DATA LINK ACCESS FOR AIRCRAFT SYSTEM
TO SWITCH AIRCRAFT FROM ONE FREQUENCY TO THE OTHER WHILE ENROUTE, VHF MULTI FREQUENCY MANAGEMENT SYSTEM (VMMS) IS USED WHICH AUTOTUNES THE AIRBORNE SYSTEM
VMMS RECEIVES COPIES OF AIRCRAFT FLIGHT MOVEMENT MESSAGES TO IDENTIFY WHEN THE AIRCRAFT IS AIRBORNE AND SHOULD USE THE ENROUTE FREQUENCY AND WHEN IT IS ON GROUND SHOULD USE AIRPORT FREQUENCY
AEEC 620 PROTOCOL SUPPORTS EXCHANGE OF MESSAGES CONTAINING APPLICATION DATA ENCODED AS CHARACTER. USES A 2 CHARACTER ACARS LABEL ON AIR GROUND CONNECTION AND 3 CHARACTER STANDARD MESSAGE IDENTIFIER (SMI) ON THE INTERFACE TO GROUND SYSTEM