Definition
A grouped reference to the three primary precision or near-precision approach types used to align an aircraft with the runway during the final approach segment: ILS (Instrument Landing System), which uses ground-based localizer and glideslope transmitters; RNAV (Area Navigation), which uses GPS and onboard navigation databases to fly published lateral and vertical paths; and GLS (GBAS Landing System), which uses a Ground-Based Augmentation System to provide GPS-based precision approach guidance. ATC and procedure documents use this combined term when any of the three approach types may be issued or expected.
Plain English
It's a shorthand for the three main types of guided approaches a pilot can fly to line up with the runway: the older radio-beam approach, the GPS-based approach, and the newer GPS-with-ground-correction approach.
Context Anchor
Seen in the AIM, Pilot/Controller Glossary, approach chart notes, and air traffic control discussions of instrument approach operations, especially when more than one type of approach guidance may be in use.
Derivation
The slashes in ILS/RNAV/GLS mean “or” in practical use. They separate three different approach-guidance terms that are being treated as a group for procedures or controller instructions.
Why Pilots Care
The specific system chosen determines the minimum visibility and ceiling required, the type of aircraft equipment needed, and whether vertical guidance is available down to the runway.
Intuition Check
Do not read ILS/RNAV/GLS as one hybrid navigation system. It means ILS, RNAV, or GLS approach guidance, depending on the specific procedure or clearance.
Example Sentence 1
The arrival procedure noted that ILS/RNAV/GLS approaches were all available to Runway 27, so the crew briefed the RNAV as their primary.
Example Sentence 2
Our aircraft is equipped for GLS, so we can use the lower minimums listed under the ILS/RNAV/GLS section of the chart.