Rules of the Air — Page 104, Lesson 164

Let's start with the core of what you need to know for this section: the visual meteorological conditions, or VMC. To fly under VFR — visual flight rules — these VMC must actually exist. And VMC is defined by three things: altitude, which can be expressed as a Flight Level; flight visibility, which is the forward visibility from the flight deck of an aeroplane in flight; and distance from cloud, both horizontally and vertically, for the relevant class of airspace. Now, I want to be clear about what "class of airspace" means here, because it drives everything. Classes of airspace are discussed fully in Chapter 14, but basically they specify what rules are permitted and what type of control, if any, is applied by the Air Traffic Service. So the VMC numbers you're about to learn are not universal — they change depending on which class of airspace you're in. And I'll say it plainly: it is imperative that you know the VMC. Let's look at the numbers. For Classes F and G airspace, at and above FL100 — which is 10,000 feet — the flight visibility requirement is 8 km, with 1000 feet, or 300 metres, vertically from cloud, and 1500 metres horizontally from cloud. Below FL100, the flight visibility requirement drops to 5 km. But there's a footnote on that 5 km figure: the visibility may be reduced commensurate with aircraft speed. That's a real operational point — the faster you're going, the more visibility you need to see and avoid, so the reduction is tied to your speed. Now, for Classes A, B, C, D and E airspace, the criteria are slightly different. At and above 10,000 feet, or FL100, it's the same: 8 km flight visibility, 300 metres — 1000 feet — vertically from cloud, and 1500 metres horizontally from cloud. Below 10,000 feet, the flight visibility is reduced to 5 km. So you can see the pattern: the higher you go, the more visibility you need, and the more separation from cloud you need. Now let's go back to Classes F and G, because they have an extra layer below 3000 feet. Below 10,000 feet but above 3000 feet, the flight visibility is 5 km. But below 3000 feet AMSL — that's above mean sea level — and within 1000 feet of the surface, where the surface elevation is above 3000 feet, the flight visibility remains 5 km, but VMC would exist if the aircraft was clear of cloud and within sight of the surface. That's the condition abbreviated as CCISG — clear of cloud and in sight of the ground. So in that low band, you don't need the full cloud separation distances; you just need to be clear of cloud and able to see the ground. Now let's move to the human side of this — the pilot-in-command responsibilities. There are four definitions you need to know precisely. The Commander is a designated pilot amongst the flight crew who is qualified as pilot-in-command, and who may delegate the conduct of the flight to another qualified pilot. The Pilot-in-command, or PIC, is a pilot who is responsible for the operation and safety of the aeroplane during flight time. The Pilot Flying, or PF, is the pilot who, for the time being, is in charge of the controls of the aeroplane. And the Pilot not Flying, or PNF, is the pilot who is assisting the pilot flying in accordance with the multi-crew co-operation concept, when the required flight crew is more than one. Notice the distinction: the PIC has the legal responsibility for the whole operation and safety, while the PF is the one actually handling the controls at any given moment. In a multi-crew environment, the PNF supports the PF under the multi-crew co-operation concept. Finally, there's the pre-flight responsibility. Before beginning a flight, the pilot-in-command shall become familiar with all information appropriate to the intended operation. And for flights away from an aerodrome, and for all IFR flights — instrument flight rules — the pre-flight action shall include a careful study of available current weather reports and forecasts, taking into consideration fuel requirements. So the PIC isn't just responsible in the air — that responsibility starts on the ground, with a thorough study of the weather and fuel planning before you even start the engines.