När och varför kontrolleras SELCAL (Selective Calling Radio System)?

Om du är osäker på om din SELCAL-utrustning fungerar korrekt, kan du begära en SELCAL check på en HF-aktiverad radiofrekvens. ATC-enheten skickar ut din SELCAL-kod för teständamål.

I'm not sure my selcal unit is working, is there anywhere I can test it?

Yes, several places. If you are located in:

• Europe or east of 30W on the North Atlantic, call Stockholm Radio
• Eastern USA/Canada or west of 30W on the North Atlantic, call New York ARINC
• Western USA/Canada or Pacific, call San Francisco ARINC
• Asia - daylight hours, call Singapore or Manila Radio on 8942 KHz USB

[...] All selcal checks are free of charge - just call the station with the aircraft registration mark and when you receive a reply ask for a selcal check and give your selcal code. The operator will send out your selcal tone and - assuming the selcal unit is working - you will hear a chime in the cockpit. Acknowledge by replying 'selcal check okay' and you're done! If your selcal check doesn't work the first time it is worthwhile asking for a 'double' which means you get 2 sets of tones sent out back-to-back and often cures any issues.
(Source: www.selcalweb.co.uk)