Safer skies
June 9, 2009
Air France has promised to update all of the speed sensors, known as pitot tubes, on its A330 and A340 aircraft by the end of the month. This comes after the French pilots' trade union Alter urged its members not to fly the planes until the upgrades were complete.
This crucial equipment monitors the airspeed of a plane by measuring air pressure, and the older version is considered prone to icing over, especially in bad weather.
French investigators are looking into the possibility that all three pitot tubes on flight AF447 iced up in a storm at high altitude, providing false airspeed data to the cockpit.
"The causes of the loss of the Air France flight are not official at the moment, we are not sure," Alter trade union representative and pilot Francois Hamant told Deusche Welle, "but we do believe it might be one of the main explanations of the loss of the aircraft, the icing of the three probes."
France's Transport Minister Dominique Bussereau told French radio that such a situation could have resulted in "two bad consequences for the survival of the plane".
"Too low a speed, which can cause it to stall, or too high a speed, which can lead to the plane ripping up as it approached the speed of sound, as the outer skin is not designed to resist such speed," he said.
Flying blind
Francois Hamant says that when flying in stormy weather - as flight AF447 was when it crashed into the Atlantic Ocean - a pilot is totally reliant on the plane's instruments.
"When you fly blind, sometimes you get dizzy by the weather conditions, physically dizzy, and you need your instruments not to feel dizzy anymore, to regain your orientation," he says. Without accurate feedback from equipment like pitot tubes, he says a pilot is lost.
"You lose all references, you don't know where you are, your position relative to the horizontal and vertical horizons. Without this information you lose orientation and it's impossible to recover because you don't know where you are."
The investigation into what caused the crash is ongoing, there is no proof that faulty pitot tubes were the cause of the incident. However, Hamant says his union felt that as the older model is known to be more prone to failure, it was imperative that the updates took place immediately, regardless of the outcome into a probe of the air disaster in which 228 people died.
"When it comes to safety, you need to improve all the time, and we feared that the length of the enquiries would be too long, we had to take decisions in the short term – with immediate effect."
Search continues
Recovery teams are still scouring the remote area of the Atlantic Ocean where the Air France carrier went down. They have discovered at least 28 bodies, people's personal belongings and a number of parts from the stricken airliner.
However, the all-important black boxes - which could hold clues to what caused the crash - have not yet been located.
The US is sending two listening devices to assist in the continuing search, with authorities racing against the clock to locate the devices. Roughly three weeks from now they will stop transmitting a signal underwater, at which point they will be virtually impossible to locate.
The bodies are being transported, via a nearby archipelago, to the Brazilian coastal city of Recife, where a special morgue is to carry out DNA tests to identify the victims.
The crash on June 1 is the world's worst aviation accident since 2001, and the worst in Air France's 75-year history.
Author: Mark Hallam
Editor: Chuck Penfold