The schedule measures a whole trip, not just flight
A published flight time is usually a gate-to-gate estimate: it starts when the aircraft leaves its departure gate and ends when it reaches the arrival gate. The plane may be airborne for less time than the schedule suggests. Taxiing, waiting for a runway, and holding for a place to land all count toward the passenger’s trip—and can vary sharply from one day to another.
That variability is especially costly at crowded airports. A departure delayed on the ground can also disrupt later flights: the same aircraft may be due to carry another group of passengers, while its crew and gate are needed elsewhere. Airlines therefore plan around the airport system, not merely the distance between two cities.
Why airlines build time into the plan
Airlines add schedule margin—often called padding—to account for routine delays. If a flight is scheduled too tightly, ordinary congestion can make it arrive late even when the flight itself runs smoothly. A longer published time gives the operation room to absorb some of that uncertainty and makes the airline’s on-time record less vulnerable to small disruptions.
This creates a tradeoff. More scheduled time can improve the odds that a flight arrives by its published time, but it also makes the itinerary look longer and may leave passengers waiting after an early arrival for a gate to open. A comparison with flights from decades ago can therefore reflect changes in taxiing, congestion, and scheduling practices—not a simple change in how fast the aircraft flies.
The clock passengers see is partly a record of what the airport can reliably handle, not just a measure of the airplane’s speed.
