On a stormy day more than 34,000 feet above Paris, Air France Flight 1205 prepared to make its descent. Flight attendants began checking seat backs and tray tables, and passengers groggily emerged from naps.

Then a voice from the cockpit came over the intercom, offering an update on the weather (cloudy and 54 degrees) and the remaining flight time (about 30 minutes).

“Thank you for choosing Air France,” said Daniel Harding, the flight’s first officer. “And remember: Rehearsal is at 6 p.m.”

The cabin erupted into whistles and cheers. Harding, 49, an Air France pilot, also happens to be one of the world’s top orchestral conductors. And on this December day, he was flying his ensemble, the esteemed Orchestra dell’Accademia Nazionale di Santa Cecilia, from its home base in Rome to Paris for the start of a European tour. (A few dozen unknowing members of the public were also aboard.)

Over the past few years, the British-born Harding has led dual, and often dueling, careers: conducting Mozart and Mahler symphonies one day, piloting commercial flights to Paris, Milan, Stockholm and Tunis the next. He relishes the exacting regimen of flying — checking fuel figures, analyzing weather patterns, tallying passengers and cargo. He is also energized by the risks he can take in music.