777's isn't going to 'hang on the props'(N1's).

Stall speed with almost zero fuel would have been in the 100-105 KIAS range.

a number of airplanes have been ditched largely intact.

I can think of a DC9 that sunk intact in the ocean and has never been recovered (5000' of water)

Other planes too.

I would say that an intact ditching is quite possible of this type of plane.

It is also possible that in a few minutes the plane sank, filled with water of course and not really crushed as both sides of the metal were equal pressure.

I think it is also possible the engines remained attached to the wings.

Just look up some historical ditchings. You have the internet to do it with.

100-105 with the engines shut down.

Now how about going very nose high at full thrust.
In this attitude a possible half the thrust is used to support the weight of the plane. In this attitude the plane would have more drag than any 777 has ever had before, even with wheels up.

Could a pilot drop it into the brine with almost no forward airspeed?


Forgive me but I'm processing this myself as I post. My prior thinking had it coming into heavy seas at night.

Power doesn't matter that much. Stall would be close to 100-105 KIAS.

Turn into the wind and ground speed (GS) would be 90-95 kts or less. Very survivable(see Ethiopian 767 hijack/ditching video which was at a much higher speed)

IMO if the plane had ditched, with empty tanks, it might have floated for hours. USAIR Hudson landing as an example.

But this is for a controlled ditching. There is no indication that this occurred.

misdagain

the USAIRways plane in the hudson had taken off less than 10 minutes prior to ditching. The tanks were far from empty. Although for a flight to KCLT they might not have been full either.

We have precious little data on controlled ditching of a jet airliner with high bypass wing mounted engines. Basically, the only 'good' data point is Sully's A320 on the Hudson. Ethiopian is not a good data point as the hijackers were reportedly fighting with the aircrew, trying to crash the airplane as they attempted to ditch. It's basically an unknown if it's possible to pull off what Sully did in a 777 in the open ocean.


Assuming a controlled ditching is possible with minimal airframe damage, the airframe could float a long time (after all, it's a lightweight structure that's designed to be airtight - Sully's A320 started sinking relatively quickly because they didn't have time to do the checklist which would have had them close the outflow valve). To sink, it would have been basically full of water and so it wouldn't implode as it sank.


That's all a long way of saying, assuming someone managed to pull off a 777 ditching with minimal damage, there would be minimal floating debris left behind.

MH 370
 

We should not forget that an Indonesia Garuda pilot ditched a 737 in a river largely intact in 2002

That is why I have been trying to determine what the lower end speed when it made contact with the water was (or might have been.)

With a plane empty of fuel we are told by 777 pilots that the stall speed would be 100-105 (IAS I assume.) Factor in a 20 knot headwind, that brings the speed on contact to 80-85.

Skully hit the Hudson at 137 and the plane stayed mostly intact.

Now factor in that MH370 may have been under control and with two functioning engines. Vectoring the thrust 45 degrees downward is certainly possible in a terminal touchdown. The power on stall speed must be at least 20 knots below power off stall speed.

I think that airframe engineer was figuring something closer to 200 knots at touchdown.

That airframe may be intact on the bottom, with little or no debris release. It is not at all unlikely that this is the case IMO.

Hardly; ............... not even close.

This ain't no Sukhoi SU30 or F-22 or Harrier with vectored thrust. We're talking about a big commercial airliner here. It doesn't have thrust vectoring and it sure as heck won't be controllable at 45 degrees angle of attack.

You don't happen to be a technical expert working for CNN, do you? :ugh:

@Mozella

You can vector thrust by increasing the angle of attack from level flight. There is a power off stall speed and there is a power on stall speed, with power on, the stall speed is lower because a portion of the thrust is being vectored down.

You claim to be a pilot, you should know that.

re: Thrust vectoring:
Strange term to use for a power on stall
Yeah but you do not want to impact with an extreme nose up attitude as you will smack the tail into the water which will probably break off the tail while slamming the nose into the water.
Slow as possible with a relatively level but nose up would be best methinks.

id
 

Ty Pontious,
May be some answers but not to my satisfaction.
As an ATCO of 33 years experience it was really a statement rather than a question!

Regards, Dave

Would this be a good time - if they haven't done it already - to lower a duplicate ULB (preferably with a dying battery) to the sea bed where they got the original readings?

Then, a) see if they can detect it, b) if they can, compare the readings and waterfall graph with the originals and c) check any signal deflection which they can then factor in to a new search area.

It would give them confidence (or not) to pursue the search in the current area.

Surveillance UAV used in search?
 

Maybe it was mentioned, but I could not find it anywhere: Was any Global Hawk type aircraft used in the search? Especially for the more westerly search areas it seems like the right craft to use. Instead of just one or two hours, these could stay in the search area for many hours, almost the entire daylight period.

Of course that would be a different way of searching, which implies flying a bit higher than normal search craft, and taking thousands of pictures downwards like a satellite. Those you can then analyze later after landing. But since the resolution and color quality would be much better than that of a satellite (you can adjust it by choosing flight altitude) much smaller items would be visible (satellites really would require an oil slick, or a floating part the size of the vertical fin a la AF447 to be successful). And therefore also the analysis of such images could probably be highly computerized.

But there was no mention of the US deploying one or two of theirs as far as I know (though they have flown in Australia before), and the Aussie units are not yet ready, correct?

Have you never seen photos of the aircraft after it was lifted from the Hudson? The lower rear fuselage showed major damage. Pressing the Ditching switch would not have helped very much.

There is no ditching switch on a 777.

Razak says preliminary report will be released next week.

Malaysia to release MH370 report, Prime Minister tells CNN - CNN.com

Well, it is not cloudy every day, and the search time is much longer per mission, so you will gain a lot even if just flying every other day. Plus, low level clouds, and clouds that it rains out of are a problem for regular search aircraft as well...

One day with a 12 hour "shift" in the search area is as much as 6 days with just two hours each for a regular search craft.

Plus the swath width can probably be larger. At these very low altitudes that regular SAR craft fly I think you cover not much more than half a mile either direction (looking for stuff the size of a flock of seat cushions, containers etc.), One mile at most. Consider also that a lot of objects like suitcases, composite components etc. (and bodies), will be mostly submerged, and therefore will be much, much easier to spot when looking straight down rather than at a shallow angle from a low flying craft.

So if the camera on a Global Hawk can take images fast enough and the harddisk is large enough, I think you could cover up to four miles swath width at a much more useful visual angle and very high resolution. From, say 10000 ft AGL. That would give up to 10 or even 20 times the area covered compared to a low flying search plane, per day! Plus the risk of an observer missing an object zooming by is much reduced if there is enough computer force / image analysts available.
(if lower res is enough, swath width can even be increased much more)

If there were a chance of metallic objects floating, the thing could even stay for the night time and during clouds, and radar search for >20 hours per mission, with possibly even larger swath width. But I am not sure if the RQ-4 radar would pick up an object such as a mostly submerged LD3 container. On top of the water definitely, but submerged, not sure.

Ditching in the open ocean would be a totally different prospect to the Hudson ditching. You would have to collide with the swell.

ULB Signal Transmission Test
 

HoldAtCharlie wrote
While it makes me fearful to see that idea published in the midst of a search (because of the confusion that it could cause), I admit that it could be useful if well thought out and monitored.