US Air Force risked aircraft and crews to avoid diplomatic embarrassment
By Marcus Boone ·
Aircraft and crews faced potential loss and diplomatic embarrassment because unreliable navigation hardware threatened flights monitoring 27 signatory nations under the 1992 Open Skies Treaty.
The OC-135B is a modified WC-135B, a plane built for watching. Its purpose is defined by the Open Skies Treaty, signed on March 24, 1992, which allows for nearly unrestricted aerial data collection flights over the territories of the United States and 26 other signatory nations. On paper, these flights are intended to "enhance mutual understanding and confidence." In practice, they are unarmed reconnaissance missions that turn the sky into a shared ledger of military movements.
According to the FAS Intelligence Resource Program mirror, the OC-135B is stripped of the pretense of combat and instead loaded with sensors. The aircraft is designed to provide every participating country, regardless of its size or power, a direct role in gathering information on military forces and activities that cause them concern. This is the official narrative: a tool for stability through transparency. Yet, the hardware itself tells a more familiar story of intelligence gathering, utilizing a platform already steeped in the history of atmospheric and electronic spying.
Four cameras in the rear
The physical transformation of the WC-135B into the OC-135B focused on the acquisition of imagery. The FAS mirror describes modifications that centered around "four cameras installed in the rear of the aircraft." To ensure these cameras could function, the Air Force installed an auxiliary power unit, a sensor operator console, and a flight following console. These additions, along with upgraded avionics and a crew luggage compartment, converted a weather-reconnaissance airframe into a treaty-compliant observation platform.
Public records indicate that the first operationally-capable OC-135B was assigned to the 24th Reconnaissance Squadron at Offutt Air Force Base in October 1993. By the end of 1996, two more aircraft had been delivered. While the treaty limits sensor resolution and distance to maintain a semblance of fairness, the OC-135B remains a sophisticated piece of military hardware. It carries an infrared line scanner, synthetic aperture radar, and video scanning sensors—equipment that allows the operator to see far more than a simple "confidence building" exercise might suggest.
Offutt AFB, Nebraska
Despite the sophisticated imagery suite, the OC-135B was plagued by a mundane, dangerous failure in its navigation hardware. The FAS mirror records a critical vulnerability: the existing Automatic Direction Finder (ADF), the DFA-70, was "rapidly becoming no longer reliable and maintainable."
This was not a minor technical glitch; it was a diplomatic liability. Because many of the signatory nations rely on non-directional beacons (NDBs) for navigation and instrument approaches, the OC-135s required highly accurate ADFs to ensure safe operations. The Air Force warned that without a replacement, there existed a "significant risk of Air Traffic Control violations with resultant diplomatic embarrasment, and potential loss of aircraft and crew."
There is a sharp irony in the record. The same government that spent decades perfecting the art of the covert intrusion was suddenly terrified of a navigation error that might lead to a public, clumsy violation of foreign airspace. The solution was to strip a more reliable system—the Collins ARN-149(V)-2—from the RC-135, the quintessential electronic intelligence aircraft, and install it on the OC-135. The "confidence building" mission was effectively saved by the hardware of the spy plane.
1955 Geneva Conference
The Open Skies concept was not a product of the post-Cold War thaw, but a ghost of the early nuclear age. The FAS mirror notes that President Dwight Eisenhower first proposed the idea to Soviet Premier Nikita Khrushchev at the 1955 Geneva Conference. The Soviets rejected it immediately, and the proposal lay dormant for a generation. It was only in May 1989 that the US reintroduced the idea, framing it as an instrument of confidence building as the Soviet bloc began to fracture.
While the 1992 treaty eventually brought NATO countries, Russia, Ukraine, Belarus, and others into a shared regime of aerial observation, the underlying tension remains. The record shows that Japan, South Korea, Australia, and several Middle Eastern nations expressed interest in the program, expanding the reach of this "mutual understanding."
Other archives, including the NSArchive at George Washington University and the Internet Archive, hold related records on the Office of the Director of National Intelligence's threat assessments and the CIA's Source Evaluation Board for civil space remote sensing, suggesting that the OC-135B was only one piece of a much larger, more aggressive remote-sensing strategy.
The FAS record concludes with a direct demand: replace the DFA-70 with the Collins ARN-149(V)-2 to prevent the loss of aircraft and crew. The documents leave the final confirmation of the installation to the maintenance logs of the 24th Reconnaissance Squadron.