "easier" to turn around and for other technical reasons. If you look at it you can see that its engines had to be "onion-shaped" (flat at the bottom) because it sits so close to the ground.(series -300/400/500 and NG)
It has been noticed than in a ditching it is likely that the water level would be above the door sill hence making these exits unusable for two reasons:
1) the slide has to drop a certain height before it can successfully deploy
(I once witnessed an armed door being accidentally opened and since the stairs were in place the bustle opened up but thank god the slide didn't have far to go as it just fell onto the top of the stairs, and there it rested till engineers could make the door serviceable again)
2) On ANY aircraft, if you open a door when the water level is not safe (for example because of the attitude of the aircraft) it is a big problem as the last thing you want is to have water come inside the aircraft when you're trying to get out!
That's why most 737 Operators's Ditching procedures require the crew to disengage the slides and brief the passengers accordingly as part of the cabin preparations and re-direct passengers to the OW exits. That's where they/we would stay till the rescue services arrive.
To clarify most operator's 737 slides are slides/flotation devices and not slide/rafts i.e. the slide can be detatched and used as a flotation aid but can't cope with big weights for long periods of time (pax cannot board it and use it as shelter like the slide/raft). BA doesn't have any life rafts (those stored in the ceiling or OH lockers as blueloo has explained) on board either as we don't have flights where we cross big waters, but I am pretty sure that other airlines have them. Believe it or not the 737 was the very first ETOPS aircraft!!!
So....that's what we should do in a planned ditching. On the other hand in an unplanned ditching it's up to you and the specific situation and what you can actually do on the day....I personally think I'd meditate on converting to some powerful religion and start praying really hard!!!
FBWxxx
It is not as high as other SH aircraft (like the A320 family for example), was made like that to be "easier" to turn around and for other technical reasons. If you look at it you can see that its engines had to be "onion-shaped" (flat at the bottom) because it sits so close to the ground.(series -300/400/500 and NG)
It has been noticed than in a ditching it is likely that the water level would be above the door sill hence making these exits unusable for two reasons:
1) the slide has to drop a certain height before it can successfully deploy
(I once witnessed an armed door being accidentally opened and since the stairs were in place the bustle opened up but thank god the slide didn't have far to go as it just fell onto the top of the stairs, and there it rested till engineers could make the door serviceable again)
2) On ANY aircraft, if you open a door when the water level is not safe (for example because of the attitude of the aircraft) it is a big problem as the last thing you want is to have water come inside the aircraft when you're trying to get out!
That's why most 737 Operators's Ditching procedures require the crew to disengage the slides and brief the passengers accordingly as part of the cabin preparations and re-direct passengers to the OW exits. That's where they/we would stay till the rescue services arrive.
To clarify most operator's 737 slides are slides/flotation devices and not slide/rafts i.e. the slide can be detatched and used as a flotation aid but can't cope with big weights for long periods of time (pax cannot board it and use it as shelter like the slide/raft). BA doesn't have any life rafts (those stored in the ceiling or OH lockers as blueloo has explained) on board either as we don't have flights where we cross big waters, but I am pretty sure that other airlines have them. Believe it or not the 737 was the very first ETOPS aircraft!!!
So....that's what we should do in a planned ditching. On the other hand in an unplanned ditching it's up to you and the specific situation and what you can actually do on the day....I personally think I'd meditate on converting to some powerful religion and start praying really hard!!!
FBWxxx
Last edited by flybywire; 3rd Jul 2006 at 18:02.
Thread Starter
Thanks a lot for your answers.
However the instruction described the slide as a flotation device. The follow up question then is how do you put it in the water to be used as such? At the end of the session they put the raft in the pool and practice (if I understand well) to take hold from the raft.
By the way the slide the did blow had an aspirator.
Rwy in Sight
PS It was a lovely Sunday only if they let me dive in the pool having put on a life jacket!
However the instruction described the slide as a flotation device. The follow up question then is how do you put it in the water to be used as such? At the end of the session they put the raft in the pool and practice (if I understand well) to take hold from the raft.
By the way the slide the did blow had an aspirator.
Rwy in Sight
PS It was a lovely Sunday only if they let me dive in the pool having put on a life jacket!
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well ideally you'd be able to open the door, deploy the slide and then detatch it by pulling a grey handle that is underneath a flap. Slides as you said are only floatation devices and not slide/rafts, so they would help but are not "essential" (if you can use this word in a ditching!).
However even if the water line were below the door sill, the priority would still be to get the pax on the wings and ask them to sit closely together (one behind the other) to maximise the space and keep their body warmth. Unless "absolutely necessary" (for example if the plane starts to sink) pocedures advise us to keep them as "dry" as practically possible while waiting to be rescued. If the doors can be used then we would engage the girt bar, open the door, inflate the slide/flotation device and then separate it and use it but, as I said before, the OW exits would still remain our primary escape route. We do need to know how to use the slides hence the need of a practical training in a swimming pool. (great fun, I remember!)
I know it can all sound a bit confusing and way too minimalist, but let's remember that the 737 is a short-haul aircraft with an autonomy of <5 hours on full load (I'm thinking of the 400 at the moment) and that is rarely used on transatlantic routes. Those airlines that do use them on such routes have special equipment on board (like some BBJ for example) and very rarely carry 180 people!!!!!
As I said before given the routes operated by this aircraft Ideally the rescue services would reach the poor old 737 quicker than if it happened to a 777 in the middle of the ocean!!
Though the hard work is to make sure it will never happen!! 
FBW
However even if the water line were below the door sill, the priority would still be to get the pax on the wings and ask them to sit closely together (one behind the other) to maximise the space and keep their body warmth. Unless "absolutely necessary" (for example if the plane starts to sink) pocedures advise us to keep them as "dry" as practically possible while waiting to be rescued. If the doors can be used then we would engage the girt bar, open the door, inflate the slide/flotation device and then separate it and use it but, as I said before, the OW exits would still remain our primary escape route. We do need to know how to use the slides hence the need of a practical training in a swimming pool. (great fun, I remember!)
I know it can all sound a bit confusing and way too minimalist, but let's remember that the 737 is a short-haul aircraft with an autonomy of <5 hours on full load (I'm thinking of the 400 at the moment) and that is rarely used on transatlantic routes. Those airlines that do use them on such routes have special equipment on board (like some BBJ for example) and very rarely carry 180 people!!!!!
As I said before given the routes operated by this aircraft Ideally the rescue services would reach the poor old 737 quicker than if it happened to a 777 in the middle of the ocean!!
Though the hard work is to make sure it will never happen!!
FBW
Last edited by flybywire; 3rd Jul 2006 at 20:44.
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Just to add to the information already given here.
The 737 is tail heavy and the rear doors would definately be submerged in a ditching. However the forward doors should be above the water line and you could use the slides as floatation aids. (assuming that you ditch on a perfect day where the water is as flat as a millpond!), Thats the SEP from my company anyway.
6
The 737 is tail heavy and the rear doors would definately be submerged in a ditching. However the forward doors should be above the water line and you could use the slides as floatation aids. (assuming that you ditch on a perfect day where the water is as flat as a millpond!), Thats the SEP from my company anyway.
6
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Originally Posted by flybywire
well ideally you'd be able to open the door, deploy the slide and then detatch it by pulling a grey handle that is underneath a flap. Slides as you said are only floatation devices and not slide/rafts, so they would help but are not "essential" (if you can use this word in a ditching!).
However even if the water line were below the door sill, the priority would still be to get the pax on the wings and ask them to sit closely together (one behind the other) to maximise the space and keep their body warmth. Unless "absolutely necessary" (for example if the plane starts to sink) pocedures advise us to keep them as "dry" as practically possible while waiting to be rescued. If the doors can be used then we would engage the girt bar, open the door, inflate the slide/flotation device and then separate it and use it but, as I said before, the OW exits would still remain our primary escape route. We do need to know how to use the slides hence the need of a practical training in a swimming pool. (great fun, I remember!)
I know it can all sound a bit confusing and way too minimalist, but let's remember that the 737 is a short-haul aircraft with an autonomy of <5 hours on full load (I'm thinking of the 400 at the moment) and that is rarely used on transatlantic routes. Those airlines that do use them on such routes have special equipment on board (like some BBJ for example) and very rarely carry 180 people!!!!!
As I said before given the routes operated by this aircraft Ideally the rescue services would reach the poor old 737 quicker than if it happened to a 777 in the middle of the ocean!!
Though the hard work is to make sure it will never happen!!
FBW
However even if the water line were below the door sill, the priority would still be to get the pax on the wings and ask them to sit closely together (one behind the other) to maximise the space and keep their body warmth. Unless "absolutely necessary" (for example if the plane starts to sink) pocedures advise us to keep them as "dry" as practically possible while waiting to be rescued. If the doors can be used then we would engage the girt bar, open the door, inflate the slide/flotation device and then separate it and use it but, as I said before, the OW exits would still remain our primary escape route. We do need to know how to use the slides hence the need of a practical training in a swimming pool. (great fun, I remember!)
I know it can all sound a bit confusing and way too minimalist, but let's remember that the 737 is a short-haul aircraft with an autonomy of <5 hours on full load (I'm thinking of the 400 at the moment) and that is rarely used on transatlantic routes. Those airlines that do use them on such routes have special equipment on board (like some BBJ for example) and very rarely carry 180 people!!!!!
As I said before given the routes operated by this aircraft Ideally the rescue services would reach the poor old 737 quicker than if it happened to a 777 in the middle of the ocean!!
Though the hard work is to make sure it will never happen!!
FBW
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The latter model, or larger varient 737s are tail heavy - ie 737-800s. THe rear doors are likely to be obstructed by water, and hence are not a primary means of escape in a ditching, and whilst the 733/4s more than likely to be tail heavy too, the rear doors on these models are a primary means of escape in a ditching.
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the instruction described the slide as a flotation device. The follow up question then is how do you put it in the water to be used as such?
The slide can be detatched for use as flotation on a B737 if the door is in manual and approached from the outside. Remove bustle cover move to one side and pull manual inflation handle, or grab the assistance of someone, float either side of the door and pull the girtbar down into the water. Just ensure everyone is clear of the area and on the wings first.
whilst the 733/4s more than likely to be tail heavy too, the rear doors on these models are a primary means of escape in a ditching.
Majority of airlines suggest overwing exits on a B737-xxx are primary evacuation or escape routes. I'm trying to think of one that doesnt....
On such a small aircraft, everyone moving down the ailse for the slides down at the back doors may make your aircraft tail heavy!! The wings are the centre of gravity on water on a B737.
Basic rule of thumb, if you have slideRAFTS attached to a door, it should be suitable for initial exit in a ditching (hazards permitting). If its not a raft, its designed not to be sat on, therefore designed not to have people leaving the aircraft on it. However if your SOPs say differently, stick with that as it would have been approved for your airline and tailored for the type of aircraft you have and the average weight distribution and trim for your daily operation.
Six
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Originally Posted by Rwy in Sight
as part of the ditching preparation doors should be on the un-armed position (the type under consideration was the 733/4).
My question is why the door should be un-armed? My understanding from reading the safety card is that the door can be used as a flotation device
My question is why the door should be un-armed? My understanding from reading the safety card is that the door can be used as a flotation device
The 737 is thought to sit tail-down in water, according to Boeing manuals. Would be a shame to open the rear doors and sink the thing even faster.
The door slide on the 737 is NOT a raft. You have to get the rafts out of the over-head lockers during the panic and mayhem as fat people are trying to save themselves.
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Sixmile....I totally agree and thank you!!! You just saved me a very long reply
MuttleyCrew...I am sure RWYinSight meant "door slide" and not "door" only
and you're indeed correct, the 737 slide is only a flotation device and not a slide/raft. the 737 doors are small and the slide bustle way too tiny for a proper (and big enough) raft to be installed in it.
Muschixxl thank you for your compliment
I worked on so many different types of aircraft but each time I really made a point to try and know it as much as possible, as at the end of the day that's where I spend most of my time...the aircraft soon feels like it's Home (although much dirtier and smellier)
FBW x
MuttleyCrew...I am sure RWYinSight meant "door slide" and not "door" only
and you're indeed correct, the 737 slide is only a flotation device and not a slide/raft. the 737 doors are small and the slide bustle way too tiny for a proper (and big enough) raft to be installed in it.Muschixxl thank you for your compliment
I worked on so many different types of aircraft but each time I really made a point to try and know it as much as possible, as at the end of the day that's where I spend most of my time...the aircraft soon feels like it's Home (although much dirtier and smellier) FBW x
Originally Posted by christep
It's a bit hypothetical since no-one has ever managed successfully to ditch an under-wing-engined passenger aircraft in open water.
The Comores accident was unfortunate because just as they were on final approach to the ditching at minimum speed one engine failed with fuel starvation and they got the wing down ditching seen on videos taken from the beach.
Although there is a perception of ditching being a mid-ocean thing the vast majority which have happened seem to have been very close to shore.
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The Comores accident was unfortunate because just as they were on final approach to the ditching at minimum speed one engine failed with fuel starvation and they got the wing down ditching seen on videos taken from the beach.
The latter model, or larger varient 737s are tail heavy - ie 737-800s. THe rear doors are likely to be obstructed by water,
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Originally Posted by WHBM
Not so. Japan Air Lines put a DC-8 into San Francisco Bay about 2 miles before the runway when on final approach in poor (I presume !) visibility. I believe they used the rafts in a fully textbook manner. Amazingly the aircraft was recovered, fully overhauled and flew again. There used to be a picture on airliners.net of it being recovered by barge to the United maintenance base at SFO alongside the bay but it has gone.
The Comores accident was unfortunate because just as they were on final approach to the ditching at minimum speed one engine failed with fuel starvation and they got the wing down ditching seen on videos taken from the beach.
Although there is a perception of ditching being a mid-ocean thing the vast majority which have happened seem to have been very close to shore.
The Comores accident was unfortunate because just as they were on final approach to the ditching at minimum speed one engine failed with fuel starvation and they got the wing down ditching seen on videos taken from the beach.
Although there is a perception of ditching being a mid-ocean thing the vast majority which have happened seem to have been very close to shore.
The 1996 Comores accident was the one that involved an Ethiopian 767-200 flying from Addis Ababa to Nairobi. There were people on the beach who filmed the attempted ditching as it only happened some 500m from the sea shore! There were about 200 people on board including the crew and at least 2/3 of them didn't survive. I remember watching the video during my very first initial CRM course and you could clearly spot rows of seats being thrown out of the aircraft into the air....it was very scaring and one person resigned straight after seeing it (oh dear!
)All in all that ditching was a "success" as some 50 odd people survived it, and as WHBM said the hijacked aircraft was running out of fuel so I think the pilots did a very good job given the circumstances.
I never heard the version of the captain being hit on the head on landing... though from now on I'll have to do some proper investigation every time we get a bit of an "arrival"...
FBW
PS: 6chimes you are correct I have had a look in the 737-300/400/500 systems manual and they are too tail-heavy.
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The Ethiopian was being beaten with a fire extinguisher. A subtle difference...
The hammer tale took place on a freighter in the USA where a staff member took to the 3 crew-members with a claw-hammer.
The hammer tale took place on a freighter in the USA where a staff member took to the 3 crew-members with a claw-hammer.