Final answer:
When you're on an IFR flight plan and your ETA changes by more than 3 minutes than you have to advise ATC
Step-by-step explanation:
When you are on an IFR (Instrument Flight Rules) flight plan, if your estimated time of arrival (ETA) changes by more than 3 minutes, you are required to advise ATC (Air Traffic Control).
The reason behind this requirement is to keep ATC informed about any significant changes in your ETA. By notifying ATC, they can adjust their traffic management and coordination accordingly, ensuring the safety and efficiency of air traffic.
For example, if you are running late and your ETA is delayed by more than 3 minutes, ATC can take measures to accommodate your arrival time, such as providing you with a new routing or coordinating with other aircraft in the airspace.
It is important to note that accurate and timely communication with ATC is crucial for the overall safety and effectiveness of the air traffic control system.
In summary, if your ETA on an IFR flight plan changes by more than 3 minutes, it is necessary to advise ATC.