Yes, you can fly approaches with the GPS but you have to have the required equipment on board, serviceable, tuned and displayed. Same for the airlines. E.g. Southend EGMC NDB ILS DME 24 you need all three.
The GPS is not “replacing” the ADF, VOR or DME, as it can in the States.
Flyer59 wrote:
Fior sure they allow the substitution of DME by GPS …
This is a bit surprising. I’d say that the navaid where substitution is least likely to work is the DME.
I don’t think any EASA country allow substitution (i.e. not carry the underlying receiver).
DME is certainly not allowed to be substituted by GPS. In no EASA country you are allowed to fly any procedures requiring DME without having an operational DME receivers and some countries even ban all aircraft without DME from their airspace (Germany is the most famous example).
My hope is that EASA will bring an equipment substitution concession just like in the US — a job for @bookworm!
( I was talking about the US where it’s legal to substitute a DME with GPS)
In the US, the GPS can be used to substitute for a DME, NDB, or VOR or any ATD determined from a waypoint. On an approach, the GPS may be used except for the final approach course, which must be flown with the designated VOR or NDB unless the approach is an overlay procedure that has “or GPS” in the title. Flying a localizer, even outside of the FAF requires that the raw data be displayed
Why is it that above FL240 in the U.S., DME can NOT be replaced by GPS if navigating on an airway requiring VORs?
Rwy20 wrote:
Why is it that above FL240 in the U.S., DME can NOT be replaced by GPS if navigating on an airway requiring VORs?
This was changed in 2007.
91.205 (e) now reads:
(e) Flight at and above 24,000 feet MSL (FL 240). If VOR navigation equipment is required under paragraph (d)(2) of this section, no person may operate a U.S.-registered civil aircraft within the 50 states and the District of Columbia at or above FL 240 unless that aircraft is equipped with approved DME or a suitable RNAV system. When the DME or RNAV system required by this paragraph fails at and above FL 240, the pilot in command of the aircraft must notify ATC immediately, and then may continue operations at and above FL 240 to the next airport of intended landing where repairs or replacement of the equipment can be made.
Being a cheapskate always comes at a price and that price in this case is likely to be your last mistake if you are not exceptionally vigilant.
Using GPS distance to replace DME for approaches is a problem as the precise position of the DME station is not necessarily the zero position of the DME station and so your checks of altitude vs glide slope may well be in error.
This is most likely to be a problem with airfields that have multiple radio aids with the same ident, I know of one such airfield that is so configured and a data base error had the VOR/DME position accidentally transferred to the NDB position about three miles away, the results of flying an NDB or VOR approaches based on this database mistake could end very badly. At least if you have the VOR/ DME & ADF fitted and monitor them the discrepancy between the GPS and other radio positions will become apparent.
Aviation is becoming far too reliant on GPS, but it is not the reliability of the GPS equipment or the GPS signal that is likely to kill you, it is errors in the database or mis-selection of an incorrect waypoint ( with the same or similar ident ) that is likely to be the thing that kills you.
A_and_C wrote:
the precise position of the DME station is not necessarily the zero position of the DME station
That’s possible. However, DME stations with nonzero displacement aren’t exactly numerous, the EAD database lists 5 in europe:
NL PONTA DELGADA 0.897nmi
PR PORTO 0.177nmi
ILB LISBOA 0.189nmi
ILI LISBOA 0.176nmi
SPA LULEA 270m
A_and_C wrote:
your checks of altitude vs glide slope may well be in error
For Ponta Delgada, the error would be in the order of 300ft, thus significant. For the others, the error would be in the order of 50ft, so about the same order of magnitude as the altimeter error.
A_and_C wrote:
it is errors in the database
This is one of my pet peeves, aviation database quality just sucks, despite (or because of?) LoAs.
tomjnx wrote:
That’s possible. However, DME stations with nonzero displacement aren’t exactly numerous, the EAD database lists 5 in europe
That list is not exhaustive. I just learned that the Lydd ILS-paired DME is displaced some 300 m.
