Now, different nations may set their own specific limits for when you must… — Page 227, Lesson 223

I want to walk you through a specific requirement that comes up when you're already flying — the obligation to tell ATC about changes to your flight plan speed and estimated time of arrival. Let's start with the core rule: ATC must be informed of changes which occur to the flight plan speed and ETA. So if your true airspeed changes, or your estimated time of arrival at a waypoint or destination shifts, you have a duty to notify air traffic control. Now, different nations may set their own specific limits for when you must report. But there is an international standard from PANS-RAC — that's the Procedures for Air Navigation Services — Rules of the Air and Air Traffic Services, published by ICAO as Doc 4444. PANS-RAC requires that you notify ATC of a change in TAS — true airspeed — of a certain percentage, and a change in ETA beyond a certain time threshold. The question here asks you to fill in the blanks: changes of _ in TAS and _ of ETA must be notified. Let's look at the four answer options: a. 3% and 5 minutes b. 5 kt and 30 minutes c. 5% and more than 2 minutes d. 3 kt and 3 minutes The correct answer is option c: 5% in TAS and more than 2 minutes in ETA. So if your true airspeed changes by 5% or more, you must tell ATC. And if your estimated time of arrival changes by more than 2 minutes, you must also notify them. Notice that the TAS change is expressed as a percentage, not a fixed knot value — that's because a 5% change is relative to your actual speed, so it scales appropriately whether you're flying a slow piston aircraft or a fast jet. And the ETA tolerance is "more than 2 minutes" — meaning if you're exactly 2 minutes late or early, you don't need to report, but once you cross that threshold, you do. There's also a note at the bottom: "N.B. Initial FL260 acceptable." That's a separate point — it means that if you file an initial cruising level of flight level 260, that is acceptable for this particular exercise context. Now, the excerpt then moves into the broader topic of the ATC flight plan itself. We have an extract from ICAO Doc 4444, PANS-RAC, dated 22 November 2007, which gives us the official requirements for the flight plan form. The flight plan form should be based on the model in Appendix 2 of that document. Operators and air traffic services units must use this form for completing flight plans. The form should be printed, and it must include English text in addition to the language of the state concerned. So if you're in France, for example, the form would have French and English side by side. There's also a note that a different form may be provided for repetitive flight plan listings — that's for airlines that fly the same route regularly and submit a standing plan. Operators and ATS units must comply with the instructions for completing the flight plan form given in Appendix 2. Those instructions may be printed on the inside cover of flight plan form pads or posted in briefing rooms for easy reference. Then we have an important requirement about Required Navigation Performance, or RNP. If an operator cannot satisfy a prescribed route or area RNP — meaning the aircraft cannot meet the navigation accuracy required for that airspace — then prior to departure, the operator must advise ATC of the RNP types the aircraft is certified to meet. So you tell them what your aircraft can actually do. Let me define RNP clearly: Required Navigation Performance is a statement of the navigation performance accuracy necessary for operation within a defined airspace. The RNP type is a containment value expressed as a distance in nautical miles from the intended position, within which flights would be for at least 95% of the total flying time. For example, RNP 4 represents a navigation accuracy of plus or minus 4 nautical miles on a 95% containment basis. So if you're flying in airspace that requires RNP 4, your aircraft must be able to stay within 4 NM of its intended track 95% of the time. Finally, the excerpt starts to introduce the submission of a flight plan prior to departure, but that section is cut off here. We'll pick that up when we continue.