1. Because Angel Flights get slightly higher priority in routing if
needed and



Lifeguard is given priority handling by ATC, Angel Flight is not.


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Officially, you are correct. Unofficially, Angel Flights are treated
with a special (and detectable) "consideration".



2. To give the controller information about the flight that might help
in an emergency.



How would knowing a VFR GPS was aboard help the controller in an
emergency?

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It seems to me that what kind of navigational equipment the pilot has
on board is "relevant to the flight", and I can think of scenarios
where knowing the pilot has a GPS might help in an emergency involving
failure of one or more instruments, or partial electrical failure. Let
me ask you, Steven, how could it HURT the controller to have this
information?