Smoke plumes rise over the area where a UPS cargo plane crashed at Louisville Muhammad Ali International Airport on Tuesday. Jon Cherry/AP
As highlighted by CNN
In Louisville, a UPS cargo plane – a 34-year-old jet – crashed. Although such an age may seem outdated for most passenger models, in the world of freight aviation such a service life is not uncommon.
There are no signs yet that the aircraft’s age contributed to the crash; the investigation is ongoing and will take time.
This accident serves as a reminder that cargo aircraft can have a substantial service life well beyond conventional limits. They usually retire primarily due to fuel-efficiency considerations rather than wear, and their actual flight activity is typically lower than in passenger models – about 30% less.
This is especially noticeable for the MD-11, which has a third engine mounted in the tail, unlike most twin-engine aircraft. In past decades, a tri-engine configuration was considered a hallmark of long-range capability and reliability, since with one engine out the aircraft was deemed safer over the ocean.
However, with the increasing reliability of twin-engine aircraft, this advantage has become less relevant. The MD-11 with three engines gradually fell out of favor as a passenger aircraft but continued operations as a cargo aircraft. Before the crash, UPS announced plans to gradually retire the MD-11 in favor of more fuel-efficient and modern cargo aircraft. According to Cirium, UPS has 25 MD-11s in operation and six in storage, FedEx – 38 in operation and 34 in storage, Western Global Airlines – four in operation and 12 in storage. Although the MD-11s still fly as cargo aircraft, the last passenger flight of this model occurred more than ten years ago – in October 2014 on the KLM route between Montreal and Amsterdam.
McDonnell Douglas produced only 200 such aircraft; the last orders for the MD-11 came in 1998 from FedEx and Lufthansa Cargo. By then the company had already merged with Boeing. Most passenger MD-11 variants were quickly converted to cargo. The aircraft involved in the crash had initially been delivered to Thai Airways in 1991, and in 2006 it moved to UPS and converted to cargo. Since then it has effectively become a refurbished aircraft, having undergone a full overhaul. The aircraft are also subject to conversion to passenger use – during D-check inspections, inspection and upgrades are carried out down to the bare airframe.
“An aircraft’s age is primarily determined by its most recent D-check”
Impact of the MD-11’s age on operators’ decisions
The economic side of operating older cargo aircraft often raises questions about replacing them with more fuel-efficient models. While the MD-11 is still in service, many companies are moving to modern aircraft with better fuel economy. The MD-11’s history shows how technological solutions of bygone years are gradually adapted or displaced from fleets.
Before the accident, UPS was also negotiating fleet changes – focusing on greater fuel efficiency and lower operating costs. According to Cirium, in recent years the MD-11 fleet numbers vary by operator: UPS has 25 aircraft in operation and 6 in storage, FedEx – 38 in operation and 34 in storage, Western Global Airlines – 4 in operation and 12 in storage. Although the MD-11s still fly as cargo, the last passenger flight of this model occurred in 2014.
The production history also provides context: MD-11s were produced in only 200 units, and the last orders for it came in 1998 from FedEx and Lufthansa Cargo; by then the company had already merged with Boeing. A large portion of the MD-11 passenger variants was converted to cargo. The aircraft involved in the crash had previously served Thai Airways from 1991, and in 2006 it became a cargo for UPS after conversion. Since then it has undergone a full update, and conversions often take place during regular airframe checks of the skin and structural joints.
Contemporary fuel requirements and maintenance continue to shape operators’ decisions regarding older models. At the same time, the MD-11 remains in the cargo fleet until it is fully replaced by more efficient solutions when economics and technology allow.
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