Definition
A cross-check error in which the pilot fails to include one or more flight instruments in the systematic scan, leaving a gap in the information used to control the aircraft. Common examples include neglecting the heading indicator during a climb, or ignoring the slip/skid indicator during a turn.
Plain English
Leaving an instrument out of your scan. Your eyes skip over it, so you stop getting information from it without realising.
Context Anchor
Seen in instrument flying when learning common errors in the instrument scan, especially while using traditional round-dial instruments.
Derivation
From the Latin omittere, meaning 'to let go' or 'to leave out.' In instrument flying, it captures the idea that the pilot has unintentionally let an instrument drop out of the scan.
Why Pilots Care
An omission leaves the pilot without critical flight information, increasing the chance of altitude or heading deviations.
Intuition Check
Do not read omission as just a general mistake or a forgotten task. In this context, it specifically means leaving a needed instrument out of the cross-check.
Example Sentence 1
During the post-flight debrief, the instructor pointed out that omission of the heading indicator during the climb had caused the slow drift off the assigned heading.
Example Sentence 2
The instructor noted an omission of the vertical speed indicator that delayed recognition of a climb.