Definition
A type of instrument approach procedure that provides lateral course guidance to a runway or airport, but does not provide vertical (glidepath) guidance. The pilot uses the instruments to stay aligned with the approach course and steps down through published altitudes until reaching a minimum descent altitude (MDA), from which the runway environment must be seen to continue and land.
Plain English
An instrument approach that tells you where to go left and right, but not how steeply to come down. You follow the course toward the runway and descend in steps to a published minimum altitude. If you can see the runway by then, you land. If not, you go around.
Context Anchor
Seen in airport and runway descriptions, approach planning, and discussions of instrument approaches.
Derivation
Nonprecision' here means 'without precision vertical guidance.' In aviation, 'precision' is a defined category — an approach is only 'precision' if it provides electronic glidepath information (like an ILS). Anything without that vertical guidance is, by definition, 'nonprecision.' The word isn't saying the approach is sloppy or inaccurate.
Why Pilots Care
Affects legal weather minimums, required procedures, and the pilot's workload during the approach.
Intuition Check
Do not read “nonprecision” as “inaccurate.” It means the procedure does not provide the full precision vertical guidance of a precision approach. Do not read “instrument” as just a cockpit gauge; here it means flying by instruments and a published procedure.
Example Sentence 1
The VOR approach into the small field was a nonprecision instrument procedure, so we briefed the step-down altitudes carefully before starting the descent.
Example Sentence 2
Nonprecision instrument approaches usually have higher decision altitudes than precision approaches.