What factor must be considered when responding to ATC speed commands?

When responding to Air Traffic Control (ATC) speed commands, regulatory limits are an essential factor to consider. Air traffic regulations set specific speed limits for different phases of flight, which must be adhered to for safety and efficiency in the airspace system. These limits can vary based on factors such as the type of airspace, altitude, and whether the aircraft is operating at or near its maximum performance parameters.

Understanding these regulatory frameworks ensures that pilots operate within legal safety margins, reducing the risk of incidents in busy airspace and ensuring compliance with air traffic directives. Additionally, adherence to these regulations is critical for maintaining safe separation between aircraft and effective traffic management in controlled airspace. Thus, recognizing the relevance of regulatory limits is key when responding to speed commands from ATC, as it encompasses both safety and legal considerations.