XB70
One question I had was on knowing the turn was entered in the FMC.... was this deduced because the next waypoint was seen in ADS data received before shutdown? Has anything specific (lat/long) been divulged?
It would be also interesting to know how ACARS transmitted the information.
If it was VHF, HF or Sat. Maybe the crew forgot at the time to switch off the HF if this was the route out. All 3 can be easily disabled.
If 'they' were going to steal the aircraft then they would most certainly shut it down Before doing anything unusual.
Was it in the secondary in case of emergency and the secondary was activated.
It would seem most odd that highly experienced operators would overlook such obvious detail to put the aircraft into 'stealth' mode.