"Dane Spearing" wrote in message
...

So, the initial purpose of this thread was to discuss whether or not one
could use a handheld GPS for IFR navigation. Lots of people have been
tossing around lots of opinions with little or no references to rules or
guidance to back them up (hardly surprising...this is usenet after all...)

Anyway, for my own personal edification and enlightenment, I went and
tracked down the official FAA Advisory Circular that specifies what
the requirements are for the use of GPS under IFR. It's entitled
"Airworthiness Approval of Navigation or Flight Management Systems
Integrating Multiple Navigation Sensors", and is FAA AC 20-130A.
It's about as exciting to read as the dictionary (again, hardly
surprising). However, the Gleim Instrument Pilot Flight Manueuvers and
Practical Test Prep guide (which is where I found the reference in the
first place) does a nice job of summarizing the requirements for use of
GPS under IFR as specified in AC 20-130A. It states:

Authorization to conduct any GPS operation under IFR requires that:
a) GPS navigation equipment used must be FAA-approved and the installation
must be done in accordance with FAA requirements
i) Approval for the use of the GPS for IFR operations, and any
limitations, will be found in the airplane's POH (also called
the FAA-approved Airplane Flight Manual) and the airplane's
logbook
ii) VFR and hand-held GPS systems are not authorized for IFR
navigation, for instrument approaches, or as a principle
instrument flight references. During IFR operations, they
may be considered only an aid to situational awareness.

Aircraft using GPS navigation equipment under IFR must be equipped with an
approved and operational alternate means of navigation appropriate to the
flight.
a) Active monitoring of the alternative navigation equipment is not
required
if the GPS receiver uses RAIM for integrity monitoring.
b) Active monitoring of the alternative navigation equipment is required
when the RAIM capability of the GPS equipment is lost.

This seems fairly clear to me.....


Did you read the first paragraph of AC 20-130A? The third sentence is most
revealing:


1. PURPOSE. This advisory circular (AC) establishes an acceptable means, but
not the only means, of obtaining airworthiness approval of multi-sensor
navigation or flight management systems (hereafter referred to as
multi-sensor equipment) integrating data from multiple navigation sensors
for use as a navigation system for oceanic and remote, domestic en route,
terminal, and non-precision instrument approach [except localizer, localizer
directional aid (LDA) and simplified directional facility (SDF)] operations.
This document does not address systems incorporating differential GPS
capability. Like all advisory material, this AC is not mandatory and does
not constitute a requirement. As such, the terms "shall" and "must" used in
this AC pertain to an applicant who chooses to follow the method presented.
The criteria of AC 90-45A, Approval of Area Navigation Systems for Use in
the U.S. National Airspace System, does not apply to certification of
equipment described in this AC. This AC supersedes previous GPS installation
guidance contained in: FAA Notice 8110.48, Airworthiness Approval of
Navigation or Flight Management Systems Integrating Multiple Navigation
Sensors, and FAA Interim Guidance Memoranda dated February 25, 1991; April
5, 1991; March 20, 1992; July 20, 1992; and September 21, 1993. The
appropriate information contained in those documents is incorporated in this
AC.



Here's another little gem from the Advisory Circular Checklist, AC No.
00-2.15:


3. Explanation of the AC system. The FAA issues advisory circulars to inform
the aviation public in a systematic way of non-regulatory material. Unless
incorporated into a regulation by reference, the contents of an advisory
circular are not binding on the public. Advisory circulars are issued in a
numbered-subject system corresponding to the subject areas of the Federal
Aviation Regulations (FAR) (Title 14, Code of Federal Regulations, Chapter
I, Federal Aviation Administration); and Chapter III, Commercial Space
Transportation, Federal Aviation Administration, Department of
Transportation, Parts 400-450. An AC is issued to provide guidance and
information in a designated subject area or to show a method acceptable to
the Administrator for complying with a related Federal Aviation Regulation.