The FAA is pushing for early adoption of ADS-B by operators.
But Hickey warned, “operators will wait several years down the road to see what happens”. Speaking at the Air Traffic Control Association annual meeting recently in Washington, DC Hickey stated: “This is the most intractable problem I have been involved with in 31 years in aviation. Technology can solve this, but the real problem is time and cost.”
Hickey says the problem extends past US borders. “There are 2,000 aircraft that fly into the US daily and weekly. They will be significantly impacted if we can’t solve the GPS issue,” Hickey said.
LightSquared in January gained US FCC conditional approval to deploy an L-band (satellite-based) broadband network, pending the results of what turned out to be a massive four-month investigation of potential GPS interference by industry, government and LightSquared. The FCC’s January decision allowed LightSquared to roll out, pending the interference analysis, a full-time nationwide network based on an existing “ancillary terrestrial component” (ATC) provision that, in all other cases, allowed for rebroadcasting L-band signals only as gap-filler for land-based networks.
The final report in June showed that the LightSquared final deployment plan featuring an “upper” 10MHz channel near the GPS band operating simultaneously with a “lower” 10MHz band had a devastating effect for aviation’s certified receivers, precision receivers (including WAAS and certain ADS-B ground station components) and general purpose receivers (non-certified airborne units).
An internal FAA report, which Hickey said had been “inadvertently released” this summer, estimated a cost of $70 billion and loss of 800 lives if the network were to be deployed as planned.
Simultaneous with the June report however, LightSquared modified its operating plan, offering to use only the lower 10MHz channel and cutting ground transmitter power from an estimated 40,000 transmission towers. LightSquared has put plans for the upper 10MHz on hold, but has not relinquished the spectrum.
A new round of “targeted” testing on the lower 10MHz requested by the FCC in September is underway, set to be completed in November. In parallel, Hickey says the FAA has been meeting with LightSquared on a weekly basis since June to analyse the impact of a lower 10MHz deployment on certified aviation receivers, the only aviation GPS units required to conform to a minimum performance standard.
“We don’t always agree with them when we make assumptions on how to analyse [the interference],” said Hickey, adding, “It wouldn’t surprise me if the [final] report will be that we agree to disagree”.
Hickey said the FAA is making “an honest effort to find perhaps a win-win solution” that will allow both GPS and LightSquared operations, a nod to the White House’s initiative to expand broadband coverage in the US. He notes that analysis so far shows that precision timing and general use aviation GPS units “have to some degree a significant impact even on the lower [10MHz] band”.
LightSquared earlier this month announced that it had “solved” the interference issue for precision GPS units in the lower band using filters developed by several suppliers, some as cheap as $6, though company or independent testing has not yet confirmed how well the filters might work.
Even with a favourable outcome of the lower 10MHz testing with or without filters, there’s still concern in the industry about introducing the upper 10MHz channel at some point in the future. “The at-play business case is operations in the lower band,” said Hickey, “though I do think there is significant concern over the long term use of the upper band. LightSquared has not given that band back to the FCC.”
“If we have in any way a compromise to the [GPS] system, we compromise the future of NextGen”, Hickey said.
John Croft, Flight Global