Plain English Meaning

The aircraft's onboard computer automatically sends a digital message each time the airplane passes a waypoint, so the crew does not have to read out position reports on the radio.

Full Definition

An automated position reporting method in which the aircraft's Flight Management Computer (FMC) generates waypoint passage reports and transmits them via the Aircraft Communications Addressing and Reporting System (ACARS) datalink to air traffic control or the operator, instead of the crew making voice position reports over the radio.