background image

6/17/21 

AIM 

route IFR operations when using GPS/WAAS 
navigation systems. All operators should ensure that 
an alternate means of navigation is available in the 
unlikely event the GPS/WAAS navigation system 
becomes inoperative. 

(3) 

Q-routes and T-routes outside Alaska. 

Q-routes require system performance currently met 
by GPS, GPS/WAAS, or DME/DME/IRU RNAV 
systems that satisfy the criteria discussed in AC 
90

100, U.S. Terminal and En Route Area 

Navigation (RNAV) Operations. T-routes require 
GPS or GPS/WAAS equipment. 

REFERENCE

 

AIM, Paragraph 5

3

4 , Airways and Route Systems 

(c) 

GPS IFR approach/departure operations 

can be conducted when approved avionics systems 
are installed and the following requirements are met: 

(1) 

The aircraft is TSO

C145() or TSO

 

C146() or TSO

C196() or TSO

C129() in Class A1, 

B1, B3, C1, or C3; and 

(2) 

The approach/departure must be re-

trievable from the current airborne navigation 
database in the navigation computer. The system 
must be able to retrieve the procedure by name from 
the aircraft navigation database. Manual entry of 
waypoints using latitude/longitude or place/bearing 
is not permitted for approach procedures. 

(3) 

The authorization to fly instrument 

approaches/departures with GPS is limited to U.S. 
airspace. 

(4) 

The use of GPS in any other airspace 

must be expressly authorized by the FAA Adminis-
trator. 

(5) 

GPS instrument approach/departure 

operations outside the U.S. must be authorized  by 
the appropriate sovereign authority. 

4.  Departures and Instrument Departure 

Procedures (DPs) 

The GPS receiver must be set to terminal (

±

1 NM) 

CDI sensitivity and the navigation routes contained in 
the database in order to fly published IFR charted 
departures and DPs. Terminal RAIM should be 
automatically provided by the receiver. (Terminal 
RAIM for departure may not be available unless the 
waypoints are part of the active flight plan rather than 
proceeding direct to the first destination.) Certain 
segments of a DP may require some manual 

intervention by the pilot, especially when radar 
vectored to a course or required to intercept a specific 
course to a waypoint. The database may not contain 
all of the transitions or departures from all runways 
and some GPS receivers do not contain DPs in the 
database.  It is necessary that helicopter procedures be 
flown at 70 knots or less since helicopter departure 
procedures and missed approaches use a 20:1 
obstacle clearance surface (OCS), which is double 
the fixed

wing OCS, and turning areas are based on 

this speed as well. 

5.  GPS Instrument Approach Procedures 

(a) 

GPS overlay approaches are designated 

non

precision instrument approach procedures that 

pilots are authorized to fly using GPS avionics. 
Localizer (LOC), localizer type directional aid 
(LDA), and simplified directional facility (SDF) 
procedures are not authorized. Overlay procedures 
are identified by the “name of the procedure” and “or 
GPS” (e.g., VOR/DME or GPS RWY 15) in the title. 
Authorized procedures must be retrievable from a 
current onboard navigation database. The naviga-
tion database may also enhance position orientation 
by displaying a map containing information on 
conventional NAVAID approaches. This approach 
information should not be confused with a GPS 
overlay approach (see the receiver operating 
manual, AFM, or AFM Supplement for details on 
how to identify these approaches in the navigation 
database). 

NOTE

 

Overlay approaches do not adhere to the design criteria 
described in Paragraph 5

4

5m, Area Navigation (RNAV) 

Instrument Approach Charts, for stand

alone GPS 

approaches. Overlay approach criteria is based on the 
design criteria used for ground

based NAVAID ap-

proaches. 

(b) 

Stand

alone approach procedures spe-

cifically designed for GPS systems have replaced 
many of the original overlay approaches. All 
approaches that contain “GPS” in the title (e.g., 
“VOR or GPS RWY 24,” “ G PS RWY 2 4 ,” or 
“RNAV (GPS) RWY 24”) can be flown using GPS. 
GPS

equipped aircraft do not need underlying 

ground

based NAVAIDs or associated aircraft 

avionics to fly the approach. Monitoring the 
underlying approach with ground

based NAVAIDs is 

suggested when able. Existing overlay approaches 
may be requested using the GPS title; for example, 
the VOR or GPS RWY 24 may be requested as “GPS 

Navigation Aids 

1

1

25