You can monitor the GPS for distance. Distance to BUYAB and then distance to the MAP. When you cross MCN the GPS sequences to the next waypoint which is BUYAB and you will be 6 miles from it. When you cross BUYAB the GPS will sequence to the next waypoint which is the MAP, you will be 2.8 miles from it. Halfway there it wil say 1.4 to go. This would coincide 7.4 from MCN but you don't have to do the math. Just before you get to the MAP it will say .1 to go, now 8.7 from MCN. This is of course if your GPS unit loads the fixes inside the FAF. In other words you don't have to monitor your distance from the DME source if the GPS loads the fixes and tells you when you are over them.
Yeah. You can even do that with Localizer/DME's. Load up Direct to "I" whatever the identifier is and you will get distance from the Localizer/DME antennae. Can't really think of why you would except when the "unit" won't load the approach and you want to use it instead of a DME reciever.
There are other places where a localizer’s DME signal is used. For example, the MSP Class B airspace rings are measured from the I-MSP DME. I just wish the localizers would be listed in the nearest VOR page on my 430W. I use that page as a DME substitute rather than direct-to the VOR. That way I don’t have to interfere with my flight plan or loaded approach (and associated missed approach) to get DME information. But I can’t figure out any way to measure DME from a localizer other than direct-to.
Hmm. I wouldn't think that using the distance to a VOR on the 'Nearest Page' would qualify as an authorized substitute for DME but who knows. If the Nearest Page updates frequently enough, why not?
It's updated continuously. I don't know of any regulation or interpretation relating to using GPS to substitute for DME that requires you to set your equipment to navigate to the navaid. On the 430, you would have to have it as your next flight plan waypoint (using direct-to or otherwise) in order to get a distance read-out. Using the NRST chapter, VOR page in the 430 gives you the quickest access to the substitute DME information with no interference with your flight plan.
In any of the Garmin units that have an EHSI, you make IMSP the active waypoint an the RMI will handle it like a VOR/DME.
That's what I meant, sorry if I bungled on communicating it. Actual VORs conveniently show up in the NRST VOR page, but localizers don't, so you have to make the localizer your active waypoint to get substitute DME information. Like I said in a follow-up post, in the GPS era it has become a corner case to ever need a DME measurement except on an approach and then you will have the approach loaded into your navigator anyhow. But if you want DME to a localizer facility that you aren't flying toward, you have to sacrifice the flight plan in your navigator to get that information.
EHSI ????
G-1000 example:
Well, if he covers the GPS, you just lost your DME unless you have another separate DME receiver. It's a VOR -A DME, no DME/GPS, no approach.
It's just a VOR-A approach. KMAC. DME will let you identify BUYAB to get lower minimums. You're also welcome to use it for the Missed Approach Point. The Missed Approach Fix is both an intersection and a DME Fix so you're also welcome to use DME there.
Jeppesen codes the MAP as MA028, FWIW.
Yeah. Thats got me wondering. On the Approaches that Jeppesen has chosen not to include stepdown fixes inside of the FAF to save storage space, is 'MAxxx' still there? I'd think so, but..
Yes it is.
Now that is interesting!
They plan to have the LOC procedures separated in the Jeppesen in the future, for avionics that are not memory limited. Garmin presently does it for its Americas subscription, because that doesn't overload database memory, even on older units that are limited to 20 megs.
