The English language report simply declares, "The position transmitted was the aircraft’s FM position which, in normal conditions, is close to the GPS position."
FM = FMC ?
This implies that ACARS uses the GPS position as a source and not the IRS which may be a few dots off the real position after the loss of nav updates.
SALPU and ORARO position reports
I have found nowhere that these position report were obviously missed. I cannot find that Atlantico said "next report TASIL". SALPU and ORARO arecompulsory reporting points and should have been reported by the crew outside radar coverage. Estimated crossing times from the INTOL report (0133) would have been SALPU at 0148 and ORARO at 0200.
Also Atlantico should have been after these report within a few minutes after they were failed to be reported. It was obviously not.
Though it may be bothering to report every 12 to 15 minutes in a comms hostile environment and with the possible difficulties to get in contact to Atlantico on HF (not seen this in the report, just the inability of other planes to get a response from Dakar which may be due to other reasons as those of us can imagine who fly there) the crew would have normally tried to relay the report though other aircraft on 121.5. Or?
All this sounds theoretical as there seems to be
an accepted lack of discipline about comms and reporting in this part of the Atlantic. I would see this as a contributing factor to the delay of the rescue missions.
A compulsory report is what it says. It is absolutely necessary that ground stations can expect that reporting duties are taken serious and a missing report signals something critical. It is then necessary that ground stations become alert immediately if a report is missing and an alert distress phase is initiated.
Even if the relict of propeller flying, which HF is, is not working there are other means to get a report passed on to the controlling center as Iridium phones or SATCOM ACARS to homebase operator and then by phone or SITA through landlines.
The reliance on "modern"technologies as ADS-C and then give up to report as they may not work is not adequate. However ADS-C in this case was present for the Dakar FIR only, not the Atlantico FIR.
I could not imagine that neither airside nor landside behaviour would have happened inside Gander or Shanwick airspace.