Originally Posted by
Machinbird
I'd really like to hear from someone in the ATC business regarding how they are instructed to handle 7600 squawks. If not classified, it might be instructional.
I suspect that once you move away from your assigned squawk, their procedures now mandate a strong response since they cannot ascertain whether or not there is interference with the flight crew.
Most automated ATM systems will maintain the correlated Identity so going to 77 or 76 will show that the aircraft is squawking emergency but the correlated aircraft identity will be retained on the display. These days there are multiple sources of surveillance information and they are all collated as a 'track' once that has been correlated with a source of identity that identity will be retained against the track. So a loss of secondary radar will mean the correlated primary radar track will retain the data block etc. Remember if you are also supplying Mode S or ADS-B Extended Squitter (effectively the same thing) you are supplying your airframe identity as part of that transmission.