View Full Version : Near accident
Since this has not been mentioned yet, here is the CAA FODCOM (http://www.caa.co.uk/docs/33/FOD200316web.pdf)
Makes good bedtime reading!
Frangible
17th May 2003, 00:26
Ouch. I always assumed GPS was a necessary component of EGPWS. Tell me why I shouldn't be worried that it isn't.
a necessary component of EGPWS
No
Tell me why I shouldn't be worried
Looks like you know!
I'm pretty sure there has been a serious suggestion that plates should carry typical radalt readings for a NPA?
400' on a VOR approach WOULD raise a question mark and a few figures on the plate would be VERY useful
...GPS is included for the very purpose of providing useful accurate position data, so the avionics function as intended.
To those that fit equipment that do not include GPS...the question must be asked, why not?
Could it be the old 'distrust' of the USA controlling the GPS signal(s)?
The country in question controls the VOR, do they not?
Captain Stable
19th May 2003, 00:20
It is not permitted to rely on GPS as a primary means of navigation. Nothing, I suspect, to do with suspicion of GPS accuracy in this case - my guess (and it is only a guess) is that this A320 was fitted with INS.
Similarly, INS is not to be used as a primary means of navigation.
The question, however, has to be asked - in this situation, which would have been more accurate - GPS or VOR/DME?
411A - "the question must be asked, why not?" - cost, pure and simple. NOT anti US, however hard you try:O
Capt Stable - "my guess (and it is only a guess) is that this A320 was fitted with INS." - the report says GPS NOT FITTED, so the approach was, I understand, being flown 'raw data', but on a dodgy VOR
Captain Stable
19th May 2003, 02:53
Thanks, yeah - I saw that. My suspicion is that the INS hadn't had a chance to update itself after the long transit, hence the reason for flying it raw data.
Generally it is not permitted to fly approaches using INS (twin IRS, anyway), so it is posssible this would HAVE to be flown in RD regardless of the INS state?
Interesting comments from some, who really should know better.
INS/GPS not approved as a primary means of navigation?
Hmm, have not noticed all that many VOR/DME's at 30West...or 140West for that matter. Last I noticed, pressure pattern navigation was not authorized on the OTS...but hey, maybe I missed an ammendment.
Some EGPWS are equipped with their own dedicated GPS (and terrain data base), thus are able to give warnings as needed.
Best piece of kit to come down the pike in many a moon, IMHO.
Should (IF used correctly) eliminate CFIT, and that is no small achievement, wouldn't you say?:rolleyes:
Several US aircarriers use GPS for approaches (primary means of navigation)...Alaska Airlines the most, so far as I know.
Works good.:E