FCC officials told Congress on Friday that the GPS industry should have raised concerns about interference long before it gave LightSquared the go-ahead for a wholesale wireless service in an adjacent band.

The Commission is in hot water over its handling of LightSquared after it fast-tracked the company’s plan to launch LTE in spectrum next to GPS bands, then stopped LightSquared from moving forward because of problems with GPS interference.

The military, GPS manufacturers, aviation industry and other sectors were in an uproar over LightSquared because its service had the potential to knock out a wide swath of mission-critical GPS receivers.

The FCC sought to deflect blame during testimony before the House Energy and Commerce Committee’s Oversight and Investigations Subcommittee on Friday. Neither LightSquared nor any FCC commissioners appeared at the hearing. Instead, the agency was represented by Mindel De La Torre, head of the international bureau, and Julius Knapp, head of the office of engineering and technology.

During the decade before it received LightSquared’s waiver request in November 2010, the GPS industry had “numerous opportunities” to bring up the issue but failed to do so, De La Torre and Knapp said in a joint statement.

“Despite participating in multiple proceedings, and raising other interference issues that were ultimately resolved to the GPS industry’s satisfaction, it did not do so,” they said. “The FCC would have investigated any complaints as soon as they were raised and attempted to mitigate at that stage.”

The officials also faulted “unfiltered or poorly filtered GPS legacy devices” that picked up signals from the neighboring frequency where LightSquared planned to launch its network. The issue was not LightSquared’s signal bleeding into the GPS band, “rather, it results from legacy GPS devices listening into the band next door to them. In effect, we discovered that some GPS legacy equipment effectively treats the GPS spectrum and the L-band spectrum as one band.”

The argument over receiver design is a favorite of LightSquared, which has long blamed manufacturers for making GPS devices that pick up transmissions from nearby spectrum. The GPS industry maintains that its receiver design was not problematic under the FCC’s former standards for LightSquared’s spectrum.

Jim Kirkland, general counsel for GPS company Trimble, called the FCC’s testimony “deeply misguided and wrong.” The FCC repeatedly promised that spectrum near GPS bands would only see limited use and that formal proceedings would take place before making any changes, he said.

The FCC repeatedly committed to these government users that it would proactively protect GPS, including explicit statements to that effect in 2003 and 2005, and government users and industry relied on these commitments. Now the FCC staff apparently believes that it was only obligated to consider GPS interference issues if GPS manufacturers raised them – which would be an astonishing abandonment of the FCC’s public interest responsibilities.

Kirkland also said the FCC’s explanation ignores its commitment to protect government GPS users and defended the GPS industry’s receiver designs.

The FCC’s statements about GPS equipment design “are all based on the assertion that the FCC put government and private industry on notice that ubiquitous terrestrial use of the mobile satellite band would be allowed. Since the FCC in fact said exactly the opposite up until 2010, GPS equipment was designed based upon the permitted, compatible use of the MSS band,” Kirkland said.

LightSquared has not released comment on the hearing. The company is currently in bankruptcy but insists it is still working to find a way to move forward with its LTE network. It invested about $4 billion in its LTE plans and signed contracts with dozens of potential customers before the FCC moved to stop it.