"Can someone from European/UK ATC advise us whether or not you want an aircraft in a rapid [unplanned] descent to squawk 7700?
Our training department is saying in Europe, ATC don't want us to change the assigned code in an emergency descent, it would "cause more problems" and you "can see we are in descent"
Thanks"
European airspace is increasingly being divided vertically, often between different agencies. Squawking 7700 will alert all the underlying sectors and burn through any filtering in place. Squawking 7700 will also facilitate co-ordination between sectors and units as the emergency A/C is easily identifiable.
The perception that it may cause more problems came from the tendency of older processers to drop the callsign of the emergency aircraft. London FIR Area Radar units will not lose the A/Cs identity if an emergency code is selected. I cannot vouch for the rest of Europe but as most of Western Europe has newer kit than us I cannot imagine they would suffer the loss of callsign either.