The UPS freighter that crashed in Louisville was a 34-year old jet. While that’s old for a passenger plane, that’s not so unusual in the world of air cargo.

UPS has been working towards sunsetting the MD-11F fleet it owns, which includes the last airframe of the type ever made, but it still flies 27 examples to this day. So, on the heels of a terrible crash that killed at least 12 people, the question is, why does UPS still rely on such antiquated cargo jets?

Airlines stopped flying MD-11s mainly because the aircraft initially failed to meet its promised performance, particularly in range and fuel efficiency, which led to many airlines canceling orders or replacing them with more efficient planes such as the Boeing 777 and Airbus A330, according to the Infinite Flight blog.

The MD-11 cargo jet flown by UPS that crashed Tuesday had been sidelined for six weeks before the deadly incident, according to federal investigators.

These 10 aircraft all range from 38 to 43 years of age, with the oldest Aircraft's range being recorded as 42.88 years old.

First conceived by the legendary Claude Dornier, the original Dornier 328 entered service in 1993. Even three decades later, approximately 150 of these aircraft remain in service globally. Today, under the leadership of Chief Engineer Thomas Ahn, himself ...

It's really hard to get a new fighter jet design off the ground. Given design challenges and costs it involves, it's amazing these ones have lasted so long.