What's easier than I think?
Originally Posted by VideoPaul
You turn the first two dials through to 4 and 6 but pass 7 and 5 on the way around. If the transponder is polled by the radar at the exact wrong moment, you will send 7500.
Most transponders are bidirectional so you can go from 5 to 2 without bypassing 7. I believe someone thought it was a button pushed in the plane and I'm glad you brought this up as the button thing is incorrect.
Alarms go off at ATC facilities, all kinds of nonsense breaks loose.
No, that's not the case. There are no alarms. Controller asks pilot to "Confirm squawk 7500." If there is silence, confirmation or if it's NORDO, well it's going to be assumed a hijacking is in progress. If he negates and switches the transponder it's not much of an issue. In this case, pilot apparently negated but continued to squawk 7500. The only change since 9/11 is if the pilot negated, controllers monitor that flight more carefully and are quick to note if it deviates from course or does anything strange. In that case, there are phone calls that get made ...
A bit of a problem is that everyone in the world can easily know the emergency squawk codes and the procedures for negating them. It's tough to keep it much of a secret when there are tens of thousands of pilots using the same system worldwide.
Most ATC facilities are making tours available again. If you're interested in learning more about ATC, you might want to contact Chicago Center about a tour.