25- to 29-year-olds make up the biggest age group among commercial airline pilots

The world's attention shifted to the French Alps this week after a German airliner carrying 144 passengers and six crew members crashed into the mountain range, killing everyone on board.

On Thursday, a French prosecutor revealed that Andreas Lubitz, the 28-year-old co-pilot, appeared to have been alone in the cockpit during the plane's descent. The prosecutor alleged he deliberately maneuvered the A320 into a crash.

Lubitz's young age may seem surprising. But it's actually not uncommon in the industry.

Lubitz is among the age group that is most commonly commercial pilots. Federal Aviation Administration data analyzed by the General Aviation Manufacturers Association shows people aged roughly between 25 and 29 years of age are the biggest category of commercially-licensed pilots. The data reflects ages as of December 31, 2013.

Also interesting news from the survey: there are more than 1,600 commercially licensed pilots aged about 80 years and older.