Mode S
A transponder mode in which each aircraft has a unique 24-bit address, allowing it to be interrogated individually.
Also written
mode select
Mode S ended the need to interrogate every aircraft in a beam at once and added a data link carrying identity, altitude and more. The 24-bit address is the ICAO hex code — the same identifier TailzIN stores as an aircraft's icao24 — and it stays with the airframe rather than the flight.
Nearby in Aviation
- METAR — The routine coded weather observation issued for an aerodrome, normally every half hour or hour.
- missed approach — The published procedure flown when an approach cannot be continued to a landing.
- MTOW — The heaviest an aircraft is certified to be at the start of its takeoff roll.
- narrowbody — An airliner with a single-aisle cabin, typically three to four metres across.