Hi Flying Wild
Until recently, Sq 1000 and Mode S identification was only used for flights operating entirely within airspace that could handle it, so between FRA/MUC/AMS/CDG and operating with Maastricht/Rhein/Reims/Paris/Amsterdam/Langen/Munich ACCs.
What has changed recently, is that Sq 1000 is now being issued to aircraft mid-flight that were previously correlated on a Mode A code. Once the Mode A code is no longer needed because all of the remaining units along the route of flights are Mode S equipped, then the Mode S can be used, Sq 1000 issued, and the Mode A code released for use again.
Maastricht are now using this procedure for aircraft that must have a squawk change anyway. So for example, aircraft coming in from Scandinavia, that is in a different code allocation PA, have to have their squawk changed coming southbound. This will now be 1000 for those going to suitable airports.
Flights that depart from within the Mode S area, but are leaving it, will be given a normal Mode A code from the start because otherwise they would have to have it changed as they approached the boundary with the non Mode S equipped ACCs.
At present, aircraft that are correlated using a Mode A code, but are not required to change, for example flights from the UK into Europe, are being left on that Mode A code, to prevent an increase in workload.
Eg.
Flight ARN-FRA
- Mode A allocated on departure, for use by Sweden and Copenhagen
- Must have a squawk change on transfer from Copenhagen to Maastricht, remaining units are Mode S capable, so given Sq 1000.
Return flight FRA-ARN
- Must be on a discrete Mode A code on transfer from Maastricht to Copenhagen, so given a Mode A code from the start.
Flight LHR-MUC
- Although on transfer from LACC to Maastricht, the remaining units are all Mode S capable, Sq 1000 could therefore be used, this flight stays within the same code allocation area, so no change is necessary, so it is left as it is on the original Mode A code.
Were you by any chance headed for Prague? If so, then I think a squawk change is needed when you go from Germany to the Czech Republic, which is why the 1000 was given by Rhein going eastbound.
Last edited by GlobalJourney; 7th May 2012 at 19:40.