airtren
Perhaps I am posting under a misunderstanding on my part - the PF & PNF had no radio communications at the time when the event started, and they deviated by 12 degrees to the left, without any permission/approval.
They were on UN873, an unidirectional northbound airway, and even though there is comment in the BEA Note that they hadn't managed to logon to DAKAR via ADS-CPDL, they were still (12 mins) inside the ATLANTICO FIR. There are currently no known records of them attempting to call either ATLANTICO (which had their guard) or DAKAR on HF.
There were a number of "off track" deviations made that night by other aircraft passing through the ITCZ, and it is not clear how many requested clearance, or how many just deviated.
Adjacent parallel airways are spaced at 90 NM.