UPS Airlines has made the difficult decision to ground its fleet of McDonnell Douglas MD-11 aircraft for thorough inspections and potential repairs, following a tragic accident. This action could extend through the critical peak delivery season, according to an internal memo released on Wednesday.

Bill Moore, the president of UPS Airlines, informed employees that the fleet is grounded indefinitely to comply with Federal Aviation Administration (FAA) guidelines. Originally thought to be a matter of weeks, the inspection and repair process is now expected to take several months.

The decision comes in the wake of a devastating crash on November 4 in Louisville, Kentucky. The accident, which involved a fiery MD-11 plane, tragically resulted in the deaths of 14 individuals and injured at least 23 others when the aircraft’s left engine separated during takeoff. In response, cargo carriers proactively grounded their MD-11 fleets, preceding an official FAA directive.

Moore’s memo highlighted that Boeing’s ongoing evaluations indicate the inspections and repairs will be more complex and time-consuming than initially anticipated. “The process will be more extensive than we first thought,” he noted.

In a statement, a UPS spokesperson reassured customers that the company has contingency plans in place to maintain deliveries during the peak season. The spokesperson emphasized that UPS is committed to taking the necessary time to ensure the safety of all its aircraft.

The 109 remaining MD-11 airliners, averaging more than 30 years old, are exclusively used to haul cargo for package delivery companies. MD-11s make up about 9% of the UPS airline fleet and 4% of the FedEx fleet.

Boeing, which took over as the manufacturer of MD-11s since merging with McDonnell Douglas in 1997, said in a statement that it is “working diligently to provide instructions and technical support to operators” so that they can meet the FAA’s requirements.

The FAA said Boeing will develop the procedures for inspections and any corrective actions, pending approval from the FAA.