Army Neptunes

We mentioned in an earlier post that the Army operated surplus Navy P-2 Neptunes during the Vietnam War. The Army Security Agency was tasked to collect and analyze signals and electronic intelligence in theater. Basically, that meant they were listening in on as many enemy radio conversations as possible. To overcome the line-of-sight limitation of radio, cover the largest possible area, and reduce the risks to small remote outposts, the decision was made to use airborne radio intercept in Vietnam. One key component to the success of any program would be on-station endurance. And if you want an airplane that had long endurance, the P-2 Neptune was the place to look.  12-14 hour missions were normal. And in 1947, an early production aircraft had made an epic flight from Australia to Ohio, over 11,000 miles, and a record setting 55 hours without refueling.  So, clearly, the Neptune was capable of staying up for quite some time.

The Army took half a dozen SP-2Es, stripped them of their radar and anti-submarine equipment, and installed a battery of radio receivers and tape drives. Newly christened the RP-2E, these spy planes were assigned to the 1st Radio Research Company (Aviation) and flew with ASA crews aboard.


Nicknamed the Crazy Cats, the 1st RRC served operated from Cam Rahn Bay from mid-1967 until 1972. During that time, the company didn’t lose any aircraft, though one was damaged by 37mm anti-aircraft fire.

Another electronic reconnaissance variant of the Neptune wasn’t as fortunate. Owned by the CIA, but operated by the Republic of China’s Air Force, seven P2V-7U/RB-69A electronic ferret birds were built, but all were eventually lost during operations, mostly shot down while overflying mainland Red China to gather intel in their air defense systems.

One final type of Neptune merits mention, as it is sometimes confused with the OP-2E or RP-2E (which, you can kinda guess why…). The AP-2H was a modification of four late model Neptunes to truck-hunters for the Ho Chi Mihn trail. Equipped with Low-Light Television (LLTV),  infrared sensors, radar, and an ignition coil detector, they were an early part of what became knows as TRIM- Trails, Roads, Interdiction, Multisensor. By using multiple sensors, one aircraft was more likely to spot Vietnamese traffic on the trail than an aircraft only using one. You A-6 Intruder fans out there might remember the A-6C was a TRIM bird.  The AP-2Hs were armed with miniguns and grenade launchers to attack any trucking found. Only in service with  Navy squadron VAH-21, they were withdrawn from Vietnam after only a few months. The concept of multiple sensors was validated, and the Air Force would use similar technology with great success with their AC-119K and AC-130A gunships.