That means GPS is required for the Approach. So why the DME or RADAR required for LOC only. GPS can be used to identify FOVES.
For the LOC only approach, you have to radar service, DME, or RNAV for FOVES. You also need RNAV for the published miss to YUNUD. ATC can also assign an alternate miss.
Send an inquiry to the design folks. They are pretty quick to respond. I found a similar one at Plattsburgh, NY. I asked and they agreed it's unnecessary to have the DME requirement. Probably will be fixed the next time they get around to amending the procedure. BTW, I think we are going to see a lot of these DME leftovers as RNAV TAAs and waypoints continue to replace ground based fixes.
I don’t believe it’s a TSO requirement to be able to display GPS distance when using ground-based navigation, so identifying FOVES via GPS may not be possible on some systems. Obviously GPS can be used in lieu of DME for this application, so if your system can display both, GPS is fine.
Are you thinking of any particular GPS system that has RNP APCH capability without a database that includes the ability to load the waypoint (if not the entire approach)?
No, but I’m thinking of one that can’t display GPS distance on the PFD when a localizer is displayed as the nav source.
Sure. Display of information can be an issue. But why do you need to if you can load the waypoint or the procedure?
When using steam gauges instead of a PFD or eHSI, in the units I'm familiar with, on multiple pages, it appears on the default NAV or FMS screen and the flight plan, at a minimum. Here's it is on an "ancient" 430. What's the system you have in mind?
Yeah. The point I'm getting at is you have to have GPS to do the Approach in the first place. GPS is an authorized substitute for DME. There is no Alternate Missed Approach Procedure for this Approach according to the Terps documents.
I suppose so. Another interesting thing on this one is the 4 mile holding leg or 1 minute. I think that will become more common. Not a bad idea.
It's a named fix, in the data base. That suffices to substitute GPS. But maybe some combinations of Navigators and Data Bases may not have it. I dunno. I doubt it.
I guess if you didn’t see the gymnastics we had to go through on the earlier systems to be able to use them IFR, you don’t question that it’s always been the way it is now. maybe intersection holds with only one VOR receiver we’re more useful than we thought.
I know it hasn't always been the way it is now. I learned instruments with dual nav/com and an ADF. I considered myself lucky to have the dual nav/coms. I got super excited when I first saw DME, not to mention a KNS80 RNAV box! Ooooooh! And I remember the gymnastics of continuously having to spin the OBS on NAV 2 when a localizer approach had multiple stepdowns (one of my instructors insisted I do that for situational awareness even on an ILS). Sadly, AFAIK, the amount of gymnastics needed to perform a task the system is capable of has never been part of the FAA's equipment requirements for an approach.
Have you ever identified the regulatory requirement for a waypoint annunciator above the attitude indicator?
No. I never even looked for one. I wasn't aware there was one. I'm pretty sure I've seen systems with none.
I’m pretty sure I’ve seen systems with none as well. I’m just as sure I’ve seen systems that required them. And that requirement is the basis for my position, so feel free to look it up if you want to continue this discussion.
Is that why controllers give you the distance to the fix when clearing you even on a RNAV approach "Piper 1234 you're five miles from GRAPE, turn left 030, maintain 2,100 until established, cleared for the RVAV 10".
I don't think so. IIRC the PTAC call, Position, turn, altitude and clearance is required phraseology that Controllers have to use for all approaches.
That sequence of information was a direct result of the TWA514 crash west of Dulles in 1974. If you're not familiar, it's a pretty interesting report from the standpoint of ATC - pilot expectations and interaction on an instrument approach.
I read the the Wikipedia article on TWA 514 but am having a hard time picturing in my head what happened. Maybe it's because that type of flying environment is way before my time. Or perhaps it's because the article was written for a layman rather than a pilot. What's your take on the accident?
They descended to a published altitude before they were on the approach that protected that altitude.
I haven't read through it, but this article appears to have a little more of a pilot-focused discussion: https://admiralcloudberg.medium.com/a-different-approach-the-crash-of-twa-flight-514-4047166234ee
