Under this treaty foreign observation aircraft enjoy priority over all other aircraft in U.S. airspace - private, commercial and military. The only exceptions are presidential aircraft and declared emergencies. They may fly anywhere between approximately 500 to 5,000 feet for low altitude observation, or 18,000 to 36,000 feet for high altitude observation, the altitude and destination being the choice of the commander of the observing aircraft. The Open Skies Treaty designates the types of sensors that observing aircraft may use in flight. Optical sensors in the form of video, frame and panoramic photography are authorized.
Infrared line scanning devices work well at night and are also approved.
SAR works day or night in any weather, even in heavy rain. It directs a radar beam at the ground in a ten nautical mile swath under the aircraft. The beam bounces back to the aircraft creating a photo-like image in the device. Sandia Labs has developed a special pod containing the SAR sensors and related equipment. The 16-foot pod connects easily under the wing of observing aircraft similar to an external fuel tank.