All Weather Operations — Page 61, Lesson 98

I want to walk you through the take-off minima requirements for All Weather Operations. This is a critical part of your training because it defines the lowest visibility conditions in which you are legally allowed to start a take-off. Let's start with the first category of aeroplanes. We're talking about multi-engine aeroplanes whose performance is such that, if a critical power unit failure happens at any point during the take-off roll, the aeroplane can either stop safely on the remaining runway, or continue the take-off all the way up to a height of 1500 feet above the aerodrome while clearing any obstacles by the required margins. For these high-performance aeroplanes, the operator must establish take-off minima expressed as RVR/visibility values — that's Runway Visual Range or meteorological visibility — and those values cannot be lower than what's shown in Figure 5.2. Let me read you that table from Figure 5.2, because you need to know these numbers precisely. First, if the aerodrome has nil facilities — no runway lighting or markings at all — and it's day only, the minimum RVR/visibility is 500 metres. If the runway has runway edge lighting and/or centre line marking, the minimum drops to 250/300 metres. The note says the higher value applies to category D aeroplanes — those are the largest aircraft, like a Boeing 747 or Airbus A340, which need more visual reference. Also, for night operations, you must have at least runway edge lights and runway end lights. If the runway has runway edge and centre line lighting, the minimum becomes 200/250 metres, again with the higher value for category D. If the runway has runway edge and centre line lighting AND multiple RVR information — meaning you have RVR readings from several points along the runway — the minimum goes down to 150/200 metres, with the higher value for category D. Now, there are four important notes attached to this table. Note 1 — we already covered: the higher value in each pair applies to category D aeroplanes. Note 2 — for night operations, you need at least runway edge lights and runway end lights. Note 3 — this is a key operational flexibility: the reported RVR or visibility value that represents the initial part of the take-off run can be replaced by pilot assessment. So if the reported RVR at the start of the runway is below limits, but you as the commander can actually see that the visibility is better, you can use your own assessment. Note 4 — the required RVR value must be achieved for all of the relevant RVR reporting points along the runway, except as allowed by note 3. So if you have multiple RVR sensors, every one of them must meet the minimum, unless you're using pilot assessment for the initial part. Now, let's move to the second category of aeroplanes. These are multi-engine aeroplanes whose performance is such that they cannot comply with the earlier condition — meaning, if a critical engine fails during take-off, they cannot guarantee either stopping or continuing to 1500 feet while clearing obstacles. For these aeroplanes, there may be a need to re-land immediately after take-off and to see and avoid obstacles in the take-off area. These aeroplanes may still be operated, but with different take-off minima. The operator must base the minima on the height from which the one-engine-inoperative net take-off flight path can be constructed. That height is the point above the runway where you can still guarantee obstacle clearance with one engine out. The RVR minima used may not be lower than either of the values given in Figure 5.2 or Figure 5.3 — so you take the higher of the two figures. Finally, there's a critical rule for the commander: When reported RVR or meteorological visibility is not available, the commander shall not commence the take-off run unless it can be determined that the actual conditions — what you can see with your own eyes — satisfy the applicable take-off minima. You cannot simply assume it's okay; you must positively determine that the visibility meets the required minimum. So to summarise: you have two classes of multi-engine aeroplanes — those that can stop or climb to 1500 feet after an engine failure, and those that cannot. Each has its own minima table. The minima depend on the runway facilities available, whether it's day or night, and your aircraft category. And if no RVR report is available, you as commander must personally verify the actual visibility meets the minima before starting the take-off roll.