Definition
A Global Navigation Satellite System receiver that meets the FAA's technical and operational standards (TSO-C129, TSO-C145, or TSO-C146) for use as a primary navigation source under Instrument Flight Rules. To be IFR approved, the installation must be certified for the specific phase of flight (en route, terminal, or approach), be properly installed per an approved data package, and be listed in the aircraft's Aircraft Flight Manual or Supplement as authorized for IFR use.
Plain English
A satellite-based navigation unit that the FAA has cleared for use when flying on instruments. Not every GPS in an aircraft qualifies — it must meet specific standards and be officially installed and documented for IFR flight.
Context Anchor
Seen on IFR en route low altitude chart information and in instrument procedure discussions when a route, fix, or procedure depends on approved satellite navigation equipment.
Derivation
GNSS stands for Global Navigation Satellite System — the broader family of satellite navigation systems that includes GPS. The FAA uses GNSS as the umbrella term because approved equipment may use GPS alone or GPS combined with augmentation systems like WAAS.
Why Pilots Care
Allows use of satellite navigation for en route and approach operations without relying solely on ground-based aids, provided the equipment meets regulatory standards.
Intuition Check
Do not assume “approved” means the unit simply works or shows an accurate position. Here, “approved” means the equipment and installation meet the rules for IFR use in that aircraft and for that operation.
Example Sentence 1
The route segment was marked for use only by aircraft with an IFR approved GNSS, so the pilot verified the AFM Supplement before filing.
Example Sentence 2
On the low altitude chart, the note indicated that IFR approved GNSS was required for the RNAV airway.