The lap times were calculated differently back then. He left the pits after session had started and crossed the timing line on the track when seven minutes and 16 seconds had gone in the session. And then most likely car broke on the next lap.
By the way, Mark Blundell set a time of 16 minutes and 42 seconds at 1995 Japanese GP qualifying in a similar way. Left the pits, drove outlap and then spun on his first flying lap. To make it worse he crashed heavily in Saturday free practice and was forced to sit Saturday qualifying. At that time, however, all drivers qualified for the race, so Blundell started the race 23rd (after Aguri Suzuki was injured and did not start) and last position, finishing 7th less than two seconds from Mika Salo in 6th place.
here's Blundell's FP crash:http://www.youtube.com/watch?v=ozIDRE3667k