There has been some discussion recently about long distance communications, specifically in relation to what could or should have been transmitted from Air France flight 447 before it disappeared on it’s flight from Rio De Janeiro (GIG) to Paris (CDG) on June 1st. There appear to be some misconceptions about what types of communication are used between aircraft and Air Traffic Control and a confusion between Air Traffic Control and radar contact on longhaul flights. I thought a little information about how my international flights are conducted might clear up some of the confusion.
The majority of my flights pass in and out of radar contact several times between take-off and landing. We start out the flight using the VHF radio to talk to Air Traffic Control (ATC). While we are using VHF communications we keep our company updated on our progress by manually sending position reports directly to them using the ACARS datalink system at approximately 90 minute intervals. Eventually we fly out of VHF (line-of-sight) range and switch to the High Frequency (HF) radio for long-range communications. At that point we are also usually out of radar contact. Radar, like VHF communications, is a ground-based and line-of-sight system. Once an aircraft is beyond the reach of the radar signals the separation of aircraft flying on the same route is accomplished through position reporting to an ATC facility.