Rules of the Air — Page 115, Lesson 183

We're starting a fresh topic now — the operational rules that govern a flight once it's actually airborne, under the Rules of the Air. I want to walk you through three specific provisions: what happens when weather deteriorates below VMC, how position reports are structured, and the beginning of termination of control. Let's start with weather deterioration below VMC. VMC stands for Visual Meteorological Conditions — the minimum visibility and cloud clearance that allow a pilot to fly by visual reference, seeing and avoiding other traffic. If a VFR flight — that's Visual Flight Rules — is unable to maintain VMC in accordance with its current flight plan clearance, the pilot has a defined set of options. First, the pilot may request an amended clearance that would allow the aircraft to continue in VMC, perhaps on another route, either to the destination, to an alternate aerodrome, or to leave the airspace in which ATC clearance is required. If that amended clearance cannot be obtained to continue operating in VMC, then the pilot must notify the ATCU — the Air Traffic Control Unit — of the action being taken. That action is either to leave the airspace concerned, or to land at the nearest suitable aerodrome. Second, if the flight is being operated in a control zone, the pilot should request special VFR clearance. Special VFR is a specific clearance that permits a VFR flight to operate within a control zone in weather conditions below normal VMC. Third, if the above measures are inappropriate, the pilot requests an IFR clearance — Instrument Flight Rules — to continue the flight. Now let's move to position reports, covered in paragraph 6.41. Unless advised to cease position reporting — and that usually happens when under radar control — a controlled flight is to make reports at specified positions as soon as possible after reaching the position. The report must contain several elements. The first is the aircraft RTF identification call sign. RTF stands for Radio Telephony — that's the radio call sign used to identify the aircraft on the frequency. Next is the position for the report — where the aircraft is. Then the time the aircraft was over the position; usually the minutes will suffice unless there is a possibility of confusion. After that, the level of the aircraft when passing the point — that's the altitude or flight level. Then the next en route reporting position, and the ETA — Estimated Time of Arrival — for the next specified point. Finally, according to ICAO, the name of the next ensuing point. There's an important note here. If SSR mode "C" has been verified as accurate — SSR is Secondary Surveillance Radar, and mode C provides automatic altitude reporting — then the altitude or flight level may be omitted from the position report. Also, if a speed has been assigned by ATC, that speed is to be included in the position report. Let me give you the example of a full ICAO position report from the text: "London Airways this is GABCD, Pole Hill at 35, FL170, Dean Cross at 46, Glasgow next." Let's break that down. "London Airways" is the ground station being called. "GABCD" is the aircraft's RTF call sign. "Pole Hill at 35" — that's the position, Pole Hill, and the time, 35 minutes past the hour. "FL170" is the level — Flight Level 170, which is 17,000 feet on the standard pressure setting. "Dean Cross at 46" — that's the next en route reporting position, Dean Cross, and the ETA, 46 minutes past the hour. And "Glasgow next" is the name of the next ensuing point. Finally, we come to paragraph 6.42, Termination of Control. The excerpt begins this provision: "A controlled flight is t..." — and that's where the text cuts off. So we've covered the beginning of that statement, and we'll continue with it when we move forward. Let me make sure you have the full picture of what we've covered. We have three operational rules: the procedure for weather deteriorating below VMC, with its three options — amended clearance, special VFR in a control zone, or IFR clearance; the structure of a position report with its seven elements and the two notes about SSR mode C and assigned speed; and the beginning of termination of control.