The main Brazilian Naval search and recovery flotilla of four ships is now deep into the debris field as night falls on the third period of daylight in the crash zone.
The location of AF447 on transmission of final automatic message alerting vertical cabin speed and preceding flight path overlaid on satellite data on cloud cover and height as near to that moment as the information provides as broadcast by BBC 1 overnight.
There was a bomb threat made against an Air France flight prior to departure for Paris from Buenos Aires last Wednesday. No bomb was found.
Reports in Paris and technical commentaries in Europe and elsewhere are unanimous that there was a violent or explosive decompression of the jet at a significant altitude.
Meteorological evidence, much of it from weather satellites, shows that the cloud tops in the storm zone through which the Airbus A330-200 was flying had exceeded 50,000 feet in many places with at least a few readings of 60,000 feet or more. These figures are less than commonplace in that area, but neither are they rare or unknown and have been widely reported since accurate records began with jet services in the 60s. Normal storm top heights in the region seem to be below 40,000 feet, lower than usually reported in other tropical convergence zones, but by reputation, more violent despite the lower heights.
The French weekly Le Point is reporting that white frost had appeared around pitot points which are used to generate some of the air speed vectors fed into the ADIRU units.
It is not clear how this could have been known at the time, as ice accumulation would have been detected by the systems rather than observed. It is important to note that the design of ADIRUs takes into account the higher than ground speed readings of air flow that are generated close to parts of the surface of a jet by aerodynamic effects.
This entire line of speculation like any other needs to be treated with great caution. It may not be relevant. Nobody really knows.
The most recent airworthiness directive on the model of A330-200 involved in this crash does not include the ADIRU units, in so far as the data base reveals. It is a broad directive issued in March concerning mandatory changes to an electrical system harness behind the toilet area at rear of the aft cabin to prevent malfunctions which could cause cabin pressurisation failures and could cause up to 32% of the passenger oxygen masks to malfunction.
While this sounds dramatic it is, in airline terms, just a typical or routine airworthiness directive similar to the many that are issued or amended in relation to all types of aircraft to remove any potential issues that are picked up in the course of their operations. The more a jet type is used the more ADs it generates. For the most part, they are precautionary.
Air France and other A330 and A340 operators have more than a year left in which to comply with this directive in those aircraft where the modifications have not already been made during the production of very recent deliveries.
