Just before 3 p.m. on Easter Sunday in 1988, Engineering Prof. Perry Samson ran into his backyard, anxiously peering up at the sky.

Wind speeds were almost 70 mph and tornado sirens were blaring. A vortex had been spotted nearby and the building thunderstorm was about to drop a twister.

His fellow Ann Arborites were hiding in their basements, but Samson, an extreme-weather junkie, stood outside his home examining the clouds for signs of rotation.

He worried about the storm's direction: It was headed straight for the brass 'M' in the middle of the Diag.

The storm, which had formed in a mobile home park on the southeast side of the city, rambled haphazardly northeast, damaging several garages along Scio Church Road.

The twister petered out before reaching campus, weakly touching down once more north of M-14 before dying.

That time, the University escaped relatively unscathed: the storm tore shingles off the Art and Architecture Building, cut power on the Hill and wrested a few light fixtures from University Towers, but it harmed little else.

For University officials in the Department of Public Safety and several other emergency planning offices around campus, disasters like the 1988 tornado are a constant source of concern.

DPS maintains extensive emergency response plans mirroring that of a small city. They cover a breadth of disasters like flooding, terrorism and hazardous material spills.

These plans are updated every day as University departments identify new safety hazards and reevaluate old ones.

Some procedures - like how DPS officers would respond to an active gunman or a bomb threat - are top secret. Others are distributed widely - posted on DPS's website, printed on flip charts in buildings across campus and taught to ushers at football games. Like most policies at the University, disaster planning is decentralized but loosely collaborative. DPS leads some initiatives, while University Health Services lead others. Some areas of campus just require fire drills. Others, like Michigan Stadium, are more complicated.

110,000 people with nowhere to go

Anyone who regularly attends Michigan football games knows the cardinal rule of fandom: don't bring a big bag.

Since Sept. 11 game security at Michigan Stadium has increased dramatically. Spectators aren't allowed bags larger than a two-slice toaster and police are constantly on the lookout for suspicious packages.

In line with federal regulation, airspace over the Big House is no-fly zone from one hour before the game until an hour after. Any planes entering the 3,000-foot-high, 3-square-nautical-mile space above the bowl must have clearance from air traffic controllers. Each football Saturday, a fire engine parks near the gates and stays for the duration of the game - just in case.

"Do we need to plan for terrorism? Yes," DPS Spokeswoman Diane Brown said. "Is it highly likely it would happen? Who's to say?"

She stressed that other emergencies pose a much more likely danger to fans. The biggest problem is evacuation - getting 110,000 people to move quickly and orderly out of a bowl-shaped structure with limited exits is obviously tricky.

Trampling is a very real threat, especially if scared fans try to escape via the field. On the turf, there's only one way out: through the tunnel, which could easily become blocked. It's not hard to imagine panicked fans crushing others against the field's brick wall in the rush.

Once everyone is out of the stadium, the problem becomes relocation. In the event of inclement weather, fans would have almost no safe place to go. No buildings in the vicinity could hold as many as the stadium, and other big buildings such as Chrisler Arena would only create more danger.

"When you are trying to take shelter from a tornado, you don't want to be under a large expanse roof like in Chrisler," Brown said.

In the summer, DPS meets with the Athletic Department to plan and train for emergencies. They discuss how to reduce panic during emergencies and administer first aid. But they know they can't outsmart Mother Nature.

"If we encounter that situation, we'll try to do the best we can," Brown said. "A little bit of it is just the risk people take when they come to an event."

Safe haven at the 'U'

At the University Hospital, patients' lives depend on ventilators and intravenous drips. Something as simple as a power outage could kill hundreds.

"The big difference between the hospital and a business or another school is that we have people in our care who are fragile," said Peter Forster, director of the hospital emergency department. "That puts a burden on us as caregivers to protect those people.