Chicago’s Aviation Police were best known for beating up David Dao when he wouldn’t give up his seat on a United Express flight two years ago. Now they have a new achievement: losing the master keys to the airport’s security.

It looks like something you’d borrow from the counter of a gas station to get into the bathroom around back — a set of keys dangling from a bulky piece of wood.

But this key set doesn’t lead to a dingy toilet, leaky sink and condom machine. It provides almost total access to O’Hare Airport. These keys lock and unlock perimeter fences and other key entry points.

There are only a handful of these clusters of master keys. They’re kept by Chicago Department of Aviation security officers who patrol the grounds, a line of defense against terrorists and trespassers. So they’re supposed to be closely guarded

But one of the sets went missing in April and never was found, even with the FBI and Chicago Police Department called in, the Chicago Sun-Times has learned.

They keys provided access to:

• 100 perimeter gates
  
• 150 other gates
  
• an “unknown amount” of doors, elevators and washrooms

Chicago O’Hare

If you’re wondering what it takes to get fired from a job with Chicago’s aviation security, this is it — but only because the officer was new and still on probation since “the city’s union contracts typically protect city employees at O’Hare from serious disciplinary action even after alarming incidents like runway breaches.”

Naturally the city says this was no big deal, once they learned the keys went missing they added overtime to watch for really bad people trying to access vulnerable spots in the airport using a key.

They keys, “tethered to the bulky piece of wood in an effort to keep them from getting misplaced” were never found and had to be replaced — although it seems to me that important keys gone missing for even a few minutes should be enough to force replacement, since they could be copied and returned. Replacement “took about a month” because when Chicago government contracts for locksmith service it doesn’t happen quickly.

As we learned after the David Dao incident the airports 300 “security officers” call themselves officers but aren’t actually law enforcement officers. They just have very important keys and use excessive force.