There is one strange but not necessarily consequential omission in the official interim report into the AF447 disaster.

Nowhere does it confirm that the weather radar was switched on.

It says the ‘correct functioning of the radar’ would have been checked during taxiing to take off. And it summarises the Air France radar operating procedures, which are that its use in monitoring clouds is obligatory at all times except when there are none and it is broad daylight.

This has been a week in which to re-read the interim report following the release of the alternative report by the Air France pilot union. (In French, and in parts, difficult, technical French.)

The official report, as per all interim crash reports, came to no firm conclusion as to cause, but did provide evidence that the jet experienced unreliable air speed indications from Thales designed external pitots since ordered removed from all but a minority number of stations on Airbus A330 and A340 jets. It concludes that the jet was substantially intact until it struck the ocean at a high speed while pointed forward in the direction of flight.

The pilot union report acknowledges the complexity of the still unresolved chain of events that is emerging in the inquiry, but states categorically that if the pitots had not been blocked with ice the crash would not have occurred.

The difficulties that Airbus A330 and A340 pilots face with that particular brand of pitot (not used by Qantas on its A330s) and with claimed flaws and risks in the recommended Airbus procedures for dealing with this problem have been widely reported, by Plane Talking here and in technical journals.

But the nagging question remains, how much more difficult would that task have been if the pilots did not have a fully functioning weather radar on the flight between Rio de Janeiro and Paris on June 1?

If in the darkness of the middle of the night, faced with airspeed issues, they could not use radar to assess the strength and proximity of violent and potentially very dangerous storm cells?

This is a hypothetical, but also legitimate question, in that it has not been established if the radar was in full use, and it can be useful sometimes to ask what areas or issues have not been ruled in, or out, or off.

Air France has not responded to queries in regards to this.

On June 1 every major media source in France quoted Air France as saying that automated messages from the flight indicated electrical failures and could have meant that the jet, carrying 228 people, had been struck by lightning.

Reports also said Air France claimed the pilots had reported severe turbulence in their last voice contact.

In fact the official interim report says that no satellite voice communications took place between the flight and Air France.

The only voice communications documented in that report are routine positioning reports to air traffic control. Those communications ended well before the accident happened, when the flight failed to respond to three requests to confirm the estimated flight time to the next waypoint on its course, TASIL, which was only minutes, at cruising speed, beyond the estimated point of impact on the sea.

This is the start of a period in which the automated ACARS maintenance and status monitoring messages indicate the onset of significant faults in the systems on the jet, including the usual prelude to trouble in the office, the involuntary disconnection of the autopilot and reversion to what Airbus calls ‘alternate law’ in the manual use of flight controls.

A third search of the complex and deep seabed in the crash zone for the missing ‘black box’ flight recorders is expected to begin soon.

Air France has also announced an independent audit of its safety procedures and training.