Washington: A little-noticed but extraordinary event took place during the Paris Air Show and it had nothing to do with the show. The Senate Armed Services Committee came within a whisker of officially killing the F-35 program.

The June 21 vote in a closed committee session came on an amendment offered by Sen. John McCain of Arizona, the self-styled crusader against Pentagon cost-overruns and sharp critic of the F-35 in recent times.

The amendment basically said that if the JSF Lot 4 cost rose more than 10 percent over the target cost the Pentagon’s largest weapon system would, as happened with the V-22, would be placed on probation. If costs kept rising at the same rate for a year then the program would be canceled. That’s right — the Senate Armed Services Committee nearly voted to approve a measure that could result in the world’s largest program being canceled in 18 months should costs keep rising.

Just how significant was this vote? “The idea that the Senate came within one vote of almost killing the program is almost beyond belief,” a Capitol Hill source said. The problem continues to be that several professional staff members — and thus their bosses — share “the perception that the program does not have a lot of controls in place,” the source said, adding that several staffers feel strongly that Lockheed is getting “a lot of money” thrown at the F-35 program “but no one has actually solved the problems.” And the assertion that Ash Carter, head of Pentagon acquisition, made that the F-35 might cost too much but is the Pentagon’s only alternative — what the source called the “too big to fail” argument — angers the Hill aides “because it ties their hands.”

McCain’s comments after the vote would seem to substantiate that analysis.

“If this weapon system continues to have horrific cost overruns, as it has, then we’ve got to end it,” McCain was reported saying by my Aviation Week colleague Jen DeMascio. And even though the measure died in markup, McCain told her he will keep pressing for it when the bill makes it to the Senate floor.

Lockheed, not surprisingly, declined to say much about why the vote occurred or what it might portend. “This vote occurred in a markup session that was closed to the public and we have no insight as to what was specifically discussed and why the vote turned out the way it did,” said F-35 spokesman Michael Rein.

While it seems extremely unlikely the program might actually be killed — who can imagine Lockheed letting costs get that far out of control after being confronted with such language — McCain has shown over the years he is nothing if not persistent. And this measure clearly flows from his recent questioning of Carter during the SASC’s F-35 hearing about what alternatives there might be to the JSF. Of course, McCain’s House colleagues are unlikely to approve anything close to McCain’s measure.

Boeing, certainly, is watching all this with great hope. They have made clear that they stand ready to sell the F-18 to anyone who isn’t happy with the F-35. The India competition may not offer Boeing a great deal of substantiation in that regard, but they are unlikely to let that stop them pursuing such lucrative possibilities.