>> chris shuemake: 12 to 15 minutes. >> scott shuemake: 12 to 15 minutes, yeah.this white substance. >> kroft: the captain eventually dropped the stairs at the back of the plane and passengers evacuated one by one and walked across the taxiway to the terminal, but not before receiving one last instruction from the cabin crew. >> shanyl shuemake: they said, "make sure you take your carry- ons." >> chris shuemake: so then they, yeah, they told us, come on, say, "take your carry-ons and exit the plane out the rear." >> kroft: allegiant has yet to tell passengers what they were breathing, but the airline confirmed to us that the fumes were from skydrol 4, a hazardous hydraulic fluid. in a brief statement the day of the incident, allegiant said only that "a mechanical issue arose that caused a visible haze to appear. passengers deplaned with any carry-on items" and "proceeded to the terminal, per normal procedures." >> scott shuemake: they can't have the image on the 6:00 news of a bunch of passengers jumping with their-- with their arms crossed on a yellow-- on a yel

. >> chris shuemake: the smoke started pouring in out of all the vents you know, started fig witsmoke. >> shanyl shuemake: all i kept thinking was, "thank god we're on the ground." >> kroft: for the past seven months, we have been scrutinizing "service difficulty reports" filed by allegiant with the f.a.a. they are official, self-reported records of problems experienced by their aircraft. what we found raised some disturbing questions about the