A study sanctioned by the Federal Aviation Administration (FAA) predicts various harmful impacts to global positioning system (GPS) operations from the LightSquared network. The paper also asserts that risks to high precision GPS receivers remain even if LightSquared launches operations in the lower portion of the L-band in accordance with the company’s recently-revised proposal. Issued on July 12, the paper reports the results of tests performed by federal advisory concern RTCA, Inc. and the National Space-Based Positioning, Navigation, and Timing Systems Engineering Forum, and assumes that LightSquared will commence operations in 2014 in the upper 10 MHz portion of the L-band that is closest to GPS operations in spite of LightSquared’s pledge last month that it would refrain from using that spectrum until it receives FCC consent. With respect to LightSquared’s revised plan to commence operations in the lower 10 MHz portion of the band, however, the FAA observes that, “based upon existing data, LightSquared’s operation . . . would preclude the following critical capabilities that rely upon high-precision GPS receivers: airfield and flight procedure surveys, flight test tracking, space weather monitoring and GPS timing for computing resources.” The report further states that the company’s proposal to mitigate interference through in-line filtering is “assessed as high risk and not feasible” but admits that further study is needed to conclusively determine whether LightSquared’s proposed operations in the lower L-band “are compatible with civil aircraft receivers.” Asserting that the paper “conflates the upper 10 MHz with the lower 10 MHz and indicates LightSquared will commence operations in the upper band in 2014 when it has not said that,” a LightSquared Spokesman said, “we look forward to discussing this with the FAA.”