Capital Airlines Flight 300, a Douglas DC-6 operating a scheduled flight from Washington, D.C. to Columbus, Ohio, engaged in a mid-air collision with a United States Air Force Lockheed T-33 jet trainer. The accident took place as the Capital Airlines flight was on its landing approach near Brunswick, Maryland. The T-33, which was conducting a routine training exercise, entered the airspace occupied by the commercial flight, leading to the catastrophic collision. Both aircraft were severely damaged, resulting in the loss of all 52 passengers and crew aboard the DC-6 and 3 individuals from the T-33 crew.

The aftermath of the incident prompted immediate investigations by both civil and military aviation authorities. Eyewitnesses reported seeing the aircraft in a steep dive before they collided and crashed into the ground. The National Transportation Safety Board (NTSB) undertook a thorough investigation to determine the causes of the accident, which revealed deficiencies in communication and coordination between air traffic control and military operations. After the crash, the aviation community emphasized the need for improved regulations and procedures for ensuring the safety of commercial flights within proximity to military training operations.

In response to the findings, new safety measures and protocols were implemented to mitigate future risks associated with the coexistence of commercial and military aviation. Notifications for military exercises and better delineation of airspace were established to prevent such tragedies from occurring in the future. The event served as a significant case study in air traffic safety and management, highlighting the importance of stringent operational practices in aviation.