Boeing 747-400 water landing evacuation procedure
 

Today I went on the Internet and I found this:

The link, if you care to click it, will take you straight to the 0:51 mark. What's interesting to me here is how the PA describes the evacuation procedure: "For passengers on the upper deck, if the water landing occurs, you should [go] downstairs and exit through main deck doors".

Two questions here. One, ARE THEY SERIOUS!? Is that a real evacuation procedure!? A layman passenger, in shock from water landing and possibly injured, should head down a darn steep flight of stairs (which may or may not still be there) to exit the plane!? Or is the water landing of such aircraft was considered so devastating that nobody was expected to survive anyway and this is just a keep-em-calm announcement?

And two, why are both wing and upper deck inflatable slides disabled in case of a water landing? What's the big difference? Beside faster evacuation, those large slides could be used as large rafts for passengers. Can the remaining eight hold ALL passengers of which there could be 660?

https://cimg9.ibsrv.net/gimg/pprune....0b0bdd18f3.jpg
As you can see doors 1,2,4 & 5 would result in slide-RAFTS that are basically flat (as seen door 1) the upper deck slide would result in slippery slide and swimming, if it’s cold you might be dead before you swam to a raft.

You are a bit late on the outrage bus since that slide configuration for the 744 has been around since the late 80s and AFAIK is industry wide for the machine.

It's been a while since I flew the QOTS but from memory I agree with the previous replies, ie..

The upper deck slides are not slide rafts because the position of the waterline post a ditching using an upper deck slide will mean any user gets dumped in the water at high speed..which has CCA has pointed out then leaves you very exposed.

Door 3 slides are not deployed in a ditching since when inflated the assembly would float aft at the inboard end of the wing trailing edge and would interfere with the sliderafts at Doors 4 (as bigduke6 explained...).

As a result the aircraft is equipped (as I recall it) with Dual lane sliderafts at Doors 1,2 4 and 5 only...oh, and FWIW the system and procedures have been "tested in the field"..

​​​​​China Airlines 605

"Immediately after the aircraft came to rest in the water, crew members ensured that all passengers donned life jackets and evacuated onto eight of the ten main deck emergency exits. These exits (as on all 747s) are equipped with inflatable evacuation slide/rafts for ditching emergencies. The passenger cabin remained completely above water during the evacuation,"

In the you-tube film above, the slats are retracted upon deployment of the thrust reversers, which makes sense. But when the TR are closed, the slats -while taxying- are deployed again. I'm not a pilot, but an engineer, so I've no idea why that is. Can anybody enlighten me? .

As I recall it ( with a "it's been ten years plus so health warning") the inboard/mid-span leading edges retract on selection of reverse to prevent them being damaged during reverse thrust operation ( ?FOD). Once reverse is cancelled the LEs should then automatically return to the position appropriate to the selected Flap setting..(and FWIW the slats work in harness/are controlled by the Flap setting/Flap lever, there's no separate slats control). Bearing that in mind..

1. On approach/touchdown with Flap selected the inboard/mid LEs will be "out".

2. On roll out with reverse selected the inboard/mid LEs will motor "in",

3. Once reverse is cancelled, usually towards the very end of the rollout, those LEs will then motor "out" again because usually at that point landing flap is still selected,

4. Once off the runway and when the after landing procedure is performed the flap is selected up and the LEs will motor "in" again..

That's the theory.....

Yessssss.....I sort of alluded to something like that being a possibility ;) :oh: in the original version of my post and then edited it out.....

744 Leading edge flaps (not slats)
 

More for LE flap panel fatigue life than FOD or structural interference, it seems.
Discussion here, see the last 2 posts from Cougar:
https://www.airlinepilotforums.com/a...p/t-64414.html
Which also covers the BA incident at JNB in 2009.
https://avherald.com/h?article=4198598d

MB

What the heck is a water landing? If it's happening on water, and not on land, it's not a landing.

Thanks Wiggy, that makes sense. But I also noticed that the outboard LE stays deployed when the TR is activated. Will that one not be FODded?

As I recall it I think FOD might have been just one of the reasons for the sequencing ( hence the "?" in front of my FOD comment) - the discussion in the link Minnie provided gives much more of the fine detail than I can remember....

Thanks for the info. And yes, you can (or rather, could) find 744 with that number of passengers. I clearly remember the number of passengers of the ill-fated JAL123 was 524. Japanese airlines easily max out Boeing 777 with 512 on JAL and 537 (I think) on ANA, so I suppose they did the same with 744.

Oh, hardly an outrage. Never flew it, never flew on it, and by the looks of it, the chances are slim for either of those activities. Just a bit surprised. Or maybe I should join the trend and be outraged about 748 grandfathered certification? Hmmm... Naaah.

Several versions of the B747SR were built for the Japan domestic market. Maximum seating was 490 - 560.

About the LED retraction during reverse thrust - it was really a legacy thing from when the hot stream reversers existed and all this hot air could blow on to the LEDs and entrain stuff to damage them. Fan reversers are actually in front of the LEDs close to their engines but why bugger around with certification stuff? Just leave well enough alone.

What about 747-400D? I vaguely remember reading about Boeing offering a configuration to sit 600+ passengers. Did any Japanese airline took it?

The 747-400D exit limit was 660 pax, but the only two operators of the variant (JAL and ANA, with 19 aircraft in total) flew them with 565 and 568 seats respectively.

I've seen Boeing docs showing a suggested 630-seat all-Y configuration.

Ah, that's where this number came from! Well, still, that's a lot of people for four rafts that don't look too big to me.