Taxiway (TWY)

What Is a Taxiway?

A taxiway (TWY) is a defined paved route on an airport that allows aircraft to travel safely between runways, terminal gates, hangars, and the apron. Without an organised taxiway system, aircraft would need to use active runways for all surface movement — a dangerous and inefficient arrangement. Taxiways are identified by alpha or alpha-numeric designators (e.g., Alpha, Bravo, Taxiway A3) displayed on blue signs with yellow lettering.

How It Works

Air Traffic Control issues taxi clearances specifying the exact taxiway route an aircraft must follow. Pilots read back the instructions to confirm understanding. Yellow centreline markings guide pilots along the correct path, while hold-short lines — two solid and two dashed yellow stripes — mark the boundary beyond which an aircraft must not proceed without explicit ATC clearance. Blue edge lights and green centreline lights illuminate taxiways at night or in low visibility. Incursion prevention systems at major airports use surface detection radar and automated stop-bar lights to prevent aircraft from crossing active runways without clearance.

Types and Standards

• Parallel taxiways: Run alongside runways, keeping traffic well clear of active surfaces. Standard at busy airports.
• Rapid exit taxiways (RETs): Angle off the runway at approximately 30°, allowing aircraft to exit at higher speeds (≈93 km/h) and free the runway faster.
• Apron taxiways: Lower-speed paths within the apron area, often shared with ground vehicles.
• Taxilanes: Narrow access routes inside aircraft parking areas, not designed for high-speed use.

ICAO sets taxiway width standards by aircraft code letter — Code F aircraft (A380, 777X) require taxiways at least 25 m wide with 7.5 m clearance on each side.

Interesting Facts

• Heathrow uses a complex taxiway layout with Taxiway Alpha running the full length of both runways — aircraft can taxi between terminals without ever crossing an active runway.
• Atlanta Hartsfield-Jackson's taxiway system handles over 2,700 aircraft movements per day, making precise ATC routing essential.
• Taxiway incursions — aircraft or vehicles entering the wrong taxiway or crossing a runway without clearance — are among aviation's most scrutinised safety events.
• Some airports use "virtual" taxiway centreline guidance displayed on cockpit moving-map displays to aid crews in complex, low-visibility conditions.