[condor]

@Gannu, it may be pressurized & air-tight. But it's heavier than water, isnt it ? How long before it sinks, will depend on how hard the landing was.

[H_Dogg72]

This is turning out to be just like the air France case, A 2 year long search to find the cause.

I hope they find something.
It was pointed out earlier that moving to the Indian Ocean was like going from a chessboard to a football field.

[aah78]

Originally Posted by Gannu_1

But if the aircraft hasn't broken upon impact, wouldn't the buoyancy keep it afloat like a ship and not sink?

If I'm not mistaken, in an airplane, the cabin is pressurized only as long as the engines are running.

Also, the cargo hold can only be buoyant for a limited time as the landing gear section is not completely air tight.
Plus, the different compartments can't be sealed off from each other, as they can be in a ship, in case of flooding.

[Soumyajit9]

Just came across this post and a video which has been trending over Facebook.
I'm not sure, if its' a real footage from the Indian Ocean, or someone posted a random video saying that this is Indian Ocean.
If this is true, then I have almost zero hopes of finding the plane.
The search was suspended due to bad weather. I am not remotely associated with sailors, but this Ocean looks very nasty in bad weather.
A big round of applause for the SAR team, braving the odds to find the plane.

http://www.storypick.com/4-minute-vi...-indian-ocean/

http://www.youtube.com/watch?v=imqW_g-5S0I

[Jeroen]

Here you will find what I think is the most comprehensive and factual write up to date:

http://avherald.com/h?article=4710c69b

Scroll down to the large updated bit in yellow and you will find some more details on these advanced calculation they have done. Further down some more graphics on the calculations, doppler effect etc.

Jeroen

[condor]

Originally Posted by aah78

If I'm not mistaken, in an airplane, the cabin is pressurized only as long as the engines are running.

Also, the cargo hold can only be buoyant for a limited time as the landing gear section is not completely air tight.
Plus, the different compartments can't be sealed off from each other, as they can be in a ship, in case of flooding.

@Aah78, the cargo hold would also be pressurised, but not heated. Maintaining pressure will mean that the compartment is air-tight. The hold would not be connected to the landing gear compartment - and two of those would any way be in the wings while the cargo is in the under-belly.

Your first point about pressurizing only till engines are running would be important.


Looking at the graphics in the post by Soumyajit, the indicated depth of the plane looks to be within the max depth that the American ship can search for. So there is a small chance that the black box may be located.

[Jeroen]

Originally Posted by condor

@Aah78, the cargo hold would also be pressurised, but not heated. Maintaining pressure will mean that the compartment is air-tight. The hold would not be connected to the landing gear compartment - and two of those would any way be in the wings while the cargo is in the under-belly.

Your first point about pressurizing only till engines are running would be important.


Looking at the graphics in the post by Soumyajit, the indicated depth of the plane looks to be within the max depth that the American ship can search for. So there is a small chance that the black box may be located.

Just because something is pressurized doesn't mean its airtight. Cabin pressure on planes such as the 777 is being regulated by allowing air in and regulating the outflow by means of automatic outflow valves. So there are all sort of openings in the hull to let air in and let air out. Would get very uncomfortable if that would not be the case. In fact everybody would die as you use up oxygen. Actually you need a lot of air moving through the cabin to keep temperature, humidity and oxygen at comfortable levels.

When a plane is very low, such as just prior hitting the water the outflow valves would be fully open.
Im no expert on this, but I would think that planes get most of their buoyancy from their wings rather then from their cabin/hold. Also, there are likely to be a lot of places where air is trapped between various parts of the plane. E.g. Between the outer skin and the pressure hull, wheel wells etc.

But eventually that air start escaping and the plane is likely to sink. As I pointed out before, ditching is a possibility. But a successful ditching in an ocean at night would be very difficult to say the least. With the latest information it might have been early morning and maybe some sun light already. Still, a trickt manoevre on an ocean with waves at the best of times.

Jeroen

[condor]

@Jeroen, some interesting points there. Thanks for that.

Originally Posted by Jeroen

Im no expert on this, but I would think that planes get most of their buoyancy from their wings rather then from their cabin/hold.

This is the only point I would like to add to. The wings are what hold the fuselage up in the air. The wings hold the engines which provide the power for the flight, and the wings also contain the flaps that help in ascent & descent. The fuselage is actually the load.

[Gannu_1]

Originally Posted by condor

The wings are what hold the fuselage up in the air. The wings hold the engines which provide the power for the flight, and the wings also contain the flaps that help in ascent & descent.

The fuel tanks are also located in the wings of the crafts.

The fuel might have been consumed completely before the plane descended else the slick would have come up on the surface of the waters. An oil slick is quickly noticed by the surveillance teams I understand.

[condor]

@Gannu, yes. I had mentioned that in my earlier post.

However, I am trying to find out / understand, how quickly / harshly will a commercial aircraft like this descend, when the fuel is exhausted and the engines are no longer running.

[anujmishra]

Originally Posted by condor

However, I am trying to find out / understand, how quickly / harshly will a commercial aircraft like this descend, when the fuel is exhausted and the engines are no longer running.

It depends upon situation to situation. I can recall two examples when engine stopped working. First one is Helios Air crash in 2005. Once engines smokef off due to fuel exhaustion, it was in air for less than 10 minutes only and crashed.

Other is US Airway flight 1549 where Pilot safely glided plane to Hudson river. In this case again it is less than 10 minutes.

[condor]

Yes, Anuj. No specifics to that. Could also depend on weather ?

I was trying to understand the result of combination like cruising altitude, speed at the time fuel ran out, rate of drop, horizontal distance to touch-down/ contact with water, angle of contact ....

[sandeepmdas]

Originally Posted by anujmishra

It depends upon situation to situation. I can recall two examples when engine stopped working.

There's another example - with a happy ending: the Gimli Glider.

The Gimli Glider is the nickname of an Air Canada aircraft that was involved in an unusual aviation incident. A Boeing 767-233 jet, ran out of fuel at an altitude of 41,000 feet (12,000 m), about halfway through its flight originating in Montreal to Edmonton. The crew were able to glide the aircraft safely to an emergency landing at Gimli Industrial Park Airport.

Read how they managed it:
http://en.wikipedia.org/wiki/Gimli_Glider

[saket77]

Originally Posted by sandeepmdas

There's another example - with a happy ending: the Gimli Glider.

The Gimli Glider is the nickname of an Air Canada aircraft that was involved in an unusual aviation incident. A Boeing 767-233 jet, ran out of fuel at an altitude of 41,000 feet (12,000 m), about halfway through its flight originating in Montreal to Edmonton. The crew were able to glide the aircraft safely to an emergency landing at Gimli Industrial Park Airport.

Read how they managed it:
http://en.wikipedia.org/wiki/Gimli_Glider

There is an Air crash investigation episode too on that incident; which incidentally, I was watching 2 days ago. The first (L) engine starved at the height of 41K feet while the right engine probably went off at 26K feet. The aircraft managed quite some distance without fuel. The skilled pilots were able to 'slip' it and they managed to get it down safely on a decommissioned runway, albeit with some drama with the nose gear.

However, Malaysia still, I believe has to provide details & proof of the crash. Till now, it is only a settlement with the current situation, not the resolution.

[audioholic]

Originally Posted by anujmishra

It depends upon situation to situation. I can recall two examples when engine stopped working. First one is Helios Air crash in 2005. Once engines smokef off due to fuel exhaustion, it was in air for less than 10 minutes only and crashed.

Other is US Airway flight 1549 where Pilot safely glided plane to Hudson river. In this case again it is less than 10 minutes.

The US airways flight was still at a low altitude when the engines failed. Yet it could glide for a few minutes. Hence I think that a flight in its cruising altitude Can glide for a longer period of time.