Yesterday flying westbound, first Rhein Radar after Warsaw Control gave us squawk 1000. IFR. Strange thing about it was that also couple other a/c got same code (1000) under same control (1 Lufthansa, 1 LOT and 1 AF). Just wondering, why was this? No more codes available or some kind of new/special procedure?
Both. 1000 is the Mode S Conspicuity Code.
If you are assigned that, it means that the ATC is using your Mode S Aircraft ID (i.e. flight number) to correlate your identity instead of needing a unique Mode A squawk.
The aim is to mitigate the acute shortage of squawk codes.