History: What Were The Primary Uses Of The C-9 Nightingale In The US Air Force?

The McDonnell Douglas C-9 is a retired military variant of the DC-9 commercial airliner. The type was produced in two major variants: the C-9A Nightingale for the United States Air Force (USAF) and the C-9B Skytrain II for the US Navy (USN) and US Marine Corps (USMC).