I can identify and certainly hope you bounce back quickly Butch, a mild stroke ended my flying two years ago.
As for emergency air on hookah:
Some of that depends on what you're doing and what kind of equipment you're diving with. On the dredges out west, we usually use no pony bottle (emergency air), because an accumulator is built into the system:
5" Keene Gold Dredge:
Proline 4" Gold Dredge
http://www.prolinemining.com/4_dredge.html
Keene system (same one used on dredges -- same base plate, same hose setup, minus the pump (that runs the dredge nozzle), set inside a tub inside a tractor inner tube:
The air hose comes out of the pump and attaches to a reserve air tank which pressurizes and floats on the surface of the water, cooling the air:
A second hose goes from the tank to your regulator. In the event of engine stoppage (common while working), the reserve tank gives ample time to get to the surface. Engine stoppage is not due to unreliability, but usually because someone shuts it off (your dredge partner is: cold, hungry, wet, wants to go home, shuts down to add gasoline, etc.,).
The Brownie System:
A direct-drive pump mated to the engine supplies air directly to the regulator. Emergency air is supplied via a micro-pony ("spare air") bottle incorporated into your weight belt with a line to a second regulator (so it's a redundant system). Many dive without the "spare air" bottle while on the Brownie and have done so for years (lobster divers using the Brownie 390's).
The Brownie 390 (3 divers to 90 feet)
Cumberbund belt (spare air cyl slips into pouch on front if you want that) -- Engine tote box -- direct-drive compressor)
Air tube for compressor (doubles as flag-stand) -- air fittings are push & click -- same inner tube type setup as Keene for engine/comp.
I dive with both systems (just depends on whether I'm out west or here at home (Brownie here).