Definition
A scanning error in instrument flying in which the pilot fails to look at, or check, an instrument that should be included in the regular cross-check, resulting in incomplete information about the aircraft's state.
Plain English
Leaving an instrument out of your scan. You skip checking it, so you miss what it is telling you.
Context Anchor
Seen in instrument flying discussions about maintaining a steady scan of the instruments and avoiding mistakes during high-workload flying.
Derivation
From the Latin omittere, meaning 'to leave out or let go.' An omission error is literally an error of leaving something out — in this case, an instrument left out of the scan.
Why Pilots Care
Omission errors can leave the aircraft in an incorrect configuration or skip critical safety steps, directly raising the chance of an incident or accident.
Intuition Check
An omission error is not just a paperwork mistake or a general oversight. Here it means a flying mistake caused by leaving out part of the instrument check or control process.
Example Sentence 1
During the checkride, the instructor noted an omission error when the pilot stopped including the heading indicator in the scan and slowly drifted off course.
Example Sentence 2
During the ILS approach, an omission error caused the crew to miss calling the final approach fix.