GNSS / GPS use & safety tips

GNSS / GPS:

• Satellite position and time (CAR 101.01(1), TC AIM COM 5.1).
• Direct track to any point, not a radial; gives groundspeed, track, time to destination (TP 1102, Navigation Instruments).
• Signal can be lost or degraded (COM 5.3.1).

GNSS safety tips (TC AIM COM 5.11):

• Never fly below a published minimum altitude in instrument conditions on GNSS confidence.
• VFR GNSS receiver only supplements chart reading in visual conditions, never replaces charts.
• Position handhelds and cables clear of aircraft controls (a handheld with a valid database can back up a failed panel unit).
• Do not push into marginal VFR weather on GNSS confidence: current VFR charts updated by NOTAM remain primary.

GPS use limits (PHAK ch.16):

• GPS altitude unreliable: large vertical error possible, no integrity check. Never replace altimeter.
• Never fly on GPS alone: integrate with other electronic nav, pilotage, dead reckoning.

Suspected interference in flight (jamming device, bad fix, unexplained RAIM flag) (TC AIM COM 5.10):

1. Advise ATS (air traffic service) in flight, not only after landing.
2. Revert to other nav aids if needed.
3. Complete a GNSS Anomaly Report Form (NAV CANADA). It follows the ATS call; it does not replace it.

Trap: pushing into marginal VFR weather because the GNSS track looks clear.

Practice