Five minutes from the break Ross Campbell beat goalkeeper David Hutton from the penalty spot, then Terry Masson made it 2-0 midway through the second half. Leighton McIntosh’s injury-time strike came too late for Airdrie.
East Fife could yet catch Montrose, who are now five points ahead of them, but they lost 3-0 at Dumbarton, a result that ensures the home side’s League One status.
Dumbarton’s Craig Barr scoring first and Dom Thomas increasing their lead. Calum Gallagher put the result beyond doubt with the third midway through the second half.
Stranraer also guaranteed safety with a 3-0 victory over Brechin City. Mark Lamont netted after just nine minutes and Alistair McCann doubled their advantage three minutes later. Elliott got the third late on.
Brechin will battle it out with Stenhousemuir to avoid the automatic relegation slot after Stenhousemuir lost 3-0 at home to Forfar Athletic. Dale Hilson put them in front, Adam Eckersley and John Baird adding the other two.