malibugrif
Filing Flight Plan
- Joined
- Oct 7, 2009
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malibu
This is an answer that I want to be on the wrong side of. A pilot at KMYF asked if the KMYF ILS LOC 28R approach which is noted as “DME Required” applied to his G1000 equipped airplane. My first thought was although the plane has no DME, it does have a panel mounted, database current, certified GPS that’s at least as accurate and reliable as DME. However, as I research the issue, I’ve come to the conclusion that no, the plane must be equipped with DME. Please tell me where my logic goes astray.
1) The approach is not marked GPS. As we know from the Sept 22 discussion on this board, AIM 1-1-19(g), tells us , “all the approaches that can be used by GPS now contain “GPS” in the title”. So that would seem to prohibit the use of the GPS in lieu of DME.
2) What about AIM 1-2-3(c), which allows the GPS to identify a DME fix where the airplane is not equipped with DME. However, note 3 specifically indicates that “Pilots may not substitute [GPS] for the navigation aid providing lateral guidance for the final approach segment.” In the case of KMYF, one of the DME waypoints is the FAF, part of the final approach segment.
3) Finally, turning to the Garmin’s AFMS, a limitation on the GPS states, "Accomplishment of ILS, LOC ... or any other type of approach not approved for GPS overlay with the G1000 GPS receiver is not authorized.” That seems definitive to me, that if he needs DME to accomplish the approach, he can’t do so with the G1000.
Again, logic tells me that if the approach is in the database, which it is, the pilot should be able to fly the approach using the GPS database for the purpose of identifying the DME waypoints. Yet, I'm coming to an opposite conclusion. (In your answer, please ignore there exists a perfectly good RNAV approach into this same runway. The question is really about the DME “requirement”.)
1) The approach is not marked GPS. As we know from the Sept 22 discussion on this board, AIM 1-1-19(g), tells us , “all the approaches that can be used by GPS now contain “GPS” in the title”. So that would seem to prohibit the use of the GPS in lieu of DME.
2) What about AIM 1-2-3(c), which allows the GPS to identify a DME fix where the airplane is not equipped with DME. However, note 3 specifically indicates that “Pilots may not substitute [GPS] for the navigation aid providing lateral guidance for the final approach segment.” In the case of KMYF, one of the DME waypoints is the FAF, part of the final approach segment.
3) Finally, turning to the Garmin’s AFMS, a limitation on the GPS states, "Accomplishment of ILS, LOC ... or any other type of approach not approved for GPS overlay with the G1000 GPS receiver is not authorized.” That seems definitive to me, that if he needs DME to accomplish the approach, he can’t do so with the G1000.
Again, logic tells me that if the approach is in the database, which it is, the pilot should be able to fly the approach using the GPS database for the purpose of identifying the DME waypoints. Yet, I'm coming to an opposite conclusion. (In your answer, please ignore there exists a perfectly good RNAV approach into this same runway. The question is really about the DME “requirement”.)