Not even Brown could miss this one as a bunch of protesters from Plane Stupid took to the Parliamentary rooftops just as he arrived for Prime Minister's Questions on Wednesday.
As usual, Brown hit the wrong note, observing pompously that decisions in such matters (the third runway at Heathrow, due to be built by 2012 or shortly after) should be taken in the House of Commons, not on its roof.
But sometimes you have to go with the flow.
The trouble is that the decision has effectively been taken and not in the House either. It's been taken as the result of a ferocious lobbying campaign by the likes of BAA and British Airways on a febrile government that daren't say "No".
It also hasn't escaped attention that BAA's lobbying effort is being led by new signing Tom Kelly, who succeeded Alastair Campbell as Tony Blair's spinner-in-chief. Kelly was the one who accused his namesake scientist David Kelly of being "something of a Walter Mitty character" in the fall-out from the Iraq War (David Kelly subsequently committed suicide, of course).
This wasn't Tom Kelly's fault, neither is the third runway at Heathrow directly, which threatens to bring noise misery to Londoners all across the capital.
But the expansion of Heathrow is a disaster waiting to happen.
Yesterday morning,most of the media lined up fairly and squarely against it, with many of them dusting off the old plans for a Heathrow-plus airport somewhere in the Thames Estuary as a substitute.
This could be built, they say, for the cost of the London Olympics in 2012, which lasts for a whole two weeks.
We don't have room, or the knowledge of course, to debate here whether or not the "eastern option" is viable. I've been reading for years that the land surrounding the Thames Estuary is due to be underwater anytime soon, are they going to use seaplanes?
But this is a big nasty nettle that Brown needs to grasp, at least as far as embarking on real consultation that doesn't start out as a done deal.
Tory candidate for London Mayor Boris Johnson is due to announce his transport manifesto next week.
Up to now, we learn, air policy didn't play a large part in this in comparison to the Tube and the congestion charge, but I reckon it might do now.
It's also a fair bet that Tory leader David Cameron will be hissing furiously in Boris's ear between now and Tuesday.
If Brown lets the Tories run with this one he'll have just about everyone outside BAA and BA (including all the media) saying that Labour is a poodle of big business that cares nothing for earmuff-wearing voters in southern England (just the people he needs to vote Labour again if he's to stay in power).
Brown will huff and puff, saying that if he does what Plane Stupid wants him to do he'll look weak and Parliament will be festooned with protesters on every battlement.
But the government has already been shaken by the volume of protest about the third runway from more conventional protesters.
It's not difficult Gordon, change your mind and win some votes.