Definition
The time at which a flight is proposed to depart, as filed in the flight plan or as coordinated through air traffic control. P Time is used by ATC for traffic flow planning and for issuing departure clearances and slot times.
Plain English
The time you said you plan to take off, as written in your flight plan. Controllers use it to plan when to fit your flight into the system.
Context Anchor
Seen in flight plans, dispatch information, and air traffic control departure planning.
Derivation
The 'P' simply stands for 'Proposed.' It distinguishes the planned departure time from the actual departure time, which is recorded separately once the aircraft is airborne.
Why Pilots Care
It allows controllers to plan traffic flow and assign departure slots.
Intuition Check
P TIME is not the time the aircraft actually took off. It is the planned departure time given before departure.
Example Sentence 1
We filed a P Time of 1430Z, so we need to be ready for pushback by 1415 to make our slot.