Freighters are in focus after five people tragically died after an Amazon.com cargo plane, operated by 21 Air, overshot the runway at Miami International Airport on Sunday, striking vehicles as it crashed through a perimeter fence.

The plane was a Boeing 767 jet that was built in 1994 and converted into a freighter in 2015.

The 767 was Boeing's original twin-engine widebody aircraft, competing with the Airbus A300. The 767 entered service in the early 1980s, almost a decade after the A300. Airbus and Boeing have been locked in a battle of technological one-upmanship for decades, with each new jet incorporating new technology to drive operating costs down relative to earlier models.

The 787 Dreamliner essentially replaced the 767 jets, incorporating new engines and lightweight composite materials. (The Boeing 777 jet is larger than the 787 and 767 jets.)

Boeing has made more than 1,300 767 jets. It has made almost as many 787s since that plane entered service in 2011.

Boeing no longer makes 767 jets for commercial flight. Many are still in service, however, operated by Delta Air Lines, United Airlines, and others. Boeing still makes the freighter version of the 767, with 81 unfilled orders.

Transport companies can order freighters from producers, but that's not the only say jets go into cargo service. Many passenger jets are converted to freighters at the end of their life. There are roughly 25,000 Boeing-sized commercial jets carrying passengers around the globe. The global airfreight market is about one tenth that size, with the 767 representing roughly one-third of the total fleet. FedEx operates about 150 767 jets. UPS operates about 100. Amazon Air operates about 60, but Amazon's planes are operated by third parties such as 21 Air.

Any problem with the plane could ripple through the industry if significant capacity needs to be upgraded or repaired. It's far too early to speculate on any outcome of the Miami crash, though.

The National Transportation Safety Board is investigating the Miami incident involving the 32-year-old jet. Planes, like cars, are often looked at by regulators to ensure they are safe to operate. Plane owners are the ones responsible for maintenance, with manufacturers such as Boeing functioning as technical support and parts supplier. Boeing, in conjunction with regulators, will also make owners aware of any design or structural flaws and updated maintenance procedures.

Boeing stock was down 0.4% in premarket trading on Tuesday at $211.30. The market likely has more to do with the drop than the accident. S&P 500 and Dow Jones Industrial Average were down 0.2% and 0.7%, with benchmark international oil prices at nearly $100 per barrel amid ongoing conflict in the Middle East.

Coming into Tuesday's trading, Boeing was down 2% year to date and down 8% over the past 12 months. Rising oil prices have hit shares, which were north of $240 shortly before the U.S. bombed Iran in late February.

Jet fuel, derived from oil, is a big expense for airlines, and higher oil prices mean more expensive plane tickets, threatening demand. Still, pricier oil also drives demand for newer, more efficient jets.