Which of the following conditions is necessary for a FLEX takeoff to be approved?

In the context of a FLEX takeoff, it is crucial that the anti-skid system is operational. The purpose of this system is to prevent wheel lock-up during braking, particularly in conditions where traction could be compromised, such as wet or slippery runways. If the anti-skid is inoperative, it could increase the risk of skidding upon landing, making it unsafe to proceed with a FLEX takeoff, where maximum efficiency is sought while still maintaining safety.

By ensuring the anti-skid system is operative, pilots can have greater confidence in the braking capabilities of the aircraft, which is essential when taking off with reduced thrust. This condition aligns with safety protocols, ensuring that the aircraft can operate reliably under various conditions.

The other conditions mentioned, such as whether wings must be de-iced or the status of all systems, do not directly relate to the critical safety aspect that the operational status of the anti-skid system provides during a FLEX takeoff procedure.