Reallocating government spectrum to the wireless industry could be a long and difficult task, a top official from the U.S. Air Force told a CTIA audience on Wednesday.

Robert Wheeler, who serves as the agency’s deputy CIO, said that while the Defense Department is “working hand in hand with the industry” to free up the 500 MHz of spectrum called for under the National Broadband Plan, it could be extremely difficult to move existing technology to new bands.

For example, it isn’t possible to change equipment on satellites in orbit, so switching them about will take about a decade, “and that isn’t fast enough for industry,” he said.

The Air Combat Training System in the 1755-1780 MHz band also illustrates the difficulty of moving government users to new bands. The system is critical to giving the military an edge during combat missions – Wheeler described it as “the ability for us to do ‘Top Gun’ on steroids” – and is used for more than 10,000 training flights each month.

The problem is that it’s “smack dab in the middle of that particular band, and moving that will take years,” Wheeler said.

“It could have a disastrous impact to our nation if we get this wrong,” he said.

Issues like these have prompted the Defense Department to promote spectrum sharing with commercial users as an alternative way to make more efficient use of its spectrum resources, a technique Wheeler discussed in his presentation.

However, that proposal is controversial, as the method is unproven and is not yet commercially viable.

A recent report from the President's Council of Advisors on Science and Technology advocating spectrum sharing instead of reallocation was met with criticism by many in the wireless industry. FCC commissioner Ajit Pai also panned the report, saying he had “serious concerns about the report’s apparent dismissal of clearing and reallocating federal spectrum for commercial use."

The Defense Department’s current goal is to develop a long-term strategy so it isn’t forced to repeatedly uproot itself from its spectrum assignments. Wheeler reported that there are currently five different groups working on ways to share or vacate various blocks of government-owned spectrum.

“We want to do one move, want it to make sense,” Wheeler said.