Block Flying Time
Block flying time is a term used to identify the duration of the trip. Block time officially starts when the aircraft first moves from its parking place and ends when the aircraft reaches a designated parking position with all engines stopped.
If, according to the flight plan, the flight from point A to point B will take three hours and twelve minutes, the block flying time estimation will be fixed to compensate for the time that will be spent pushing back from the gate, taxiing to the runway, and waiting to park at the destination airport. This way we can know exactly how long to plan for time en route, to maximize even those first and last half-hour periods of potential laptop work that could otherwise be lost.
At any airport there can be a large volume of aircraft movement and ground operation going on simultaneously and, since safety is always the top priority, the flight crew plans accordingly. By scheduling block flying time, enough time is allotted between first movement and actual lift-off so that safety corners are not cut by otherwise rushing to the runway to begin.