How does using a clearway affect the field-length-limited take-off mass?

Using a clearway increases the field-length-limited take-off mass. A clearway is a designated area beyond the runway, which can be utilized in the event of an engine failure during takeoff. This area allows for an extended distance over which an aircraft can safely continue its takeoff even if it experiences a malfunction.

The presence of a clearway effectively extends the usable runway length, which enhances the aircraft's performance capabilities. Specifically, this extension allows for a higher take-off mass because the aircraft requires a shorter distance to reach the necessary speed for safe takeoff. Therefore, in scenarios where a clearway is available, pilots can legally operate at a higher mass, thereby optimizing both payload capacity and fuel efficiency.

The increase in maximum take-off mass is crucial for airlines looking to maximize operational efficiency, making the clearway a significant factor in takeoff performance calculations.