With the 20th stopgap funding extension for the nation’s aviation system about to expire, the congressional stalemate over a multibillion-dollar, long-term funding bill has turned into a strikingly nasty squabble.

If it isn’t resolved this week, the Federal Aviation Administration may face a partial shutdown on Friday. Air traffic controllers would remain on the job, but the FAA would not be able to collect ticket tax revenue that support the system and nonessential employees might face furloughs.

“Summer is the busiest travel time of the year,” said former FAA administrator Marion C. Blakey, now president of the Aerospace Industries Association. “No one wants to see the FAA turned upside down, especially now.”

This week, House Democrats bypassed Transportation Committee Chairman John L. Mica (R-Fla.) with a direct appeal to Speaker John A. Boehner (R-Ohio), urging him to schedule a conference committee meeting to resolve differences in long-term bills passed by the two bodies.

Mica has delegated staff members to work with the Senate to reach agreement, contending that “the current Senate leadership . . . refuse to negotiate in the best interest of the American public.”

From the Senate side, Commerce Committee Chairman John D. Rockefeller IV (D-W.Va.) fired back that “the House has demonstrated that it is not serious about getting a comprehensive bill done.”

The divide at the forefront of the argument is money: The House has approved a four-year plan that would cost $60.1 billion; the Senate passed a two-year bill at $34.5 billion.

But the real sticking points, staff members in both bodies say, are a trio of minor issues that matter more to some members of Congress than they do to the majority of the traveling public or the general aerospace industry.

Funding at 2007 levels?

The gallows humor making the rounds in the aviation community — with the 21st extension looming, stop-gap funding now will be old enough to drink — masks a real fear that the uncertainty of continuing to fund aviation at 2007 levels will stall airport expansionsand slow progress on a $40 billion air traffic system expected to revolutionize air travel.

“To the general public, there has been little apparent impact of this short-term funding arrangement, because the FAA continues to perform its core functions,” said Bobby Sturgell, former acting administrator at the FAA and now a vice president at aviation supplier Rockwell Collins. “However, the lack of long-term funding causes real damage to airport improvement projects, capital programs and certification of industry products, which provide jobs and promote economic activity. ”

Even another extension, usually a formality when Congress fails to advance funding packages, was thrown into doubt this week when Mica inserted controversial provisions in the House extension bill.

The White House on Wednesday denounced that bill because it “includes controversial provisions that, because they have not been negotiated, needlessly threaten critical FAA programs and jeopardize thousands of public and private sector jobs.”

The FAA said a failure to extend its funding would lead to the furlough of about 4,000 workers beginning Saturday.

The three disagreements that have stalled compromise on the long-term spending bills are over federal subsidies for flights to rural airports, the number of flights that should be allowed at Washington’s Reagan National Airport and anti-union restrictions in the House bill.

Making it personal

The Essential Air Service program, which spends about $163 million a year to subsidize flights to 109 small towns, was created in 1978 when airline deregulation raised fears that commercial service to rural areas could end.

Mica targeted it in the House spending proposal, and he has included a provision in the FAA extension bill this week that would eliminate EAS subsidies to 13 airports that are within 90 miles of a larger airport.

Three of those airports are in home states of Senate leaders Rockefeller, Harry M. Reid (D-Nev.) and Max Baucus (D-Mont.).

The House bill also seeks to undo a ruling by the National Mediation Board that would make it easier for airline and railway workers to unionize.

Senate Democrats have insisted that repeal of the mediation board rule be removed from any final bill.

Rockefeller accused Mica of including the rural airport provision in the extension bill in retaliation for the Senate’s refusal to accept the labor provision.

“Your attempt to punish the Senate by hurting small-community air service has backfired. This language only guarantees that the Senate will reject the FAA extension,” Rockefeller said in a letter sent to Mica on Tuesday.

Mica didn’t deny that, saying it was a message to the Senate that “we want this finally resolved.”

The number of flights that should be allowed at National has long been a source of friction between members of Congress from the Washington region, who are concerned about noise and the region’s two other major airports, and their colleagues from distant states, who want more direct flights home.

The Senate bill says five new round-trip flights can be added at National and the routes for seven existing flights can be extended to the far reaches of the country. The House bill contains new slots, too, but with different requirements and restrictions.

“At this point, it looks like National could be resolved,” a House staff member said. “It’s the labor provisions and, to a somewhat lesser extent, EAS that are the big hang-ups.”