Broadband wholesaler LightSquared is objecting to a government report stating that its modified L-band network is not compatible with "several GPS-dependent safety-of-flight" systems.

The report, issued 13 January by the National Space-Based Positioning, Navigation and Timing (PNT) executive committee (EXCOM), stated that there are "no practical solutions" for rolling out the LightSquared network, even in the downgraded version proposed in June 2011 after an initial round of tests earlier showed incompatibility with GPS.

The unanimous position of the nine federal departments and agencies making up the EXCOM, including the military and Transportation Department, followed a batch of recent tests of general purpose GPS devices, some of which were non-certified aviation units, by the US Air Force.

Input also came from the FAA, which has been analysing with LightSquared officials the potential interference to certified aviation receivers, some used for navigation and safety functions like terrain awareness and warning systems (TAWS). The FAA has not stated publicly the results of those analyses, except for the portion of the EXCOM letter stating incompatibility with "several" GPS-dependent safety-of-flight systems, presumably including TAWS.

LightSquared, in a 13 January letter of protest to the US Federal Communications Commission, the agency that gave preliminary approval to its plan pending a non-interference nod from government and industry, said it has worked "diligently" with FAA engineers over the past year to "fully address all requirements defined by the FAA".

"The FAA has recently introduced new elements that had not been presented previously," said LightSquared in the 13 January letter. "Strangely, even though the FAA has not actually defined all of these requirements, it unilaterally decided to suspend any further collaboration, which deprives LightSquared of the opportunity to fully address their pending issues."

The company said it had "repeatedly told FAA that it will accept all of the technical parameters it has presented for protection of safety-of-life systems" but that the FAA has not responded.

"LightSquared believes the FAA has an obligation to resume participation in the good faith efforts that were productive at the beginning of this process in order to ensure that the LightSquared/GPS compatibility issues can be resolved to the satisfaction of the parties involved," the company stated.

LightSquared is asking the FCC to begin another round of testing, done independently of GPS manufacturers and the military, groups the company says have a considerable stake in a negative outcome.

The FAA would not comment further on the issue, other than to reiterate what was stated in the EXCOM findings.

Source: Air Transport Intelligence news