Definition
The set of standards used by procedure designers to determine the minimum vertical and lateral distances an instrument procedure must keep aircraft away from terrain, structures, and other obstructions. These criteria establish required altitudes, climb gradients, and protected airspace dimensions for each segment of an instrument approach, departure, or arrival.
Plain English
The rules used when designing an instrument procedure to make sure the route keeps aircraft a safe distance above and around anything that sticks up from the ground, like terrain, towers, or buildings.
Context Anchor
Seen in instrument procedure design, approach and departure procedure discussions, and explanations of why certain altitudes or climb requirements are published.
Derivation
From Latin obstaculum (something standing in the way) and clarus (clear, free of). 'Criteria' comes from Greek kriterion, meaning a standard for judging. Together: the standards used to judge whether a procedure keeps aircraft safely free of things in the way.
Why Pilots Care
These criteria are what keep published procedures safe; if they are not met, the route is not approved for use.
Grounding Statement
Picture a published path through clouds near rising ground: obstacle clearance criteria are the design rules that keep that path safely above the ground and structures around it.
Intuition Check
Obstacle clearance criteria do not mean the airplane is protected everywhere nearby. They apply to the specific route or procedure area, and only when it is flown as published.
Example Sentence 1
The minimum altitudes on the approach chart are set according to obstacle clearance criteria that protect the aircraft from terrain on either side of the final approach course.
Example Sentence 2
Because the obstacle clearance criteria were satisfied, the departure procedure could be published at the planned climb gradient.