Why UPS was still flying the 34-year

(CNN) — 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.

There are no initial indications that the age of the McDonnell Douglas MD-11 was in any way a factor in the fatal crash that killed at least nine people shortly after take off from Louisville, Kentucky Tuesday evening. The cause is still under investigation and will be for some time.

But the crash does highlight how planes, can have a much longer long lifespan than the average flyer realizes. That’s because older planes are often retired due to fuel economy, rather than wear-and-tear on the aircraft itself. If a plane isn’t flying as much, fuel economy isn’t as large a concern.

And cargo jets fly about 30% less than passe