Jason Rabinowitz, a self-described aviation geek tweeted the flight's trajectory in real time, uploading images of the plane climbing out of San Juan between the outer band of Irma and the core of the storm.
"Amazing stuff," Rabinowitz said.
Delta officials said the airline operated its last scheduled flight to and from San Juan "armed with the latest forecast from the airline's meteorology team." Flight 431 arrived a minute after noon to nine miles of visibility and light rain, the airline said. Winds were well below operating limits for the 737-900ER to safely operate at around 28 mph, and gusts up to 36 mph. Flight 302 departed San Juan with 173 passengers on board, the airline said.
"Our meteorology team is the best in the business," said Erik Snell, vice president for Delta operations and customer center. "They took a hard look at the weather data and the track of the storm and worked with the flight crew and dispatcher to agree it was safe to operate the flight. And our flight and ground crews were incredible in their effort to turn the aircraft quickly and safely so the flight could depart well before the hurricane threat."