What combination of wheels-up landing is the most dangerous and difficult to control?

The situation involving a single maingear being up during a wheels-up landing presents unique challenges that make it particularly dangerous and difficult to control. When one maingear is retracted while the other remains extended, the aircraft can experience significant asymmetrical forces during landing. This can lead to an uneven distribution of weight and thrust, resulting in a tendency for the aircraft to roll or yaw towards the side with the missing gear.

This condition complicates pilot control and increases the risk of veering off the intended landing path. Furthermore, the aircraft is likely to sustain severe structural damage on the side with the retracted gear, potentially leading to a loss of control. The combination of these factors makes a single maingear up landing notably hazardous compared to scenarios like all gears being up, where the aircraft would exhibit a more uniform behavior on landing.

In the case of double maingear up or one gear up, while there are still challenges, the imbalances and risks associated with a single maingear up landing make it the most dangerous configuration to manage during an emergency landing situation.