What is the maximum runway slope permissible for takeoff and landing?

The maximum permissible runway slope for takeoff and landing is generally accepted to be plus or minus 2 degrees. This standard is critical for aircraft operations, as excessive runway slopes can significantly impact an aircraft's performance during takeoff and landing phases. A slope beyond this limit could lead to difficulties in controlling the aircraft, particularly for heavy or larger aircraft, as they require careful management of lift and drag.

Maintaining a slope within this range ensures that pilots can maintain adequate control and performance margins during these critical phases of flight, enhancing safety and operational effectiveness. The other options suggest steeper slopes, which could compromise aircraft handling, performance, and safety during critical airport operations.