Definition
A perceptual phenomenon in which a pilot or controller hears, sees, or interprets information as what they expected to receive rather than what was actually transmitted or presented. It is a recognized contributor to communication errors, readback/hearback errors, and instrument misinterpretation in aviation human factors.
Plain English
When you expect to hear or see something, your brain can fill it in for you — even if what was actually said or shown was different. You think you got the message right, but you didn't.
Context Anchor
Seen in aviation human factors, cockpit decision-making, radio communication, checklist use, and accident discussions.
Derivation
From Latin expectare, meaning 'to look out for' or 'await.' The aviation use highlights how the act of anticipating something can shape what we perceive, sometimes overriding what is actually there.
Why Pilots Care
Unrecognized expectancy contributes to errors such as failing to notice an altitude deviation, mishearing an ATC instruction, or overlooking an abnormal instrument reading.
Grounding Statement
A pilot may hear, see, or believe the expected answer unless they deliberately check what is actually being presented.
Intuition Check
Expectancy does not just mean “looking forward to something.” In aviation, it means an expectation can influence what a pilot perceives or decides.
Example Sentence 1
Expecting a descent to 7,000 feet, the pilot read back '7,000' even though the controller had assigned 9,000 — a classic case of expectancy.
Example Sentence 2
During the approach briefing the crew discussed how expectancy of a long straight-in could lead to missing an early descent clearance from ATC.