What effective runway length is required for a turbojet-powered airplane at the destination airport if forecasted conditions are wet or slippery?

When considering the effective runway length required for a turbojet-powered airplane under wet or slippery conditions, a key factor is the increase in stopping distance due to decreased friction between the tires and the runway. Wet or slippery surfaces significantly reduce the aircraft's braking efficiency, which means that a longer distance is necessary for the airplane to come to a complete stop safely.

In this context, using 115 percent of the dry runway length is a standard practice to account for the additional risks associated with wet conditions. This calculation ensures that there is an adequate safety margin, as the aircraft may require more runway than what is typically needed under dry conditions. The increase considers variables such as reduced braking performance and potential hydroplaning.

This approach is generally accepted in aviation safety protocols to mitigate any risks the crew may encounter when landing on compromised runway conditions, ensuring that both the aircraft and passengers are safeguarded.