All Weather Operations — Page 65, Lesson 100

I want to walk you through the take-off minima rules that apply when we're operating in low visibility. This is a critical part of All Weather Operations, and it's all about how much runway you need to be able to see before you can legally start the take-off roll. Let's start with the baseline table. The key idea is that the required RVR or visibility depends on how high above the runway you are at the point where you assume an engine fails. That height is called the "assumed engine failure height above the runway." If that height is less than 50 feet, you need a minimum RVR of 200 metres. If it's between 51 and 100 feet, you need 300 metres. Between 101 and 150 feet, 400 metres. Between 151 and 200 feet, 500 metres. Between 201 and 300 feet, 1000 metres. And if that assumed engine failure height is above 300 feet, you need 1500 metres. Now, note 1 says that 1500 metres also applies if you cannot construct a positive take-off flight path. That means if your performance calculations show that, even with one engine failed, you can't guarantee a safe climb-out profile, you're stuck with the 1500 metre minimum regardless of your engine failure height. Note 2 gives the pilot some flexibility. The reported RVR or visibility value that's representative of the initial part of the take-off run can be replaced by pilot assessment. So if the reported RVR at the runway threshold is lower than what you need, but you as the pilot can actually see the required distance from the cockpit, you can use your own assessment instead of the reported value. Now, there are exceptions that allow you to go lower than those baseline numbers. If the Authority approves it, an operator may reduce the take-off minima to 125 metres RVR for Category A, B, and C aeroplanes, or 150 metres for Category D aeroplanes. But this is only allowed if all of the following conditions are met. First, low visibility procedures must be in force at the airport. Second, the runway must have high intensity runway centre line lights spaced at 15 metres or less, and high intensity edge lights spaced at 60 metres or less, both in operation. Third, the flight crew members must have satisfactorily completed training in a flight simulator specifically for these low visibility take-offs. Fourth, a 90 metre visual segment must be available from the flight deck at the start of the take-off run. That means from the pilot's eye position looking forward, you must be able to see at least 90 metres of the runway ahead. And fifth, the required RVR value must have been achieved for all the relevant reporting points along the runway. There's an even lower tier. If the aeroplane uses an approved lateral guidance system, or an approved HUD or HUDLS for take-off, the operator may, again subject to Authority approval, reduce the take-off minima to an RVR less than 125 metres for Cat A, B, and C, or less than 150 metres for Cat D, but not lower than 75 metres. However, this is only permitted if runway protection and facilities equivalent to Category III landing operations are available. That means the airport must have the same level of safeguarding and equipment that you'd need for a full autoland in zero visibility. So to summarise: the baseline table gives you your minimum RVR based on engine failure height. You can go down to 125 or 150 metres if you meet five specific conditions. And you can go down to 75 metres if you have an approved guidance system and Category III-equivalent runway protection.