Originally Posted by Silvertate
>>TCAS assisted incidents.
The Swiss collision would not have happened without TCAS. It was a total system usage error that had not been fully thought through and promulgated to all airlines and crews before the incident.
Rubbish; the TCAS was going to save them; the Russians didn't follow the TCAS instructions like they were supposed to. Don't blame the (pretty simple) technology for human incapacity.
Originally Posted by Silvertate
And the multiplicity of notation does not help. The USA might have RNP-AR, but in Europe we generally have RNAV GNSS. EPKT Katowice in Poland or EGBB Brum in the UK are GNSS approaches. There are a few around. LTBS Dalaman GNSS in Turkey is more pertinent to this thread, as it goes through the hills and is offset.
Come on. Working out the difference between RNAV GNSS and RNP-AR is pretty basic stuff. Surely you don't just call up an approach in the database and say "gee this looks good, let's give it a go!"?. That
Turkey approach is a bog-standard RNAV (GNSS) that the world has been doing for years and is "tiger moth" stuff compared to an RNP-AR. It has got a minor kink early on but is dead straight from 3000ft down. Offset? Yes, and that is much less desirable than that RNP-AR at Kathmandu. As pointed out earlier, RNP-AR has an aligned final. You seriously need to get into Google and understand what you're talking about before carrying on here.
Originally Posted by Silvertate
The satellite constellation is fixed, while the Earth rotates inside it. Thus the number of satellites you can see, and the declination and azimuth of those satellites, will change during the day (and with your location). Some locations and times are better than others - especially if there is a satellite outage in your area.
You can't be serious...
Originally Posted by Silvertate
>>IRS backup.
Worse than useless. As I said before, our IRS fix can easily be a couple of miles away from the GPS fix, and the VOR/DME is not much better in mountainous terrain. So if you lose the GPS on the approach, and the FMC position reverts to IRS fix position, you get a rapid 2nm map-shift. Ok, so the nearest mountain peak is only a couple of nm away, and the autopilot is trying to recapture the new IRS trackline which is 2nm away - your move, as they say...
I now see why you're so worried about the "mystical" GPS. If you "lose the GPS" and have a sudden 2nm map-shift your outfit shouldn't be doing GPS approaches, period. Sounds like a bunch of cowboys trying to do the good stuff with totally unsatisfactory gear.