altered waypoint ... was thereafter maintained ... as an approved
position", it is necessary to understand the reasons given by the
Commissioner for the change back to Williams Field. If the altered
waypoint had been adopted as a better position why was it then thought
that it had to be discarded?


Correction of co-ordinates

It was not until 14th November 1979 that any question arose about the
McMurdo waypoint. On that day Captain Simpson had taken the second
November 1979 sightseeing flight to the Antarctic and something
persuaded him to raise the matter of the southern waypoint with Captain
Johnson, the Flight Manager Line Operations. There is a difference of
opinion as to precisely what was said by Captain Simpson to Captain
Johnson but according to the evidence of those in the navigation section
they thought that when they checked up-to-date records of the
co-ordinates at McMurdo Station against the original NV90 flight plan
what had been brought forward for notice was the small difference of 10
minutes of longitude to which reference has been made. They said this
represented the recent relocation of the tactical air navigation system
(the TACAN) at Williams Field. Accordingly Mr Brown of the navigation
section wrote into his worksheet a corrected position of 77° 52.7' S and
166° 58' E and entered those figures into the system on 16th November.
But the amendment was not made in the live flight planning system until
the early hours of 28th November. According to the members of the
navigation section all this was done without knowledge that the effect
of introducing the amended figures would be to override "164° 48'" and
so alter the co-ordinate by 2° 10' rather than 10'.