CONFiture,
The meteorology is dynamic, and I don't believe I've seen a mapping of the atmospheric conditions existing at the time that LH and IB were on the track post ORARO.
Flight LH507 (B747-400) preceded flight AF447 by about twenty minutes at FL350.
The crew reported that it flew at the upper limit of the cloud layer and then in the clouds in the region of ORARO. In this zone they saw green echoes on the radar on their path, which they avoided by changing their route by about ten nautical miles to the west. While flying through this zone, which took about fifteen minutes, they felt moderate turbulence and did not observe any lightning. They lowered their speed to the speed recommended in turbulent
zones. They saw bright St Elmo’s fire on the windshield on the left-hand side. The crew listened into the 121.5 MHz frequency throughout the flight without hearing any message from AF447.
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Flight IB6024 (Airbus A340) passed at the level of the ORARO waypoint at FL370 approximately twelve minutes after AF447.
The crew saw AF447 take off while taxiing at Rio de Janeiro. When passing the INTOL waypoint, they encountered conditions typical of the inter-tropical convergence zone. These conditions were particularly severe 70 NM to 30 NM before the TASIL waypoint. They moved away from the route by about 30 NM to the east to avoid cumulonimbus formations with a significant vertical development, and then returned to the airway in clear skies close to the TASIL waypoint.
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Flight AF459 (Airbus A330-203) passed at the level of the ORARO waypoint approximately 37 minutes after l’AF447.
The sky was clear but the half-moon, visible to the aft left of the aircraft, did not make it possible to see the contour of the cloud mass distinctly. After flying through a turbulent zone in the head of a cumulus congestus formation at the level of NATAL, without having detected this zone on the radar, he selected gain in MAX mode. At about 2 h 00, he observed a first echo that differed significantly depending on whether the radar’s gain was in CAL or MAX
mode. The TILT was set between -1° and 1.5°. He decided to take evasive action to the west, which resulted in a deviation of 20 NM to the left of the route. During this evasive action, a vast squall line with an estimated length of 150 NM appeared on the screen, which was set to a scale of 160 NM. The echoes were yellow and red when the radar was set with gain on the MAX position and green and yellow when the gain was on the CAL position. No
lightning was observed.
ATLANTICO control, informed by the crew of their decision to avoid this squall line by taking evasive action to the east, asked them to return to the airway as soon as they could. This evasive action meant the aircraft flew between 70 and 80 NM to the right of the planned route. In addition, the crew was authorised to climb from FL350 to FL370.
If the crew of AF447 reverted to SELCAL mode (and perhaps even switched to the DAKAR frequency) at 1 h 35 min, they probably missed any communication that may have occurred between ATLANTICO and LH507 on its deviation. Transcripts of communications between ATLANTICO and the LH and IB flights have not been released, nor is there mention in the interim report of whether AF459 was alert to communications between ATLANTICO and IB6024, flying about 25 minutes ahead of them.