You don't have to get "re-dispatched" for a diversion, ATB, or emergency.
If you decide to divert or do an air turnback without declaring an emergency, I would suggest that it would be extremely wise to coordinate with your dispatcher under Part 121 rules these days. Just my opinion.
I'll agree that you don't have to be re-dispatched to proceed to a listed alternate for weather.
I understand the CYA stuff...but seriously, if someone would give them a hard time for returning to JFK without getting re-dispatched, they need to get their heads checked. Decades ago I was taught that declaring an emergency means "grave and imminent danger to the aircraft or lives", and that tying up scarce resources is not a good practice if there is no such grave and imminent danger. But maybe I'm naive.
It sounds nutty and in some cases changes nothing from a safety standpoint, but the latest guidance we are given is when in doubt, declare the emergency. Maybe it comes from our OI (the person formerly known as the POI). It's a compliance thing, the thinking is that if you deviated from your dispatched route using your captain's authority in an emergency situation, why didn't you declare an emergency if you claim to have had an emergency situation?
Here's a reference:
§ 121.557 Emergencies: Domestic and flag operations.
(a) In an emergency situation that requires immediate decision and action the pilot in command may take any action that he considers necessary under the circumstances. In such a case he may deviate from prescribed operations procedures and methods, weather minimums, and this chapter, to the extent required in the interests of safety.
A single hydraulic failure, out of three, in itself would have me run the check-list and then ask the Senior Cabin attendant what's for Dinner .
Again, I'd be less inclined to continue across the pond like that than in years past. And, if you're going to lose a hydraulic system on a '75, I would say the left system is the worst one to do without. But, it's been a long time since I took the oral...
I realize that the Aer Lingus wet lease was not operated under an FAA certificate and there may have been some incentive not to declare an emergency under their operating rules.
But yes, I would have declared an emergency in this case. At least the trucks were already there to quickly put out the wheel fire on landing.
