When does a plane depart? NZ pilot explains the departure time

Considering the havoc a delayed flight can cause for travellers, crew and other flights, the definition of when a plane officially departs is very important.

Is the official departure time when the doors are locked, or when the aircraft pulls away from the gate? Is it when the plane starts moving down the runway or when the wheels leave the ground?

According to Air New Zealand pilot Captain David Morgan there are several specific stages.

“The actual time of departure is when the front door is shut and the parking brake is released and at that point, it’s called ‘out’. You’re out, you’re moving off the gate,” he said.

At this moment, a signal is sent to an external system that announces the plane is ‘out’.

So, on airline schedules, ‘departure time’ is when the aircraft door is closed and the parking brake is released.

When an aircraft becomes airborne and the weight is off the wheels, you’re ‘off’, Morgan said.

On arrival, it’s similar but in reverse.

“The next one is ‘on’ when you touch down and ‘in’ is when the parking brake is set and the front door has been opened,” Morgan said.

According to the International Civil Aviation Organisation (ICAO), flight time is defined as “the total time from the moment an aeroplane first moves for the purpose of taking off until the moment it finally comes to rest at the end of the flight”.

This includes any time the aircraft spends taxiing or completing pre-flight checks if the engine is running.

It defines “air time” as “the time from the moment an aircraft leaves the surface until it comes into contact with the surface at the next point of landing”.