KF Aerospace, based in Canada, has secured the world’s first Supplemental Type Certificate (STC) for converting the Boeing 737-800 into a passenger-cargo combi aircraft, enabling airlines to operate mixed passenger and freight configurations on the same flight. This milestone certification allows for flexible conversions that retain passenger seating while adding cargo capacity in the rear, addressing growing demand for hybrid operations in the aviation sector. The achievement positions KF Aerospace as a pioneer in narrowbody combi solutions, with the first conversions already underway at their facility.
KF Aerospace’s Role in Aviation Conversions
KF Aerospace has built its reputation as a specialist in aircraft maintenance, repair, and overhaul, and its latest project extends that expertise into a new niche for the Boeing 737-800. The company has long handled heavy checks and structural work on Boeing narrowbodies, and its experience with full freighter conversions created the technical foundation for the combi program. By applying the same engineering discipline to a mixed-use layout, KF Aerospace is using its MRO background to move from routine maintenance into higher value modification work that can reshape how airlines deploy existing fleets.
The Canadian company operates large modification facilities that are equipped to manage the extensive structural changes required to integrate passengers and cargo in a single cabin without compromising safety. According to reporting on the, those facilities are set up for complex interior reconfigurations, structural reinforcements, and systems upgrades that must all align with strict regulatory standards. For airlines and lessors, KF Aerospace’s role as both designer and conversion shop reduces program risk, since the same organization that engineered the solution is responsible for executing it on the hangar floor.
Development of the 737-800 Combi Configuration
The new combi layout divides the Boeing 737-800 cabin into a forward passenger section and a rear cargo zone, using lockable bulkheads to keep the two areas securely separated. KF Aerospace’s design allows for up to 132 passenger seats in the front portion of the cabin, while the aft section is configured as a dedicated hold with a volume of 52 cubic meters. As described in detailed coverage of the project, this split-cabin arrangement is intended to let operators match capacity to markets where passenger numbers and freight demand vary from flight to flight, rather than committing an aircraft entirely to one role.
Engineering work focused on reinforcing the cabin floor in the cargo area and integrating fire detection and suppression systems that meet regulatory requirements for carrying freight in the main deck. In accounts of the conversion effort, KF Aerospace engineers emphasized that the modifications were designed to preserve the original performance envelope of the 737-800, so airlines can plan routes and fuel loads using familiar parameters. Collaboration with Boeing ensured that the combi configuration remains compatible with existing aircraft systems, and technical briefings on the project note that the conversion can be completed in about 12 weeks, limiting downtime for operators that need aircraft back in service quickly.
Achieving Certification Milestones
Transport Canada issued the world’s first STC for the 737-800 combi on October 10, 2023, formally validating KF Aerospace’s design after a lengthy review process. The certification campaign included extensive structural analysis, load simulations, and flight trials to demonstrate that the modified aircraft met all applicable airworthiness standards for both passenger and cargo operations. According to detailed coverage of, the program required more than 5,000 engineering hours, underscoring the complexity of integrating a cargo compartment into a cabin that still carries up to 132 passengers.
Regulators evaluated the design against Transport Canada rules while also aligning it with Federal Aviation Administration (FAA) and European Union Aviation Safety Agency (EASA) standards, so that the STC can support operators in multiple jurisdictions. Reporting on the certification notes that this marks a shift from the more common freighter-only conversions of the 737-800, since the combi layout must satisfy both passenger safety requirements and cargo compartment regulations in a single airframe. KF Aerospace has indicated that the approval opens the door for additional variants, including potential extended-range configurations, which would give airlines more flexibility to deploy the combi on longer sectors where cargo demand is strong but passenger loads are uneven.
Industry Impact and Airline Adoption
The 737-800 combi conversion arrives at a time when airlines are still recalibrating capacity after sharp swings in passenger demand and a sustained boom in air cargo. Analyses of the program suggest that carriers can retrofit existing 737-800 fleets to carry both passengers and freight, potentially increasing revenue by 20 to 30 percent on routes where mixed traffic justifies a dual-role aircraft. By turning part of the cabin into a 52 cubic meter cargo zone while retaining up to 132 seats, operators can avoid flying empty belly holds or underutilized freighters, which is particularly important on short-haul and regional networks.
Early interest has come from regional and niche carriers in North America and Europe that operate dense short-haul schedules and need more flexibility in how they allocate capacity. Coverage of the market response notes that these airlines often serve communities where passenger numbers fluctuate by season, while cargo volumes from e-commerce and express shipments remain relatively stable. For maintenance providers, the new STC changes the competitive landscape, since KF Aerospace now offers a turnkey passenger-cargo solution that rivals without a comparable certification cannot match, and industry reporting highlights that this first-mover advantage could translate into a steady pipeline of conversion work.
Future Outlook for Combi Conversions
KF Aerospace aims to deliver the first converted 737-800 combi to a customer by early 2024, with plans to scale production capacity to about 10 conversions per year at its facility in Windsor, Ontario. According to program overviews, the company is organizing its lines so that structural work, systems integration, and interior outfitting can proceed in parallel, which is intended to keep the 12 week turnaround time achievable even as volumes increase. For airlines, that projected throughput means the combi option can be integrated into fleet plans on a predictable schedule, rather than as a one off modification with uncertain timing.
Looking ahead, KF Aerospace has signaled that it wants to adapt the STC concept to newer Boeing 737 models such as the MAX series, although any such expansion will depend on further regulatory approvals. Reporting on the company’s strategy notes that extending the combi architecture to additional variants would give operators a broader toolkit for optimizing existing fleets, at a time when supply chain delays and long lead times for new aircraft deliveries are constraining growth plans. By enabling airlines to extract more utility from in service 737-800s and potentially future models, the combi conversion supports a more sustainable approach to fleet management that relies on targeted modifications rather than large scale fleet replacement.
