Night Choppers

What is up with the helicopters that circle our neighborhood every night? They do regular flybys over the apartment and they are LOUD. The past few nights they've gone by around 11:30pm but earlier this week they did an hour-long tour of duty starting at 3:30am. When I dragged my tired ass out of bed to call the police and complain--earplugs be damned, there was no way to sleep with that droning outside the window--I saw the chopper flying a tight circle over part of San Vicente Blvd. with its spotlight down. Were they chasing someone? Helping out a road crew? Filming something? What's the deal? Something tells me that the corner of San Vicente and Montana is not a high crime neighborhood.