Definition
An instrument approach procedure that provides lateral course guidance to the runway but no vertical guidance meeting precision approach standards. Examples include VOR, NDB, LOC, and most basic RNAV (GPS) LNAV approaches. The pilot is given a final approach course to fly, but must manage descent to the minimum descent altitude (MDA) using published step-down fixes and altitudes rather than a continuously guided glidepath.
Plain English
An instrument approach where the navigation system tells you the direction to fly toward the runway but does not give you a vertical path down. You handle the descent yourself, using published altitudes, until you reach the lowest altitude allowed without seeing the runway.
Context Anchor
Seen in instrument approach procedures, especially when planning or flying the final approach segment without a glidepath or glideslope.
Derivation
‘Nonprecision’ literally means ‘not precision.’ A precision approach is defined by ICAO as one providing both lateral and vertical guidance to specified standards. Removing the vertical-guidance element gives you a nonprecision approach — hence the name.
Why Pilots Care
Pilots must manually calculate descent points using step-down altitudes, timing, or distance, raising workload and the chance of flying too low too soon.
Intuition Check
Do not read “nonprecision” as “not accurate.” Here it means “no approved vertical guidance is provided,” not “the course guidance is poor.”
Example Sentence 1
Because the localizer was out of service, the crew briefed the VOR approach as a nonprecision approach with an MDA of 1,180 feet.
Example Sentence 2
Because the airport had only an NPA available that night, the crew timed the approach from the fix to know when to go around.