Which type of aircraft cannot land when the ground slope exceeds 7 degrees?

The answer lies in the specific capabilities and limitations of aircraft types in relation to landing on slopes. Aircraft with skids, such as many helicopters designed for off-field landings, are particularly sensitive to ground slope. They require stable, level surfaces to safely land and take off due to the way their landing gear is designed. A slope exceeding 7 degrees compromises their landing stability and can lead to risks including tipping or losing control during landing.

In contrast, fixed-wing aircraft and helicopters with wheels can typically manage slightly steeper slopes due to their landing gear design and operational capabilities. Moreover, while it is true that any aircraft may have limitations based on design and condition of the terrain, skidded aircraft are particularly highlighted due to their sensitivity to such terrain features.

Therefore, the safe operational parameters for aircraft with skids are specifically constrained by ground angles exceeding 7 degrees, making them the correct focus for this question.