A stoppage time header from substitute Mark Roberts ruined St. Mirren's 100 per cent home record, but the visitors thoroughly deserved their point after a battling second half display.
It was just reward for Airdrie, who were served well by the industrious Marvyn Wilson in midfield and the dangerous Roberts after he replaced veteran Owen Coyle.
Saints dominated the first half but all they had to show for their efforts was an own goal in the seventeenth minute. Mixu Paatelainen released Brian McGinty down the left flank and the striker's cross-shot eluded Mark McGeown but Neil McGowan, in trying to avert a goal, took an awkward touch and the ball crossed the line before the full-back booted clear.
John O'Neill saw a drive go narrowly over the bar before Paatelainen headed wide after clever work by McGinty and David van Zanten. McGeown came to the rescue for besieged United, blocking bravely at O'Neill's feet. Saints ended the session with a Simon Lappin free-kick, easily held by McGeown.
After the break, United pressurised the home defence constantly. Willie McLaren stabbed a shot just wide and Roberts fired in a fierce drive which brought out a fabulous save from Craig Hinchcliffe low to his left.
Stephen Docherty came close with a rising shot, but the visiting fans erupted jubilantly when, in the second minute of stoppage time, the previously ineffectual Kevin Barkey crossed for Roberts to power his header past the flailing Hinchcliffe.