Close to the village of Effelsberg in western Germany a large radio telescope is operated
for scientific purposes. In order not to interfere with those measurements, Iridium satellite
communication is usually not possible in this area.
The location of the telescope is about 22NM SSW of Cologne Bonn airport EDDK. The large dish
can even be seen clearly on
Google Maps.
The area affected will depend on your flight altitude and also on the current location of
the Iridium satellites and their angle to your position. But from practical experience the
affected area seems to have a radius of at least 10NM. We also have reports that Iridium
communication is not available at the nearby Nürburgring race circuit and a few VFR airfields
in the area.
If you try to use your ADL device while flying in this area you experience a situation which
resembles a bad Iridium signal or antenna issue. But the ADL device will resume communication
as soon as this becomes available again. Usually no human action besides patience is required.
Below you see a few screenshots from a transit through this area at FL290. The final confirmation
are those semicolons in the transmission log. Those will only show in this Effelsberg situation.
A few minutes later the ADL device resumed normal operation. At lower altitudes the affected area
seems to be a little smaller.
