Plain English Meaning

It is a holding pattern shown on an approach chart that the pilot flies as a way to turn the aircraft around so it can line up with the final approach course. The pattern takes the place of a procedure turn.

Full Definition

A charted holding pattern used in place of a standard procedure turn to accomplish course reversal on an instrument approach. The aircraft enters the holding pattern at the designated fix, completes the necessary turns to reverse course and lose altitude if required, then proceeds inbound on the final approach course. Unlike a standard holding pattern used for delay, the HILO is flown as part of the approach itself, and a is normally expected to make only one unless additional time is needed and has been advised.