Definition
A ground-based radio navigation system that determines an aircraft's position by measuring the time difference between signals received from a chain of low-frequency transmitter stations. The receiver compares the arrival times of pulses from a master station and one or more secondary stations to compute lines of position, which intersect to give a fix.
Plain English
An older radio navigation system that figures out where you are by timing how long signals take to reach you from several known ground transmitters. Where the timings cross, that's your position.
Context Anchor
Seen in older navigation equipment, older aircraft manuals, FAA glossary material, and discussions of navigation systems that came before modern satellite navigation.
Derivation
From 'Long Range Navigation,' a name chosen during World War II to distinguish it from shorter-range radio systems of the time. The 'long range' part is literal — Loran signals travel hundreds of miles, much farther than VOR or NDB signals.
Why Pilots Care
It once provided dependable long-range navigation over water and remote areas before GPS became the primary system.
Intuition Check
Loran is not GPS. GPS uses satellites; Loran used timed radio signals from fixed stations on the ground.
Example Sentence 1
Before GPS became standard, many general aviation aircraft used Loran for cross-country navigation.
Example Sentence 2
Although GPS has replaced it for most operations, the aircraft checklist still includes a Loran check for redundancy.