Required equipment to fly RNAV (GPS) approach
Asked by: Anderson 6890 views Instrument Rating
Refer to the Phoenix Deer Valley (DVT) RNAV (GPS) RWY 25L approach plate.
In the top margin, adjacent to the textual missed approach instructions is the notation: "DME/DME RNP-0.3 NA."
I fully understand what this restriction means (e.g., unsuitable/unavailable DME facilities).
However, since properly certified GPS equipment capable of delivering RNP 0.3 accuracy is a requirement to fly this approach, under what circumstances would DME/DME derived RNP 0.3 ever be an issue?
In other words, the fact that this annotation (DME/DME RNP 0.3 NA) is shown on the approach plate at all suggests that if it were not for this restriction an aircraft that is not GPS equipped, but could nevertheless deliver RNP 0.3 accuracy, would be legally allowed to fly this approach. For example, an aircraft that had a FMC (Flight Management Computer) system deriving position information from DME/DME/IRU could use the LNAV minimums (assuming the DME/DME RNP 0.3 NA annotation was not on the approach plate).
I guess I'm puzzled as to why this DME/DME RNP .03 NA restriction is even on the approach plate since GPS equipment capable of delivering RNP 0.3 accuracy is mandatory based on the approach plate title ( RNAV (GPS) RWY 25.
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