Answer:

airspace

Answer	Crossword Clue
AIRSPACE	Region that may be restricted
AIRSPACE	Pilots' region of the sky
AIRSPACE	Fly zone

AIRSPACE	NORAD's concern
AIRSPACE	Room for certain traffic.
AIRSPACE	Area protected by military planes
AIRSPACE	It's guarded by military planes
AIRSPACE	Flying zone
AIRSPACE	Pilot's zone
AIRSPACE	Planes need permission to enter it
AIRSPACE	It's flown in

AIRSPACE	Valuable commodity in New York City
AIRSPACE	Flight zone