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More On The Air France Crash

The BBC reported that Bodies ‘found’ from missing plane

“We confirm the recovery from the water of debris and bodies from the Air France plane,” Col Amaral said at a news conference in the northern city of Recife.

He later added that two male bodies had been found, as well as objects linked to passengers known to be on the flight, including a suitcase with a plane ticket and a backpack with a computer inside.

The earlier report of finding wreckage had to be withdrawn when it was identified as probable trash from passing ships.

The CBC covers the more technical side of the incident: Air France jet sent 24 error messages

The Air France Airbus A-330 passenger jet that disappeared over the Atlantic Ocean this week sent 24 automated error messages in the final minutes of the flight, as one system after another shut down, French investigators said Saturday.

The French air accident investigation agency found that inconsistent airspeed readings by different instruments were issued as the crew struggled in a severe thunderstorm Monday on the flight from Rio de Janeiro to Paris.

One of the signals showed that the plane’s autopilot was either not working or was turned off by the pilot.

Investigators have also said the plane, which was carrying 228 people, lost cabin pressure and there was an electrical failure before the disaster. However, the pilots themselves sent no distress calls.

A lot of articles have mentioned the airspeed sensors which is a bit odd, as they are using pitot tubes which are one of the oldest instruments in aviation having been invented in the mid-19th century. The only known problem with them is icing and all modern versions have heaters to prevent that from happening. However, with the reports of multiple electrical failures, it is possible that the heater failed. As this is a “fly-by-wire” aircraft that was on auto-pilot at the beginning of their problems, a faulty airspeed sensor could cause a catastrophe change in actual airspeed.

The loss of cabin pressure can be the result of a bad seal, but it could also be the result of a lost window, or a crack in the skin of the aircraft. The fact that the pilots made no attempt to contact anyone is troubling, given the level of problems that were being reported automatically. It is possible that they encountered hail in the middle of the thunderstorms, and the flight deck was destroyed.

This is why the French have dispatched an advanced attack submarine to look for the data recorders. There are too many questions and not many answers contained in what we know for certain.


1 Badtux { 06.06.09 at 11:00 pm }

The plane would also lose cabin pressure if both engines went out because they ingested a huge amount of hail, because the cabin is pressurized by bleed air from the engines. The little turbine thingy to power the electrics would then drop — well, it’d drop if its door were not frozen shut — and the pilots would descend to a lower altitude while trying to do a restart, and if necessary, try to ditch — something which would *not* be successful on wind-tossed waves as it was on the smooth Hudson. If the little turbine thingy doesn’t drop the plane still has enough battery power to get down to low altitudes, but then has no choice but to ditch before the batteries die, because once the batteries die, that’s it on a fly-by-wire plane.

Regarding radio communications, that would drop out immediately upon the pilots attempting a descent to a lower altitude, because the frequencies used by aircraft are line-of-sight. They would have dropped below the radio horizon of the Cape Verde Islands swiftly. So if it went “WHAM!”, loss of cabin pressure, descent, then the co-pilot try to contact Momma, nope. Wouldn’t happen. So the black boxes are the last best hope to find out what actually happened. My suspicion is that we’ll find a dual-engine-out situation and an attempt to ditch, an attempt that was far less successful on the storm-tossed Atlantic than it was on the Hudson. At some point we have to re-think whether allowing twin-engined aircraft to fly long distances over the Atlantic is warranted… for many years it was illegal under European and U.S. laws (you needed at least three engines to fly over open ocean if you were going to land or take off from a European or U.S. airport) for safety reasons, and while a three or four-engined aircraft could have come to the same fate, that at least gave you one or two more chances of having an engine remaining after whamming into that cloud of hail…

Badtux´s last blog post..How to create a Charlie Manson

2 Bryan { 06.06.09 at 11:45 pm }

The airlines have their own freqs, which was how the data was being transmitted, and there is a “May Day” button which transmits position, altitude, and ID automatically on the guard frequencies, and probably to the ELT for the satellite. That’s why I wondered about flight deck damage.

The datalink should have reported engine shutdown and didn’t, but there were so many things going wrong, it may have lost the sensors.

Autopsies may supply more information, depending on the condition of the bodies, but finding the briefcase and the computer case along with the bodies and a seat, makes a failed ditching more likely.

Hopefully the sub’s sonar will locate the wreckage, so the submersibles can investigate and retrieve enough of it to make sense of what happened, even if they can’t locate the data recorders.

3 Badtux { 06.07.09 at 12:53 am }

Bryan, the frequencies involved are still line-of-sight, with the exception of the satellites, and the problem with the satellites is that they often don’t work under heavy cloud cover during cloudbursts (too much scatter from the rain droplets). It has been decades since aircraft were equipped with HF radio gear that could use tropospheric propagation, the notion nowdays is that there’s always a satellite or a ground station within line of sight so why bother?

One amateur radio operator recently asked to see the radio shack on a cruise liner to see what kind of radio gear they had. The first officer smiled, and said “You’ll be suprised.” They walked into a room that had… a personal computer. A regular old PC attached to a satellite modem. HF is dead in maritime and aviation, everybody assumes you can always get a satellite. Which is great, until you can’t…

– Badtux the Radio Penguin (licensed amateur radio operator :-).

Badtux´s last blog post..How to create a Charlie Manson

4 Bryan { 06.07.09 at 1:18 am }

There were at least three other aircraft in the same general area, and sending out a “May Day” is SOP on most flight decks. It is a two step process, like an arming switch it has a cover to prevent an accident, but they had three pilots on board.

We know they had a radio link because they had the data feed, and the loss of autopilot was late in the cycle of failures.

Without the “black boxes” [they’re actually international orange] we can’t know for sure what happened.

With 3,500 hours and more take-offs than landings, I’m familiar with the procedures and equipment. The French may have different protocols and SOPs, but they can’t be that different flying internationally. You don’t do things like that because you know they will work; you do them because they are part of the emergency procedures that you are trained for.