Reports are given either at designated reporting points or at significant points quoted in the flight plan. Generally reports are made at approximately one-hourly intervals.
The report is given in latitude and longitude. The next position and an estimate of the time at that position is then given, using the next significant point to be crossed by the aircraft. Where the estimate is expected to be incorrect by three minutes or more, the fact should be reported to the ATC centre.
Finally, next position report (without an estimate of time over) is given to ATC to enable a close check to be made on the flight at all times. Position reports consist of the following:
- the word ‘position’
- the aircraft identity
- present position
- time over (in hours and minutes UTC)
- present flight level
- estimated next position (hours and minutes)
- next significant point
- further information - å.g. meteorological or company details
Flights or routes from east to west (or vice versa) are required to give latitude in degrees and minutes, with longitude only in degrees. (Most North Atlantic tracks have waypoints which occur at whole units of latitude and longitude).
If the direction of the flight is from south to north or the opposite, the require-ment is for latitude in degrees, with longitude in degrees and minutes. For example: ‘Swissair One One Zero, Five Two North Two Zero West One Zero Two Zero, Flight Level Three Five Zero, Estimate Five Two North Three Zero West One One Zero Two, Next Five One North Four Zero West’.
The same message can be written as follows:
Swissair 110.
52 North 20 West 10.20 (52°32'20'' N 20°10'26''W)
FL 350
Estimate 52 North 30 West 11.02 (52°42'30'' N 20°20'38'' W)
Next SU.
As the flight approaches the boundary between adjacent oceanic control areas the position report is made to the two centres on the same frequency - e.g. at 30° West the report for a westbound flight would be prefixed ‘Shanwick Speedbird 175 position copy Gander’.
Meteorological information, when required, is transmitted at the end of the message. After the meteorological report the words ‘NIL - NIL - NIL’ may some times be heard. These refer to ‘nil icing, nil turbulence, and nil significant weather’.