Report reveals the last minutes of AF 447

[Kip Powick]

Air France Flight 447 took four harrowing minutes to topple from the sky and shatter on the surface of the Atlantic Ocean, according to an expose recently published in Der Spiegel.

More chillingly, the sensor error that likely caused the crash continues to threaten jumbo jets, at least one expert warns.

“An accident like this could happen again at any time,” Gerard Arnoux, head of the French pilots’ union, told the German magazine.

A full account of the investigation into the June 1, 2009 crash is still upcoming. Der Spiegel’s report relies on expert accounting and the currently available sensor data. The flight’s black box has never been recovered.

The Rio-to-Paris flight took off in the evening of May 31 and travelled through a very active storm system that other flights chose to fly around. Turbulence throughout the nearly four hours of flight would have been relatively severe.

Three hours and forty minutes in, ice began to form on the hull of the plane. The exterior temperature gauges malfunctioned, showing a rise in temperature despite a steady altitude of 11,000 metres.

Der Spiegel blames the crash on the failure of so-called pitot tubes – small sensors that sit on the underside of the craft just below the cockpit. The pitot tubes tell pilots how fast their plane is travelling. In this case, they may have iced over or been disabled by ice debris. Whatever the cause, they began begun feeding contradictory data to pilots.

That happened at 2:10 a.m. local time. Four minutes later, AF 447 crashed.

Suddenly unaware of how fast they were travelling, the pilots were forced to manually re-calculate the plane’s correct angle and thrust. Shortly after they began trying to do so, the engines stalled, probably due to the fact that airflow over the wings was no longer providing any lift. AF 447 began to drop.

The plane was falling, but it maintained its attitude. Sensor reports show that the nose was raised upward at a benign 5 degree angle on impact. The plane slammed into the ocean on its belly.

At 2:11, the automatic guidance system could no longer make any sense of the available data. It shut itself off. Once the plane stalled, it was out of the pilots’ control.

At 2:12, the plane was in free fall.

At 2:13, the pilots attempted to restart the plane’s engines. The captain may not have been in the cockpit at the time. His body was later discovered in open water, while his two co-pilots were discovered still buckled into their seats inside the cockpit. The plane was likely piloted by Pierre-Cédric Bonin. His wife also died on the flight.

As it fell, the plane reached downward speeds of more than 150 km/h – the same as a free-falling parachutist. As it dropped below 600 metres altitude, an automated warning voice would have begun bellowing: “Terrain! Terrain! Pull up! Pull up!”

At the point of impact, the plane was under pressure equivalent to 36 times the force of gravity, or 36 Gs. The pilot of a supersonic fighter jet will rarely experience G-forces greater than 12.

In all likelihood, most or all of the passengers on boards were unconscious at the final moment.

At 2:14, AF 447 landed on the surface of the Atlantic fully intact and then shattered. “Exploded” might be a better description – the force was so great that some passengers were sliced in half by their seatbelts. Most pieces of the recovered debris were smaller than one metre square.

Based on the recovered evidence – no oxygen masks deployed, the flight stewards were not buckled into their seats – the sudden drop took everyone on board by surprise. However, it had been a very turbulent flight.

Everyone was likely awake and aware as the power went out and the plane began to plummet. All 228 on board were killed in the crash.

According to Der Spiegel, the icing problem continues to affect pitot tubes on Boeing planes. The company does offer a $420,000 add-on that will allow pilots to calibrate their bearings if the pitot tubes fail. Air France planes do not have that option.

[AME]

Wow I'm guessing there was a lot lost in the translation?

[Kip Powick]

Wow I'm guessing there was a lot lost in the translation?

I would imagine!! Consider the source...bit of a "tabloid" in many senses.

[ChicoChico]

Shortly after they began trying to do so, the engines stalled, probably due to the fact that airflow over the wings was no longer providing any lift.

Fits in with my knowledge of airplanes and aerdynamics

[Moon The Loon]

We'll have to wait until further details are published in North America. Can't wait to get that copy of The National Enquirer

[J.O.]

Pathetic sensationalism, there's just no other way to say it.

[Don Hudson]

Good updates on the BEA site.

The "Alucia" has begun searching in the northern sector of a circular area with the LKP set as the center, using two radii, 10nm & 20nm. A circle of 40nm, with a focus on the inner 20nm was determined from studies of 9 high altitude (going by memory for the moment, FL330 - FL390) LOC events where the outcomes were known, (impact in water, or land, wreckage recovered, data intact). The study indicated that all impacts occurred within about 2.5 minutes of the initial emergency, the distance of flight after the initial event was approximately 14nm.

Admittedly the number of events is small for such determinations but I think it makes sense that the aircraft likely did not deviate widely, turn around for Recife, etc or otherwise fly a long way off course given the reports and the ACARS line stating the Lat/Long at 0210Z.

The search may last for up to four months. By all accounts all parties are determined to locate and recover the recorders.

Don