Quote:BRAZILIAN navy ships are set to begin trawling for debris from the Air France passenger plane that crashed into the Atlantic.

The ships will try to recover pieces of the plane that were spotted by search aircraft a day earlier.

Brazil's government has discounted the idea of a mid-air explosion bringing down the plane, which was carrying 228 people from Rio de Janeiro to Paris when it met its fate early Monday.

No distress call was received from the pilots.

Defence Minister Nelson Jobim said a 20km long fuel slick sighted in the crash zone "means that it is improbable that there was a fire or explosion" because the high-octane jet fuel would otherwise have been ignited.

But he cautioned that that was "just a hypothesis" and stressed that the mystery of Air France flight AF 477 was far from being solved.

Answers may lie in the plane's black box data and cockpit voice recorders.

But they are likely resting on the rugged sea bottom, at least 3000m underwater, and would be very difficult if not impossible to recover even if the 200km wide search area were narrowed down, experts said.

"It's equivalent to looking for a needle in a haystack," Pierre Cochonat, of the French marine research institute Ifremer, said.

Two Brazilian navy vessels, a patrol boat and a corvette, were in the area, 1000km off Brazil's northeast coast, officials said.

No bodies have yet been spotted.

Three other Brazilian vessels, including a tanker able to keep the flotilla in the area for weeks, and a French ship with mini-submarines will arrive over coming days.

A few of the relatives of those on board the Air France Airbus A330 told media they still held out hope their loved ones might have survived. But many others were resigned to their loved one's deaths.

If final confirmation comes that all those on board the Air France plane perished, it would be the worst disaster for the French airline in its 70-year history.

It would also be the worst civil aviation accident since 2001, when an American Airlines Airbus A300 crashed in New York, killing all 260 people on board.

Source: Agence France Presse June 04, 2009

What amazes me is that ships, boats and light aircraft must be fitted with EPIRBs (Emergency Position Indicating Radio Beacons) but large commercial aircraft are not equipped with them. In the case of an accident they are designed to float in the water to optimize the signal to the satellite and to assists rescue authorities in their search to locate those in distress. If an EPIRB had been fitted to AF477, 3 days would not have been lost just to find the crash site

Quote:Deep-sea challenge of Air France debris

The remains of the Air France jet which went missing over the Atlantic on Monday are in very deep water, making the job of finding them extremely difficult, not to mention any attempt to salvage the aircraft and the bodies of those who were on board.

A French government minister has said the black box flight recorders are believed to be at a depth of between 3,660m (12,000 ft) and 3,700m. At this depth, pressure is immense and there is no daylight.

Any search to locate the flight recorders and any plane wreckage will involve a number of technologies. Below we outline the main methods of salvaging wrecks, from divers to the latest deep sea exploratory vehicles.

Scuba diver: US Navy divers were used to retrieve bodies and light debris from TWA flight 800 which crashed into the Atlantic off New York in 1996. The plane was discovered at a depth of 40m, within the maximum operating depth for divers which is typically 50m.

Bathymetric survey: This is a sonar device placed beneath a ship that would sail in a designated pattern over an area to map the seabed. It "looks" straight down to produce a 3-D map of the seabed but can only operate up to a depth of 1,000m.

Pinger Locator System: This is a specialised listening device that is towed at a depth of up to 4,000m by a ship. The device listens out for the sound of the pinger which is part of the flight recorder. It is activated on contact with sea water and every commercial aircraft carries one. It will emit a signal for up to 30 days.

Side Scan Sonar: Once the pinger is located, a more detailed survey of the area can be carried out. The SSS is a cigar-shaped tube that is towed by a ship to map the seabed in a designated pattern. "You attach it to a cable and you mow the lawn," says Tim Janaitis, Director of Business Development at Phoenix International, a specialist marine salvage company. Mr Janaitis said he believed only the US Navy had the sophisticated pinger locator system to operate at the depth the Air France aeroplane is believed to be.

Remote Operated Vehicle: These are highly sophisticated yet robust underwater vehicles that can operate at depths up to 6,000m. They have video and powerful lights to illuminate the gloomy deep waters that they operate in. They can also have mechanical arms attached that allow the ROV to pick up bits of debris or attach straps to enable a ship's winch to lift the item to the surface. Phoenix International says it has raised a portion of an Israeli submarine weighing 3,600kg from a depth of 3,000m. The US navy has raised an entire helicopter from a depth of 6,000m.

Mini submarine: France has dispatched a boat with a mini-submarine, the Nautile, aboard. This can operate at a depth of 6,000m, but it was not expected to reach the zone until early next week.

Source: BBC 3 June 2009

Air France Flight 447 'may have stalled after pilot error'

The Air France jet that crashed into the Atlantic killing 228 may have stalled after pilots slowed down too much as they encountered turbulence, new information suggests.

Airbus is to send advice on flying in storms to operators of its A330 jets, Le Monde reported today. It would remind crews of the need to maintain adequate thrust from the engines and the correct attitude, or angle of flight, when entering heavy turbulence.

Pilots slow down aircraft when entering stormy zones of the type encountered by Air France Flight 447 early on Monday as it was flying from Rio to Paris. The fact that the manufacturer of the aircraft is issuing new advice indicates that investigators have evidence that the aircraft slowed down too much, causing a high-altitude aerodynamic stall. This would explain why the aircraft apparently broke up at altitude over the Atlantic.

Airbus declined to comment on the report. A company official said: "Each time there is an accident, it is imperative for the manufacturer to inform all operators of the type of aircraft concerned of any specific procedures to put in place or any checks to carry out."

Timesonline