Ok, framer, just how do you go about making an instrument approach? You do it by placing trust in people that have designed and drawn up the procedure.
Yes you do FGD. Good point.There is a certain amount of trust required to operate. You also do it with a lot of checking and cross checking and a healthy amount of distrust. eg do you just assume that the glidepath is accurate or do you use your altimeter to cross check and confirm it is by referenceing to a DME when you commence the approach? That cross check isn't part of the proceedure, it is an SOP or a personal habit designed to identify any holes in the cheese or loss of S.A.
Although I was talking about confirming position prior to descending through MSA the concept is similar. Do you assume that the RNAV system is faultless and that flight planing and your crew and you yourself have made no errors? Or do you relentlessly cross check, confirm and verify things? It is a constant part of the job, we are always doing this.
Framer, the only checks they had at the time were visual
I don't think that is true.
Prior to leaving 16,000ft they needed to verify their position.
If they had plotted the lat/longs onto a map it would have highlighted the anomaly.
If they had remained at MSA until a radial DME check confirmed their position it would have highlighted the anomaly.
If they had remained at MSA until visually past Erebus it would have highlighted the anomaly.
If they had remained at MSA until overhead the station their position would have been verified.
I imagine you'l respond to this by saying that they couldn't get the DME or a radial, my response to that is that is even more reson to remain at MSA, it casts doubt as to why things aren't as expected.
When I argue this point it always sounds as though I'm saying I would have done better. I'm not. I don't know how I would have gone in the same situation. I'm using the luxury of hindsite and reports and also have the decades of learning the industry has gone through to help me. I'm lucky enough to be able to learn from the mistakes this crew made.
By saying they never made a mistake we are running the risk of missing out on some very important lessons.