Definition
A precision instrument approach system that uses GPS signals, augmented by a local ground-based correction station at the airport, to provide pilots with lateral and vertical guidance to the runway. The ground station broadcasts correction data and approach path information to the aircraft via VHF data link, allowing the aircraft's onboard equipment to compute a precise approach path comparable in accuracy to an Instrument Landing System (ILS).
Plain English
A landing system that uses satellite signals, made more accurate by a small correction station at the airport, to guide the aircraft down to the runway with both side-to-side and up-and-down guidance.
Context Anchor
Seen on an instrument approach chart when a runway has a published GLS approach, and selected in the aircraft's approach or navigation equipment before flying it.
Derivation
Called 'global' because it uses the global satellite navigation system (GPS) as its core source of position data, and 'landing system' because the airport-based correction station turns those satellite signals into a precise approach guidance system for landing.
Why Pilots Care
It enables precision approaches at airports without traditional ILS equipment, increasing access to lower landing minimums.
Intuition Check
Global does not mean a pilot can use it to land anywhere in the world. A GLS approach is available only where that specific runway has the published procedure and supporting equipment.
Example Sentence 1
The crew briefed the GLS approach to runway 27, noting the published minimums were similar to those of an ILS.
Example Sentence 2
After loading the GLS procedure, the aircraft captured the glidepath and began the stabilized descent.