Europe 1 with AFP 6:18 p.m., November 14, 2022, modified at 6:18 p.m., November 14, 2022

During the trial of the crash of the Rio-Paris flight, the Pitot probes, which measure the speed of planes and which played a major role in the accident, were at the heart of the interrogation of the representative of Airbus.

During this flight, on June 1, 2009, the three probes of the device had frozen.

The plane crashed shortly after, killing 228 people.

A thin metal tube of a few tens of centimeters: the Pitot probes, which measure the speed of planes and played a major role in the crash of Rio-Paris in 2009, occupied the start of the interrogation of the Airbus representative on Monday in the process of disaster.

On June 1, 2009, flight AF447 struck the Atlantic Ocean off Brazil in the middle of the night, claiming the lives of 216 passengers and 12 crew members who had left Rio de Janeiro a few hours earlier to reach Paris.

The A330 was crossing the Intertropical Front (FIT), a difficult weather zone around the equator, when the three Pitot probes iced up, causing the loss of speed indications in the cockpit.

The failure also caused a disconnection of the autopilot, a switch to degraded piloting mode and numerous alarms.

Destabilized, the pilots lost control of the aircraft in less than five minutes.

Judged since October 10 for manslaughter, the manufacturer of the plane must explain itself until Tuesday, by the voice of its representative, Christophe Cail, former test pilot.

Incidents noted

One of the three judges of the court begins by circulating three seals, three Pitot probes, the three models which were at the time installed on this type of aircraft: Thalès AA, Thalès BA and Goodrich.

During the months preceding the disaster, the incidents of probe icing multiplied, almost entirely on the AA model, to a lesser extent on the BA model.

Airbus said it was notified of 13 A330-340 cases in 2008-2009 - out of a total of 20 since 2003.

Why did Airbus not replace the AA probes with other probes?

asks the magistrate.

"At that time, we don't understand what is really going on. We have an upsurge in cases that we don't understand, that we still haven't understood today. And when we want to change, you have to understand what's going on," replies Christophe Cail.

"We contacted Thales to try to understand with them," he adds.

"We have a problem that is not particularly dangerous, we have an increase in cases, and before providing a technical, operational solution, we must come to understand".

The magistrate continues.

The probes of AF447, which had not been changed since the entry into service of the plane in 2005, were they corroded?

They were not found in the debris of the device, fished out from 3,900 meters deep after nearly two years of research.

"It's quite possible", recognizes the representative, while ruling out a link with icing: if corrosion was in question, the "three" probes would not have iced up "at the same time", he argues .

"Precautionary principle"

The magistrate comes to a 2013 study, conducted by Airbus after the accident.

It concludes that, in all cases, the three models of probes would have iced up in the extreme conditions encountered by AF447.

This study played an important role in the dismissal pronounced in 2019 by the investigating judges - a decision then overturned by the Court of Appeal, which led to the trial.

But the study has a "bias", notes the magistrate: it seems to have been carried out with a new AA probe.

"I do not have the answer on the exact age of the probe (...)", declares Christophe Cail.

Airbus had issued a "service bulletin" in 2007, renewed in the fall of 2008, offering companies to change the probes.

But without obligation and at the expense of the company, not Airbus.

Changing a probe cost 1,000 euros, but the financial question, "it's not a subject for us", assures Christophe Cail.

At the time, if they did not impose this change, it was because "we have no assurance that it will improve the problem", he says.

"Why don't you apply a statistical precautionary principle?"

insists the magistrate.

"Before the accident, the elements we have do not show us any particular danger, we are still in the phase where we want to understand", repeats Christophe Cail.

After the Rio-Paris crash, all the probes were replaced and the number of incidents fell to two or three per year.

The interrogation is due to end on Tuesday evening.