LookingForAJob,
I would argue, also, that the procedures in annex 2 para 3.6.5.2.2 refer to following the flight plan route, rather than all elements of the flight plan.
ICAO Annex 2 para 3.6.5.2.2:
b) in airspace where radar is used in the provision of air
traffic control, maintain the last assigned speed and
level, or minimum flight altitude if higher, for a period
of 7 minutes following:
1) the time the last assigned level or minimum flight
altitude is reached; or
2) the time the transponder is set to Code 7600; or
3) the aircraft’s failure to report its position over a
compulsory reporting point;
whichever is later, and thereafter adjust level and speed
in accordance with the filed flight plan;
oggers states that the aircraft should descend en-route 'as planned'. My view is that this is incorrect because the spirit of the current procedures is to permit ATC to keep other traffic out of the way of the radio-fail aircraft. ATC has no idea where the plog TOD is - something that some might say is evidenced by complaints about late and early descent - and so descending en-route limits the ability of ATC to predict the trajectory of the aircraft after it starts descent.
Nobody said anything about descending at the "plog TOD". When I wrote "as planned" it was in the context of the question "does it mean descent is commenced at the normal point in the
Flight Plan".
Basically, after 7 minutes (or 20mins non-radar) at the assigned level (or minimum IFR altitude if higher) the crew will revert to the filed levels and descend iaw the flight plan. That has been the basic ICAO procedure since at least the early 90s.