Under what conditions are takeoffs and landings prohibited according to Tradewind's Contaminated Runway Policy?

Takeoffs and landings are prohibited under Tradewind's Contaminated Runway Policy when braking action is nil, as this condition indicates that the runway surface is extremely compromised, significantly increasing the risk of an accident during these critical phases of flight. Additionally, the presence of more than 2 inches of dry snow also poses a significant hazard, as it can lead to reduced traction and difficulty in controlling the aircraft during takeoff and landing.

Both of these conditions, having nil braking action and more than 2 inches of dry snow, are established thresholds that reflect safety concerns for operational procedures. Therefore, the correct response encompasses both of these vital safety considerations.