Introducing the GHA 15 Height Advisor for Certified Aircraft

OLATHE, Kan./Feb. 4, 2026 –

Garmin today announced the availability of the GHA 15 height advisor. Previously approved only for experimental aircraft, the GHA 15 is a small and lightweight height advisor that uses radar technology to provide height above ground level (AGL) information. The GHA 15 for certified aircraft can display height AGL on compatible GI 275 electronic flight instruments¹. The Federal Aviation Administration (FAA) has granted Supplemental Type Certificate (STC) approval for the installation of GHA 15 in more than 500 certified class I & II aircraft.

The GHA 15 calculates height AGL by sending radio waves to the ground and determining the time it takes to receive the signals back. It processes hundreds of measurements per second and applies advanced digital filters to maintain continuous readings – even over water or in challenging terrain environments. AGL readouts are shown on the GI 275 electronic flight instrument1 at altitudes as high as 500 feet AGL.

Using the readings provided by the GHA 15, the GI 275 can also provide AGL audio callouts² to help keep the pilot’s eyes looking outside the cockpit. Beginning at 300 feet, the pilot will hear audible AGL altitude callouts at select intervals down to 1 foot AGL. The pilot can configure the callouts to start and stop at specified altitudes. Knowing precise height AGL can be helpful to pilots during landings and flying in areas where limited barometric altimeter setting information is available – such as backcountry flying.³

The single module integrates all electronics into one compact unit that attaches to the bottom of the aircraft. Slightly larger than a deck of cards and weighing less than one pound, the height advisor requires minimal space and modification for installation on the aircraft.

¹ Digital readouts will display only on GI 275 ADI, HSI, MFD & standby ADI variants. GI 275 ADAHRS equipped model required.
² Provided through GI 275 audio output; compatible audio panel, intercom or headset required.
³ GHA 15 provides advisory information and may not be used for decision altitude or decision height in IFR conditions.