FAR / AIM: Federal Aviation Regulations / Airmans Information
Manual, 1994 1/2, Jeppesen Sanderson
4. An aircrafts LORAN receiver must recognize
three signal conditions: (1) usable signals, (2) absence of signals,
and (3) signal Blink. The most critical phase of flight is during
the approach to landing at an airport. During the approach phase the
receiver must detect a lost signal, or a signal Blink, within 10 seconds
of the occurrence and warn the pilot of the event.