Pittsburgh International Airport saw its first big snowfall of the season on January 16, when 9.1 inches of white stuff blanketed the airport.

Days before, knowing the storm was coming, airport crews started developing a playbook for clearing the airfield, keeping everyone safe and the airport open.

Snow removal at the airport is like ballet, with every move choreographed. When the snow started falling Sunday evening, a parade of 30 snow removal vehicles began clearing the runways and taxiways. The airport coordinated with the FAA to determine what runways are needed during a snowstorm based off the winds.

A crew of around 70 people, including airfield maintenance, airport operations and mechanics worked around the clock to contain Sunday’s snowstorm.

Depending on the snowstorm, it can take 20-30 minutes for crews to clear a runway. Here’s a behind the scenes look of what the airfield looked like when the snow was falling and how the crews kept it clear.