About 20 minutes after takeoff on Tuesday, Capt. Tammie Jo Shults was steering a Southwest Airlines plane toward cruising altitude, generally considered the safest part of a flight. But then the left engine exploded.

The blast hurled debris into the side of the plane. A passenger window shattered. The cabin depressurized. A woman was partly sucked outside the plane. Passengers panicked and flight attendants sprang into action.

In the cockpit, Captain Shults remained calm as she steadied the aircraft, Flight 1380. “Southwest 1380 has an engine fire,” Captain Shults radioed to air traffic controllers, not a hint of alarm in her voice. “Descending.”

[Read more about the midair emergency, in which an Albuquerque woman died.]

In an instant, Captain Shults found herself in a situation most pilots face only during training: having to land a plane after an engine goes out.