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Navigation Aids

capability, the VOR capability must be independent

of the FMS.

[d] To satisfy the requirement for two

independent navigation systems, if the primary

navigation system is GPS−based, the second system

must be independent of GPS (for example, VOR or

DME/DME/IRU). This allows continued navigation

in case of failure of the GPS or WAAS services.

Recognizing that GPS interference and test events

resulting in the loss of GPS services have become

more common, the FAA requires operators conduct-

ing IFR operations under 14 CFR 121.349, 125.203,

129.17 and 135.65 to retain a non-GPS navigation

capability consisting of either DME/DME, IRU, or

VOR for en route and terminal operations, and VOR

and ILS for final approach. Since this system is to be

used as a reversionary capability, single equipage is


3. Oceanic, Domestic, En Route, and

Terminal Area Operations

(a) Conduct GPS IFR operations in oceanic

areas only when approved avionics systems are

installed. TSO−C196() users and TSO−C129() GPS

users authorized for Class A1, A2, B1, B2, C1, or C2

operations may use GPS in place of another approved

means of long−range navigation, such as dual INS.

(See TBL 1−1−5 and TBL 1−1−6.) Aircraft with a

single installation GPS, meeting the above specifica-

tions, are authorized to operate on short oceanic

routes requiring one means of long−range navigation

(reference AC 20-138, Appendix 1).

(b) Conduct GPS domestic, en route, and

terminal IFR operations only when approved

avionics systems are installed. Pilots may use GPS

via TSO−C129() authorized for Class A1, B1, B3,

C1, or C3 operations GPS via TSO-C196(); or

GPS/WAAS with either TSO-C145() or

TSO-C146(). When using TSO-C129() or

TSO-C196() receivers, the avionics necessary to

receive all of the ground−based facilities appropriate

for the route to the destination airport and any

required alternate airport must be installed and

operational. Ground−based facilities necessary for

these routes must be operational.

(1) GPS en route IFR operations may be

conducted in Alaska outside the operational service

volume of ground−based navigation aids when a

TSO−C145() or TSO−C146() GPS/wide area aug-

mentation system (WAAS) system is installed and

operating. WAAS is the U.S. version of a

satellite-based augmentation system (SBAS).

[a] In Alaska, aircraft may operate on

GNSS Q-routes with GPS (TSO-C129 () or

TSO-C196 ()) equipment while the aircraft remains

in Air Traffic Control (ATC) radar surveillance or

with GPS/WAAS (TSO-C145 () or TSO-C146 ())

which does not require ATC radar surveillance.

[b] In Alaska, aircraft may only operate

on GNSS T-routes with GPS/WAAS (TSO-C145 () or

TSO-C146 ()) equipment.

(2) Ground−based navigation equipment

is not required to be installed and operating for en

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


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.


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.


(4) The use of GPS in any other airspace

must be expressly authorized by the FAA Adminis-