Circling Approach — Page 201, Lesson 279

Let's start circling approaches. This is a brand-new topic, so I'll build it up from the ground. First, the name. The official term is Visual Manoeuvring (Circling), abbreviated VM(C). That's the phrase you'll see on charts and in regulations. It describes the visual phase of flight that happens after you've completed an instrument approach, and its whole purpose is to bring the aircraft into position for landing on a runway that is not suitably located for a straight-in approach. So picture this: you've flown an instrument approach down to a runway, but the wind or the runway layout means you can't just land straight ahead. You need to circle around visually to land on a different runway. That circling is VM(C). Now, a key point about what kind of approach this counts as. Any instrument procedure — whether it's a precision approach or a non-precision approach — may be used to get you to the point where you start circling. But here's the catch: the descent in the final segment will be to the MDA/H for VM(C), as defined and calculated in section 8.38. And the procedure itself is defined as non-precision only, regardless of the type of approach you flew. So even if you flew a precision approach, once you're circling, it's treated as a non-precision procedure. That's an important distinction. Let me unpack MDA/H for you. That stands for Minimum Descent Altitude or Minimum Descent Height. It's the lowest altitude or height you're allowed to descend to without having the required visual reference. In a non-precision approach, you descend to MDA/H, and you cannot go below it unless you have the runway environment in sight and are in a position to land. For circling, that's your floor. Next, section 9.2: Visual Flight Manoeuvre. A circling approach is a visual flight manoeuvre, which means you must keep the runway in sight at all times. And here's the reality: every circling situation is different. The variables include the runway layout, the final approach track, the wind, and the meteorological conditions. Because of all these variables, there can be no single procedure that will cater for every situation. So you can't just memorise one standard circling pattern — you have to adapt each time. After you make initial visual contact, the basic assumption is that the runway environment — that's the runway markings, the lights, the approach lighting, and so on — will be kept in sight while you're at MDA/H for circling. So the moment you lose sight of that runway environment, you have a problem, and we'll get to that in a moment. Now, section 9.3: The Visual Manoeuvring (Circling) Area. VM(C) is only permitted inside a defined area called the VM(C) area. This area is determined for each category of aircraft by drawing arcs related to the aircraft's manoeuvring speed, centred on each runway threshold, and then joining those arcs with tangential lines. So you draw arcs around each threshold, and you connect them with straight lines that just touch the arcs — those are the tangents. That gives you the boundary of where you're allowed to circle. The radius of those arcs is related to four things. First, the aircraft category — aircraft are categorised by their speed. Second, the speed for each category. Third, the wind speed, which is assumed to be 25 knots throughout the turn. And fourth, the bank angle, which is taken as 20 degrees or rate 1, whichever requires less bank. Rate 1 means a standard rate turn, which is 3 degrees per second. So the bank angle used for the calculation is the smaller of 20 degrees or rate 1. Let me show you what this looks like. That's Figure 9.1. You can see the Visual Manoeuvring (Circling) Area drawn around the runway, with the radius R marked. And R is based on aircraft category and speed, as I just described. Now, section 9.4: Prohibited Sector. The area may be sectored, meaning it's divided into sectors, and VM(C) may be precluded from a particular sector where an unrealistic MDA/H for VM(C) would otherwise exist. In other words, if circling in a certain sector would force the minimum descent altitude or height to be unreasonably high — because of obstacles, for example — then that sector is simply prohibited. In that case, the published information will specify the sector and the restriction. So you'll see it on the chart: "you cannot circle in this sector." Now, section 9.5: Missed Approach While Circling. This is critical. If you lose visual reference while circling to land from an instrument procedure, you must follow the missed approach specified for the instrument approach runway — not the runway you were trying to circle to land on, but the runway the instrument approach was designed for. So the missed approach procedure is tied to the instrument approach runway. Here's the expected sequence: the pilot will make a climbing turn towards the landing runway — that's the runway you were circling to land on — and when overhead the aerodrome, the pilot will establish the aircraft climbing on the specified missed approach track. So you climb, turn towards the runway you wanted, and once you're overhead the aerodrome, you get onto the published missed approach track and follow it out. Let me show you that. That's Figure 9.2, illustrating the missed approach while circling. Finally, section 9.6: OCA/H for Visual Manoeuvring (Circling). This is the table of values you need to know. OCA/H stands for Obstacle Clearance Altitude or Obstacle Clearance Height — the lowest altitude or height that ensures clearance from obstacles. The table shows the OCA/H for visual manoeuvring and the minimum visibility for the procedure. But beware — and this is a direct warning from the text — these are the ICAO data, and they are different from the JAR-OPS data, which is required learning for Operational Procedures. So don't mix them up. This table is ICAO. Let me read the table for you. Aircraft are categorised A through E. Category A: Obstacle Clearance is 90 metres (295 feet). The lowest OCH above aerodrome elevation is 120 metres (394 feet). Minimum visibility is 1.9 kilometres (1.0 nautical mile). Category B: Obstacle Clearance is 90 metres (295 feet). Lowest OCH above aerodrome elevation is 150 metres (492 feet). Minimum visibility is 2.8 kilometres (1.5 nautical miles). Category C: Obstacle Clearance is 120 metres (394 feet). Lowest OCH above aerodrome elevation is 180 metres (591 feet). Minimum visibility is 3.7 kilometres (2.0 nautical miles). Category D: Obstacle Clearance is 120 metres (394 feet). Lowest OCH above aerodrome elevation is 210 metres (689 feet). Minimum visibility is 4.6 kilometres (2.5 nautical miles). Category E: Obstacle Clearance is 150 metres (492 feet). Lowest OCH above aerodrome elevation is 240 metres (787 feet). Minimum visibility is 6.5 kilometres (3.5 nautical miles). So you can see the pattern: as the aircraft category gets bigger and faster, the obstacle clearance, the OCH, and the minimum visibility all increase. Category A is the smallest and slowest, Category E is the largest and fastest. Let me show you that table. That's Figure 9.3, the OCA/H for visual manoeuvring (Circling). So to tie it all together: you fly an instrument approach, you descend to MDA/H, you keep the runway environment in sight, you circle within the VM(C) area at or above OCA/H, and if you lose sight, you execute the missed approach for the instrument approach runway. That's the complete circling picture.