How does the presence of a clearway affect the allowed take-off mass and V1 when using an unbalanced field?

The presence of a clearway in an unbalanced field can significantly influence both the allowed take-off mass and the V1 speed, which is the decision speed during the take-off phase.

When a clearway is available, it allows for an extended distance that the aircraft can use in the event of an engine failure after V1. This additional distance improves safety margins, as the aircraft can continue its take-off roll instead of needing to stop immediately, thus reducing the risk of runway overruns.

As a result, knowing that there's a clearway extends the performance criteria, allowing for a higher take-off mass. The aircraft can carry more weight because it has the additional space provided by the clearway to either gain more speed or continue in the event of an engine failure.

At the same time, V1 can be lower. A lower V1 indicates that the aircraft can reach that critical decision speed sooner, benefiting from the clearway, as this speed is set based on the required acceleration and safety margins considering the available clearway distance.

Therefore, this answer indicates that with the availability of a clearway on an unbalanced field, an aircraft can safely operate at a higher take-off mass while still maintaining a lower V1 due to the increased