After the Airports Commission all but sunk Boris Island, the mayor sought to put the best possible gloss on the situation during his interview on the Today programme, declaring: "we're not dead yet, I think that's the good news."
Not dead yet, but certainly in the intensive care ward. In its interim report, the commission warned that Johnson's proposal of a new airport in the Thames Estuary would be "extremely expensive", would "present major environmental issues" and would have "uncertain" economic impacts.
The mayor contested these conclusions, insisting that his policy would not cost "anywhere near as much as he's [Howard Davies] saying" and that he could secure significant "international investment". He described the idea of a third runway at Heathrow as "completely crackers", warning that it would be "catastrophic for London and for quality of life" and would "consign millions of people to noise pollution".
But he conceded that Heathrow was the likeliest candidate for expansion, noting that while another runway at Gatwick would be "the least injurious" option, it would not deliver the "competitiveness boost" required since "the airlines will still want to go to Heathrow".
Asked how he would respond if the commission definitively rejected Boris Island next year (in a separate study) and if David Cameron pledged to support its final recommendation (due in summer 2015), he refused to accept that "hypothesis" but added that it would be a "grievous error" and "the wrong thing for the party". He ended: "I believe in going on and winning fights, rather than flouncing out" but, on this occasion, his struggle will almost certainly end in defeat.
After all parties rejected the option of a third runway after the 2010 general election, the policy has made a remarkable comeback. But since both David Cameron (who declared in 2009: "the third runway at Heathrow is not going ahead, no ifs, no buts") and Ed Miliband (who nearly resigned as energy secretary in the last government over the issue) have a mutual interest in avoiding the subject, expect all parties to maintain a conspiracy of silence throughout the campaign.