In aviation, taxi refers to the movement of an aircraft on the ground under its own power. It covers everything between the parking gate and the runway: rolling out to take off, or rolling back to the gate after landing. Taxiing excludes the takeoff roll and the landing rollout themselves, so it’s strictly a ground-travel phase.
How Taxiing Works
For a departing flight, the taxi phase begins at or near the aircraft’s parking stand on the apron and ends at the runway holding position, where the plane waits for clearance to enter the runway. For arriving flights, taxiing starts once the aircraft has slowed sufficiently after landing and continues until it reaches its assigned parking stand. Pilots also taxi to reposition an aircraft from one part of the airport to another, such as moving between a terminal and a maintenance hangar.
Most commercial and general aviation aircraft taxi using their own engines at low power. Pilots steer with a combination of a tiller (a small steering wheel in the cockpit that turns the nose wheel), rudder pedals, and differential braking. Typical taxi speeds range from about 10 to 20 knots, though airports may impose lower limits in congested areas.
Taxiing is distinct from pushback, which happens before taxi on departure. During pushback, a tug vehicle physically pushes the aircraft backward away from the gate because jet engines can’t safely reverse at a terminal. Once the pushback is complete and engines are running, the pilot takes over and begins taxiing. Tow vehicles also move aircraft between gates and maintenance hangars, but those operations require separate clearance from the control tower and aren’t considered taxiing since the aircraft isn’t moving under its own power.
Helicopter Air-Taxiing
Helicopters and other vertical-takeoff aircraft have their own version. Air-taxiing means hovering above the airport surface, typically in ground effect, at a ground speed below 20 knots. It serves the same purpose as conventional taxiing but takes advantage of a helicopter’s ability to move without wheels on the ground.
Taxiway Markings and Lights
Airports use a standardized system of painted lines, signs, and colored lights so pilots can navigate safely on the ground, even in poor visibility.
The taxiway centerline is a single continuous yellow line, either 6 or 12 inches wide, that pilots follow to stay on the designated path. At larger commercial airports, you’ll also see enhanced centerlines: a pair of yellow dashed lines flanking the normal centerline for up to 150 feet before a runway holding position. These extra dashes warn pilots they’re approaching a point where they need to stop unless cleared onto the runway.
Taxiway edges are marked with continuous double yellow lines when the adjacent pavement isn’t meant for aircraft (like a shoulder). Where the neighboring surface is usable, such as an apron, the edge lines switch to dashed double yellow lines.
Signs at holding positions use a red background with white text. These mandatory instruction signs mark entrances to runways and restricted areas. Some are also painted directly on the pavement surface as a backup.
At night or in low visibility, colored lights take over. Taxiway edge lights glow blue, making it easy to distinguish taxiways from runways (which use white edge lights). Taxiway centerline lights emit steady green. Where a taxiway leads off a runway, alternating green and yellow lights guide pilots from the runway centerline past the holding position, signaling they’re transitioning out of the runway environment.
What Pilots Do During Taxi
Taxiing is classified as a critical phase of flight. Under the sterile cockpit rule, enacted by the FAA in 1981, crew members are prohibited from performing non-essential duties or activities during taxi, takeoff, landing, and all flight operations below 10,000 feet (except cruise). That means no casual conversation, no paperwork unrelated to the current operation, and no distractions. The rule exists because a significant number of accidents and incidents were traced back to crew members losing situational awareness during these phases.
Before moving, pilots receive a taxi clearance from ground control that specifies an exact route: which taxiways to use, where to hold, and which runway to expect. Pilots read back the clearance to confirm they understood it correctly. At busy airports, taxi routes can be surprisingly complex, involving multiple turns, crossing active runways, and holding at several points along the way.
One of the biggest risks during taxi is a runway incursion, which occurs when an aircraft, vehicle, or person enters an active runway without authorization. Many pilot errors during taxi happen when one or more crew members are off-frequency or doing heads-down work like programming a GPS or flight management system. Standard operating procedures emphasize keeping eyes outside the cockpit and maintaining a listening watch on the radio whenever the aircraft is in motion.
How Long Taxiing Takes
Taxi times vary enormously depending on the airport. At a small regional airport, you might taxi for two or three minutes. At a major hub like Atlanta, Dallas-Fort Worth, or Chicago O’Hare, taxi times of 15 to 30 minutes are common, and delays can push that even longer during peak traffic. Airlines factor expected taxi times into their schedules, and the time between leaving the gate and wheels-up is one of the metrics used to track on-time performance.
Fuel burn during taxi is real. A large commercial jet can burn several hundred pounds of fuel just getting to the runway. Some airlines use single-engine taxi procedures, shutting down one engine during ground movement and starting it before reaching the runway, to reduce fuel consumption and emissions.