The initial polyethylene balloons had diameters of only seven feet and carried payloads of five pounds or less.[72] As balloon technology advanced, payload capacities and sizes of balloons increased. Modern polyethylene balloons, some as long as several football fields when on the ground, expand at altitude to volumes large enough to contain many jet airliners. Polyethylene balloons flown by the U.S. Air Force have reached altitudes of 170,000 feet and lifted payloads of 15,000 pounds.[73] During the late 1940’s and 1950’s, a characteristic associated with the large, newly invented, polyethylene balloons, was that they were often misidentified as flying saucers.[74] During this period, polyethylene balloons launched from Holloman AFB, generated flying saucer reports on nearly every flight.[75] There were so many reports that police, broadcast radio, and newspaper accounts of these sightings were used by Holloman technicians to supplement early balloon tracking techniques.[76] Balloons launched at Holloman AFB generated an especially high number of reports due to the excellent visibility in the New Mexico region. Also, the balloons, flown at altitudes of approximately 100,000 feet, were illuminated before the earth during the periods just after sunset and just before sunrise. In this instance, receiving sunlight before the earth, the plastic balloons appeared as large bright objects against a dark sky. Also, with the refractive and translucent qualities of polyethylene, the balloons appeared to change color, size, and shape. The large balloons generated UFO reports based on their radar tracks.[77] This was due to large metallic payloads that weighed up to several tons and echoed radar returns not usually associated with balloons. In later years, balloons were equipped with altitude and position reporting transponders and strobe lights that greatly diminished the numbers of both visual and radar UFO sightings. One classic misidentification of a Holloman balloon that was mistaken for a UFO, was launched on October 27, 1953.[78] According to the following account published in a widely distributed 1958 history of Air Force balloon operations, _Contributions of Balloon Operations to Research and Development at the Air Force Missile Development Center Holloman Air Force Base, N. Mex. 1947–1958_, a suspected Holloman balloon was tracked both visually and by radar over London, England on November 3, 1953. “English accounts of the incident contained such statements as ‘tremendous speed,’ ‘practically motionless,’ ‘circular or spherical and white in color,’ ‘emitting or reflecting a fierce light.’ Altitude was reported as 61,000 feet—and as no research balloon had recently been sent up from Britain, there was ample room for local saucer enthusiasts to claim the ‘unidentified flying object’ as proof of their theories. A much likelier explanation, however, is that this was really the balloon launched from Holloman on 27 October.”[79]