Merged: Erebus site launched

[ampan]

Brian Abraham: The NDB cloud-break procedure was ‘out and back’, starting from a position overhead the NDB at FL200. It wasn’t a straight-line descent.


FGD135: I agree. Something must have been said by the briefing officers about the nav track. If what was said was inconsistent with the charts or the slides, and if any of the pilots had noted the inconsistency during the briefing, then something would have been said. The fact that nothing was said indicates that that no inconsistency was noted - during the briefing.

The material used during the briefing was inconsistent. The audio commentary indicated that the final waypoint was at McMurdo Station, as did the positioning of the simulator overhead the NDB. On the other hand, some of the slides suggested that Erebus would be to the left of track, and a couple of the charts showed the military track, with Erebus to the left of it.

Why didn’t any of the pilots note the inconsistency? My explanation is that there is no inconsistency unless you know that a track to McMurdo Station goes over Erebus. If you don’t know that fact, then you leave the briefing under the assumption that the track goes direct to McMurdo Station and that Erebus will be well to the left of track. It should also be noted that this is not, actually, my own explanation. I only got the idea after reading the evidence of Capt. Ruffell (McFarlane pp 203-206). Of all the pilots who gave evidence about the briefing, his made the most sense and was consistent in all respects (despite McFarlane’s stupid criticisms of it.)

If it is assumed that Capt. Collins left the briefing under the assumption that the track was direct to McMurdo Station and that Erebus would be well to the left of that track, then things fall into place. The night before the flight, he got out his charts and would have noted within a couple of minutes that Erebus was on the track to McMurdo Station. But when he plotted the track using the ‘Dailey Islands’ flightplan he would have noted that this track had Erebus well to the left – which was consistent with some of the material used at the briefing. So he made an understandable error: He assumed that the indications at the briefing of a track to McMurdo Station were wrong, which caused him to not check the McMurdo waypoint before going below MSA.

The other matter to consider is what happened just before the impact, when Capt. Collins decided to turn left. This decision, to me, is not that of a pilot who is certain that he is in the middle of McMurdo Sound. It is much more consistent with that of a pilot who has been given contradictory information.

Although I’m not a member of the Vette fanclub, his work on sector whiteout can’t be argued with. When TE901 levelled out at 2000, then 1500, feet, they must have seen what they expected to see. But that initial impression would have soon given way to a different impression. For example, the false horizon produced by the sector whiteout would not be behaving like a normal horizon. And once the black reference points on either side were out of sight, the false horizon would disappear (which might explain why F/E Brooks was the first to raise the alarm, given his seat position).

Within a few seconds of F/E Brooks expressing concern, Capt. Collins decided to climb out. Some have asked why he decided to turn if he was certain that he was in the middle of McMurdo Sound: Why not just continue straight ahead on the nav track back up to MSA? My answer would be that both Collins and Cassin knew the standard ‘get out’ drill, which is to go back up through the same airspace in which you came down, because you know that the route will be clear of terrain. In other words, a 180 degree turn, once made, gets you back to where you were.


But why did Capt. Collins decide to turn left?

http://www.erebus.co.nz/Background/TheFlightPathControversy.asp