Is your IFR GPS still legal for use?

"Neil Gould" wrote in message
t...
Recently, Steven P. McNicoll posted:

"Roy Smith" wrote in message
...

But it's legal to fly those very same approaches with a 30 year old
ADF which points vaguely in the direction of either 1) the radio
beacon, 2) the
nearest T-storm, or 3) some other random propagation anomaly, and an
equally ancient DME which is doing good if it's correct to within 1/4
mile.
Gotta love the FAA. A fine example of why getting all the government
you've paid for is a bad thing.


You can't substitute GPS for ADF on an NDB approach.

Of course not. If one did that kind of thing, they might actually arrive
at their intended destination.

Neil


The reason the FAA have done this is set out in the AC it is to harmonise
with ICAO.

"This criterion is consistent with the ICAO guidance material for the
implementation of area navigation (RNAV 1 and RNAV 2) operations. AC 90-100
became effective 7 January 2005. Since then, ICAO has continued to harmonize
area navigation (RNAV) performance criteria. AC 90-100A reflects these
harmonized ICAO performance-based navigation criteria as well as lessons
learned from the initial US RNAV implementation. "



US aircraft had real difficulty operating under IFR in Europe as AC90-96A
and JAA TGL -10 shows.

One of the reasons why Cirrus and the like have been having to fit ADF and
DME into their Europe bound aircraft.