"I flew from Exeter to Aberdeen for a funeral. Is that frivolous?" Just one of the barbs that flew at one of the most fractious fringe events so far, a Greenpeace-sponsored event on airport expansion.
It was apparent from the opening exchanges between climate change campaigners and airline industry representatives that the statistical skirmish over aviation's contribution to global warming is far from over.
One fact is followed by a contradicting statistic, or just an accusation that the speaker is talking rubbish.
For instance, Richard Brown, the eloquent boss of Eurostar, said plane contrails were like "factory chimneys in the sky".
No, they're not, said Roger Wiltshire of the British Air Transport Association, because our industry is overflowing with people who know their science and we can explain these things better than anyone else. "Do not try to extrapolate and misuse scientific information that is out of date."
But one thing was clear from this meeting. The looming consultation over a third runway at Heathrow - expected at the end of next month - is going to be a major event.
Joss Garman, a member of the Plane Stupid group, and Greenpeace's chief scientist, Douglas Parr, both said that people would stage a protest of Twyford Down proportions if the government did not attempt to curb aviation growth - starting with that third runway.
The government is almost certain to sanction Heathrow expansion next month, which will elevate the aviation debate to a new pitch.
BATA and the chairman of pro-airline group Flying Matters, Brian Wilson, said aviation was being singled out unfairly and disproportionately by the green lobby.
Nonetheless, it was clear from today's packed meeting that the issue is totemic for environmentalists, and the industry faces a prolonged public relations battle where its opponent is passionate, eloquent and believes its grasp of science - let alone its moral conscience - is far more robust than theirs.
