Definition
The vertical structural members of an airplane's cabin frame that form the sides of the door opening, providing structural strength to the fuselage and serving as anchor points for the door, hinges, latches, and surrounding cabin structure.
Plain English
The upright frame pieces on either side of an airplane's cabin door. They are part of the airplane's structure and help hold the door in place.
Context Anchor
Seen in safety and traffic-scanning discussions, where doorposts may block a small part of the pilot’s outside view.
Derivation
From the everyday English term for the upright posts framing a doorway in a building. In aviation it carries the same basic image -- the vertical frame around the door -- but applied to the airplane's cabin structure.
Why Pilots Care
Provides a reliable, no-instrument reference that helps maintain exact control authority and prevents over- or under-banking during sideslip maneuvers.
Intuition Check
Do not think of doorposts as the door itself. In this context, they are the fixed upright structure around the door, and they can block part of what the pilot sees outside.
Example Sentence 1
The shoulder harness was anchored to a reinforced point near the doorpost.
Example Sentence 2
To clear the blind spot created by the left doorpost, the pilot leaned forward slightly before turning final.