With the deadline fast approaching for the US Congress to pass legislation reauthorizing the FAA, it appears increasingly likely that lawmakers will approve another short-term extension for the agency, according to a source familiar with the matter.

In theory, if Sen. John Thune (R-South Dakota)—the chairman of the Commerce, Science and Transportation Committee—can keep the bill clean of controversial amendments, it would still be possible for the Senate to  pass the bill quickly. The Senate and House would then have to reconcile their respective bills before the Sept. 30 deadline, but since differences between the two are relatively minor, this could also be a fast process, according to the source.

For weeks, the Senate has been wading through a host of amendments that could be added to the bill, a process that is believed to be close to concluding. Just last week, committee chairman Thune told reporters he hoped to avoid another short-term extension, saying “It’s not in anybody’s best interest” to put it off.

But with the Senate Republican leadership eager to confirm Supreme Court Justice nominee Brett Kavanaugh before mid-term elections in November, the chances are increasing that Congress will opt for another short-term extension. The agency has been operating on temporary extensions since its last reauthorization bill expired in September 2015.

The prospect of another failure by Congress to reauthorize FAA before deadline has rankled aviation groups, who say that lack of long-term legislation increases uncertainty and impedes their ability to plan for the future. Earlier in August, a coalition of 30 aviation groups penned a letter to the Senate Leadership to move expeditiously on the legislation, writing that long-term legislation would afford them the “certainty to continue to build, invest, hire, innovate and grow.”

Ben Goldstein, Ben.Goldstein@aviationweek.com