Gretna were left stunned as a double either side at half-time from the visitors saw them crash to their second defeat.
Stephen McKenna headed Airdrie in front in the 41st minute and Brian McPhee made it two just a minute after the break to send the travelling fans into raptures.
Midfielder Steve Tosh went close for Gretna in the eighth minute when he sent a 20-yard free-kick around the wall but keeper Stephen Robertson sprawled to turn it past the post.
Airdrie were unlucky not to go in front in the 16th minute when Gretna didn't deal with a McPhee cross and only a brilliant last-ditch Derek Townsley slide tackle prevented Xavier Barrau from shooting with the goal at his mercy.
Five minutes later they went close again when Graeme Holmes smashed a 25-yard drive against the Gretna crossbar.
David Graham should have scored for Gretna in the 30th minute when Neil MacFarlane's perfectly-weighted ball sent him clear but the striker's tame effort was saved by the advancing Robertson.
Airdre took a shock lead four minutes before the break when Barrau swung over a left-wing corner and McKenna flicked a near-post header that ended up in the back of the net through a crowd bodies.
Gretna were left reeling two minutes after half-time when the ball was lofted in to the box and McPhee headed over a stranded Alan Main with Martin Canning smashing the ball into his own net as he tried to clear.
They almost added a third in the 68th minute when Stephen McDougall crossed for Holmes whose powerful header was brilliantly turned away by the diving Main.
Gretna came close to restoring some pride when Graham played in sub Matthew Berkeley whose left-foot drive was parried behind by Robertson.