During an engine start, what should the crew do if an amber START is indicated in the N1 gauge?

When an amber START indication appears in the N1 gauge during engine start, it signals a potential issue that requires immediate attention. This cautionary alert typically indicates that the engine is not starting normally and may be experiencing difficulties such as insufficient RPM or other anomalies that could lead to a failed start.

In response to this amber warning, the appropriate action is to abort the start procedure. This decision is crucial for ensuring safety, as continuing with the start could lead to engine damage, risks of a fire, or other hazardous situations if the engine fails to start properly. By aborting the start, the crew can assess the situation, check for any underlying issues, and take the necessary troubleshooting steps or notify maintenance for further assistance, ensuring the aircraft remains safe and operational.

The other options do not appropriately address the risk posed by the amber START indication, as continuing the start or attempting to increase throttle could exacerbate the problem. Notifying maintenance may be necessary, but it would be a subsequent step after aborting the start to mitigate immediate risks.