Most of the newer GPS units do not allow an offset to be selected.
In this instance ASTB has stated that the aircraft was 3.83 degrees offtrack all the way from Jervis Bay.
Offset tracking on older GPS units only allows parallel tracking ie selecting a distance of track eg 2nm and this is held constant until the offset is cancelled.
If the waypoint BLAEG was inadvertantly selected rather than BLAED this would put the aircraft about 2 degrees left off track, but not 3.83.
Tracks/ Distances:
YJBY- YBLA 235M 244nm
YJBY- BLAED 235M 230nm
YJBY- BLAEE 234M 229nm
YJBY- BLAEG 233M 234nm
3.83 degrees off track over 230nm by 1:60 would be 14.69nm south of track. Would be interested to know exactly where it crashed. I believe it was last seen on radar 10nm east of BLAEE at 5000'.
This would put it right on the edge of the 25MSA limit which is 5000'.
Whilst safe it would be unusual for an experienced pilot to be at this level so early as the approach starts at 5000'.
Appreciate any comments
BH