The number of unwanted passenger aircraft skyrocketed during the COVID-19 pandemic. Owing to the global downturn in travel, planes have been left to gather dust on the outskirts of airports across the world. Airlines were forced to place hundreds of planes in long-term storage with little hope of recovery. 

At the same time, the cargo market experienced an unprecedented boom. There was a sudden need to transport a lot of emergency supplies, and the belly cargo capacity of passenger flights disappeared.  As a result, demand grew and prices doubled. 

Together, these two issues paved the way for a slew of passenger-to-freighter (P2F) conversions. 

Turning an old, usually second-hand, airliner into a cargo plane is not unusual. Some freight carriers, such as UPS Airlines, had a fleet that consisted entirely of such airplanes during the history of the company. However, during the pandemic, the trend appeared to escalate and conducting P2F conversions became a necessity and a growing stream of revenue for MRO companies.

This became so commonplace that centers, which focused specifically on P2F conversions, began to appear left, right and center, responding to the growing demand. Subsequently, a large number of aircraft were converted. According to numerous forecasts, including one by the IATA, full travel recovery is still far away, meaning that companies that got rid of their older passenger jets are probably not going to regret it. 

Nevertheless, it begs the question: what happens if an airline decides to reverse the conversion? Is it possible to change a recently converted freighter back into a passenger plane?

Converting the classics

Let’s look at some examples. There are many cases, but most of them involve a set of particular circumstances, including the restoration of vintage airliners.

The trend of using retired airliners for cargo duty has unintended consequences. During some point in its history, an aircraft will become a much sought-after antique, especially after most existing airframes are shredded for scrap. So, there is a significant chance that the last surviving examples of a particular aircraft model will be in a freighter configuration. However, most people, particularly aviation enthusiasts, would prefer to see such aircraft restored to their glory days. So, in this instance, the process of restoration usually involves deconversion. 

This is the case with what is potentially the last flying Lockheed L-1649 Starliner, a variant of the classic Constellation from the 1950s. The aircraft no. N7316C, which is, as of late 2021, being restored by Lufthansa (LHAB) (LHA), was turned into a freighter in late 1960s. It was eventually abandoned in the 1980s and picked up for restoration and deconversion a few decades later. 

The last two Douglas DC-4s, operated by South African Airways (SAA), experienced a similar fate. Although never converted per se, they were predominantly used as freighters by various airlines and the military. In the 1990s, SAA purchased the two planes and began work on their restoration. Not only was a 1940s vintage SAA livery added, but the interior was restored to its original configuration as well.

In addition, many of Douglas DC-3s (an even earlier aircraft, used extensively in WWII) were born as military transports, C-47 Skytrains or Dakotas. Sold to various airlines upon retirement, they proved to be well-suited for carrying passengers in harsher rural areas in both Africa and South America. Here, they have enjoyed relative, and quite phenomenal, popularity to this day.

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Pre-planned conversion

Most of the examples listed above are the result of specific circumstances, where reconversion was a necessary process to restore an old aircraft. Reconverting a new airplane is an entirely different matter and a lot more difficult. However, there are still exceptions. 

There are many cases when an aircraft has been built with a quick and easy conversion in mind. The smaller the aircraft, the easier the task. 

Back in the 1980s and 1990s, Danish cargo airline Star Air operated a fleet of Fokker F-27 regional turboprops, which were designed to be transformed within half an hour to carry passengers, and proved to be quite successful. 

Similarly, it took approximately 30 minutes to convert the Boeing 727-100QC (quick change) between configurations. More than 100 were delivered and used by various airlines. The initial concept was to operate the same aircraft as an airliner by day and as a freighter by night, which would greatly increase profitability. In the early 2000s, Boeing tried to resurrect the same concept with 737-300s and 400s. But for various reasons, the plans never came to fruition.

In the late 1960s, the original plans for the Boeing 747B also included a convertible freighter variant, which never saw the light of the day. A few decades later, the concept was finally implemented by one of its competitors, the wide-body McDonnell Douglas MD-11CF (not to be confused with the -CF designation on older Douglas aircraft, which meant ‘Combi freighter’). Six MD-11 convertible freighters were built. However, switching from passenger to cargo configuration took up to 24 hours, and back to passenger configuration took up to 48 hours. As a result, all McDonnell Douglas MD-11CFs were operated as pure freighters by cargo airlines.

One of the most interesting cases of back-and-forth conversion was UPS’s attempt to conduct passenger flights in the mid-90s. The airline converted six of its 727-100QFs into makeshift versions of the 727-100QC, so that the aircraft could be employed as airliners on weekends when demand for cargo services was low. Lavatories and other amenities were permanent, but the seats could be loaded on pallets through the cargo door, completely transforming the fuselage. The aircraft operated in this manner for half-a-decade, before eventually being retired in the early 2000s. 

Reconversion proper

The occurrence of permanent P2F reconversion is rare. However, they still take place. 

For example, US charter airline USA Jet Airlines operates a McDonnell Douglas DC-9 (N195US) that was converted into a freighter in the 1990s, and then reconverted to carry VIP passengers in the early 2000s. Despite being more than 50 years old, the aircraft is still operational. At least one Austrian Airlines Boeing 767 experienced the same fate when it was converted to a freighter while on lease to Lauda Air in the mid-2000s. A few years later, it was retrofitted to carry passengers. 

During both examples, the aircraft were converted and deconverted with long-term use in mind. The work was carried out by MRO companies in specialized facilities. Examples of temporary conversion and deconversion are more commonplace. At the beginning of the COVID-19 crisis, airlines started to carry cargo via passenger aircraft, which sometimes involved removing seats to allow more room for freight. 

Reverting such a ‘conversion’ was easy, and many airlines went with it as soon as passenger demand returned. For example, Kazakhstan’s Air Astana announced the conversion of its Boeing 767s back to passenger aircraft in late August 2021.

In conclusion, it is possible to reconvert an aircraft that was once changed to a freighter. But, if we look beyond the aircraft that were easily convertible by design, such occurrences are rare. Nevertheless, we can still harbor hope that a recently converted aircraft can become an airliner once again. But only if it remains in good enough condition to be considered an antique.