I find it very difficult to write about this story, let alone read about it. A plane crash of this kind is perhaps my greatest terror, and for it to happen in this day and age with a modern plane from a long-established airline is unthinkable. There are however some unconfirmed rumours coming from the investigation (which it turns out received significant amounts of data transmitted by the plane before it broke apart):
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.
Jean Serrat, a retired airline pilot, told Agence-France Presse: “If the BEA [accident investigation bureau] is making a recommendation so early, it is because they know very well what happened. If they know what happened, they have a duty to make a recommendation, for safety reasons … The first thing you do when you fly into turbulence is to reduce speed to counter its effects. If you reduce speed too much you stall.”
Why would they reduce speed too much?A theory has appeared in the New York Times:
Airbus, the manufacturer of the missing jet, issued a warning on Thursday to all its customers to follow established procedures when pilots suspect airspeed indicators are not functioning properly. The bulletin appeared to be the first hint that malfunctioning instruments indicators might have played an important role in the crash.
The message, approved by French investigators, said that the message had been sent “without prejudging the final outcome of the investigation,” but clearly it pointed to the possibility that mismanaging the plane’s speed could have been one step in a cascade of on-board failures, leading to the crash northeast of Brazil on Monday and the death of all 228 people on board.
The message noted that “there was inconsistency between the different measured airspeeds” in the Airbus 330 that crashed, one of several error messages that were sent by the plane’s automatic systems to an Air France maintenance base.
Airspeed on jets is measured by the combination of a tube that faces forward, called a Pitot tube, and an opening on the side of the plane known as a static port. The plane’s speed is determined by comparing the pressure in the Pitot tube that is created by the oncoming wind with the pressure from the static port.
The model that crashed, an A330, has three pairs of tubes and static ports. But other instruments can also be involved in calculating air speed, and the notice to airlines, called an Accident Information Telex, did not specify the nature of the inconsistency.
The Wall Street Journal goes further:
But tropical thunderstorms that develop in the area where the plane was flying often form tiny particles of ice at high altitudes, and air temperature at the plane’s altitude is below zero.
A theory is that ice from the storm built up unusually quickly on the tubes and could have led to the malfunction whether or not the heat was working properly. If the tubes iced up, the pilots could have quickly seen sharp and rapid drops in their airspeed indicators, according to industry officials.
According to people familiar with the details, an international team of crash investigators as well as safety experts at Airbus are focused on a theory that malfunctioning airspeed indicators touched off a series of events that apparently made some flight controls, onboard computers and electrical systems go haywire.
The potentially faulty readings could have prompted the crew of the Air France flight to mistakenly boost thrust from the plane’s engines and increase speed as they went through possibly extreme turbulence, according to people familiar with investigators’ thinking. As a result, the pilots may inadvertently have subjected the plane to increased structural stress.
Very very sad. And very very scary. I’ve been panicky about pilots flying through severe weather for a few years now. Apparently with cause. I hope lessons are learned should this be determined as the likely cause, given that the black box flight recorders are unlikely to be retrieved from the Atlantic Ocean floor.