The CIA, via its contractor Southern Air Transport, operated four 727s during the Vietnam War. These jets were "convertible" from cargo to passenger configurations and featured a cargo door in the forward fuselage. Yet the CIA figured out that they could not only haul cargo and passengers, but they could also drop them as well.
Southern Air Transport worked as somewhat of a shell contractor flying airliners for Air America during the late 1960s, of which the Boeing 727-200C was the most prevalent. As part of this contract, the powers that be wanted to see if these aircraft could be used for clandestine air drops via modifying their built-in rear air stairs with a slippery slide like trough.
Tests were conducted over Thailand in 1968 and the aircraft seemed uniquely capable of quickly air dropping pallets of cargo as well and jumpers while retaining overall airliner appearance and performance. The extent of which this capability was used once it was proven is not clear, but I have been told that it was in fact used repeatedly in Laos and other "border regions" where America was not technically supposed to be.
In 1971, high altitude thief DB Cooper would prove to the world that this capability existed throughout the 727 fleet. Cooper actually lowered the stock rear air stair in flight and jumped from a slow and low flying 727-100 somewhere over southern Washington State, a feat he seemed very confident at executing.
Years later a company called Air Drop Inc. was said to have used a similar configuration as the one tested by the CIA for dropping supplies to "customers" in the African bush. Additionally, other 727s, as well as the DC-9 which also have a rear air stair, have also been used by civilian operators for mass parachute drops.
One has to wonder just how far the CIA may have taken their creative use of the 727's inherent design. It would seem that having a plentiful jet cargo and passenger aircraft, one that could hide in plain site, or should I say airspace, that could have also launched high-altitude, low-opening (HALO) parachute jumpers, would be a massively valuable clandestine asset. This is true not just of the CIA but of the DoD's Special Operations Command (SOCOM) as well.
In fact, when you think about it, the 727 may have been way ahead of its time militarily. Having a commercial aircraft that can fly fast and high while also being able to punch stuff out its empennage seems like the perfect persistent close air support aircraft of today. A "poor man's heavy bomber" if you will.
We have spent a decade and a half fighting wars in the Middle East, where we have burned through billions and billions of dollars via the use of ultra-expensive B-52 and B-1B flight hours, all in an attempt to create an orbiting "arsenal ship" presence over the battlefield. This is not even counting the startling number of precious fast jet hours we have gobbled up during these wars or all the fuel we used keeping these thirsty assets fed. Maybe a group of surplus 727s with a track system installed to release munitions out of their tail apertures, along with racks on either side of the cabin for various guided munitions to be stowed, would have been a much cheaper and expendable solution to this problem.
In the past, dropping munitions out of the back of a C-130 was common. The Vietnam War saw the massive BLU-82 "Daisy Cutter" deployed off its rear ramp. Today we have seen this done to a smaller degree with the latest "Harvest Hawk" and "Dragon Spear" close air support capable C-130Js. These aircraft use primitive munitions cradles and gravity drop versions of the Griffin and Viper Strike air to ground missiles. There has even been talk of deploying a kit that would see JDAMs and other large guided munitions rolled off their rear ramps. Still, a 727 can operate from fairly short fields, especially for a 600mph aircraft, and can respond to different geographical areas as fast as a Harrier or B-52 could, and much faster than a lumbering C-130.
Conceivably a 727 with a cargo track like system installed on its floor could carry multiple types of air to ground munitions, which could be rolled onto the main guide track that terminates at the rear air-stair opening after being programmed for release. In an age where smart munitions are plentiful and can hit with pinpoint accuracy under any weather conditions, does it really matter if their launching aircraft was designed originally as a weapon or not? Hardly. It is all about the weaponry and not the platform when it comes to air combat in permissive airspace.
With all the billions of dollars spent and precious fast jet and bomber air-frame hours since 2001, maybe systems such as a simple 727 (or even more economical MD-80) orbiting arsenal ship should have been looked at more carefully. The fact that it, or another off-the shelf system like it, was never widely proposed, is a signal of just how fiscally near sighted our Defense Department can be even during a time of budget crushing prolonged warfare.
In the end only a handful of 727s were ever operated by the US military under the C-22 designation, and these aircraft were only used for cargo and personnel transport as far as I am aware of. Thus the USAF may have passed up a plentiful, relatively economic and FAA certified airframe with great multi-role potential and little need for modification.
A jet whose unique tactical attributes were so inherently clear that even a crooked hijacker figured it out almost 45 years ago.
USAF C-22 picture courtesy of Felix Goetting via wikicommons