State Sen. Will Brownsberger (2nd Suffolk and Middlesex) reports Logan Airport is resuming a noise-abatement takeoff system the FAA ordered it to stop last summer.
Basically, late at night, weather permitting, the airport tries do all of its landings and departures over the water. That means planes are flying in opposite directions onto adjacent runways. The traffic has to be timed to separate them adequately and maintain safety. This is feasible only late at night when traffic is low.