Alex Thomas knows what’s coming.

He’s seen it before outside the window in the Operations Department above Pittsburgh International Airport’s Airside Terminal.

“I’ve seen it happen within minutes,” said Thomas, duty manager for the Allegheny County Airport Authority. “Especially on hot, humid afternoons, you’ll see the sky get black very quickly and the next thing you know a thunderstorm is right there on your doorstep.”

Thunderstorms, especially those that develop quickly as regular summertime occurrences in western Pennsylvania, present major challenges for the entire airport – especially for ground operations. It falls on Thomas and his co-workers to alert all colleagues working on the airfield that lightning is in the airport’s vicinity.

And with warmer weather approaching, thunderstorm season means everyone needs to be aware.

Using a three-stage system, airport operations notifies the airlines, ground handlers and others when lightning is within 17 miles, when it moves to within five miles, and when lightning has cleared the area.

At 17 miles out, Thomas said, “we’ll communicate over radio and our emergency text system that we are in Lightning Condition Yellow, which advises all ground workers to use caution.” The airside terminal also has flashing beacons outside to indicate the current lightning condition.

According to Thomas, yellow is an awareness alert that severe weather is most likely imminent but that all ground activities may continue. When the lightning is within five miles, the airport moves to Lightning Condition Red. Fueling is prohibited and all airport employees are required to seek shelter in their vehicles or in the nearest building. This can result in delays for passengers.

The entire airport community has voluntarily committed to this program and actively participates in the lightning safety program.

“It’s a big airfield with lots of tall, metallic objects,” Thomas said. “During a storm, you’ll see lightning from where we sit.”

Under Condition Red, any tugs working their way from the jetway to baggage claim must wait for the storm to blow over and lightning stops. Only then will Operations declare Lightning Condition Clear, allowing ground operations – including unloading baggage – to resume.

“We understand the inconvenience for passengers,” said Patrick Carreno, vice president of Airport Operations. “But safety of our customers and employees is our top priority. It’s just too big a risk to send someone into harm’s way for baggage.”