Originally Posted by
Texandrvr
If there are any companies out there with procedures like this I'd like to know what their procedure is for making sure that you don't turn early on the MAP.
That's a good question. I suspect 99.9% of the times you'll be in radar contact, so you just advise ATC and they'll vector you back around while ensuring your obstacle clearance (if the terrain allows it, they will make you start the Missed approach procedure prior to the MAP).
Now, if you're in a different country, at an airport that has an ILS, but no radar, or if there is a radar outage, then you need to have some alternative means of identifying the MAP. Timing works fine, but what if you forgot to start it?
I think with today's avionics, a crew executing an ILS will have an FMS overlay of the approach anyways, as well as the runway depicted on the nagivation display. So basically you'd fly the LOC until runway threshold (or slightly before it) and start your MAP. In some FMSs, you'll have an FMS waypoint overlayed on the ILS MAP.
Even in a little C172, if you have GPS, you can use it to derive the distance from both the OM/FAF and the LOC antenna. By then looking at the bottom of the approach chart (profile view) you can kinda determine the location of the ILS MAP, at least within a 0.5nm accuracy.
What if you have no GPS/IRS RNAV or don't have any database information for the region AND you don't have radar AND you forgot to start the time? I'm not sure. I would probably climb to the MSA while tracking the localizer and execute the missed as soon as I saw my LOC sensitivity become impossible to track. That should tell me I am either directly over or very close to the LOC antenna (which is 1,000' past the end of my rwy). Although that means I'm probably passed the MAP, if I'm at the MSA I shouldn't hit any obstacles, right?
Any other comments on the above scenario?
What does the AF expect you to do when they fail your GS and you didn't start the time? (BTW, I used to give the exact same scenario to my students
but I always gave them radar services)
PS. I know none of the above procedures are legal (ie. using an FMS/GPS overlay waipoint to identify the ILS MAP) but that's the only thing I can think of in the above scenario. Also, let's be honest, which do you think is more accurate, time or a GPS overlay waypoint ?
