True or False: Changing your TAS by +/- 5% or 10 Knots is a required report to ATC.

True or False: Changing your TAS by +/- 5% or 10 Knots is a required report to ATC.

• A. True
• B. False
• C. Only 5% change
• D. Only 10 knots change

Answer: (A)

Significant speed changes need to be communicated to ATC because they affect where you will be and when you will be there. True: changing your true airspeed by about five percent or by ten knots is considered a notable change and should be reported. TAS directly influences your ground speed and estimated times of arrival. If you experience a change that meets or exceeds those thresholds, ATC’s ability to sequence traffic, apply appropriate spacing, and issue timely vectors or altitudes can be impacted if you don’t tell them. Reporting keeps everyone informed and helps maintain safe and efficient flow along the route. For example, if your TAS shifts from 250 knots to 210 knots, that’s a significant drop (more than 10 knots and more than 5%), and you would report it so ATC can adjust expectations and spacing. Smaller changes that don’t cross the threshold are generally understood as acceptable without a formal report.

Significant speed changes need to be communicated to ATC because they affect where you will be and when you will be there. True: changing your true airspeed by about five percent or by ten knots is considered a notable change and should be reported.

TAS directly influences your ground speed and estimated times of arrival. If you experience a change that meets or exceeds those thresholds, ATC’s ability to sequence traffic, apply appropriate spacing, and issue timely vectors or altitudes can be impacted if you don’t tell them. Reporting keeps everyone informed and helps maintain safe and efficient flow along the route.

For example, if your TAS shifts from 250 knots to 210 knots, that’s a significant drop (more than 10 knots and more than 5%), and you would report it so ATC can adjust expectations and spacing. Smaller changes that don’t cross the threshold are generally understood as acceptable without a formal report.