Weather Information — Page 115, Lesson 93

I want to walk you through the supplementary information that can be included in weather reports, specifically concerning runway conditions. This is part of the broader Weather Information chapter, and it builds on the standard reports you've already learned about. Let's start with the types of runway surface conditions that get reported. You'll see terms like standing water — that covers conditions from damp, to wet, to water patches, or even flooded. Then there's snow, slush, and ice. These are all reported as part of the runway condition. Next, we have braking action. This is reported for three specific zones along the runway: the touchdown zone, the midpoint, and the stop end. The braking action is given as a code, and I'll show you the table that relates a measured coefficient to that code in a moment. There are also other runway surface conditions that might be reported — for example, if the threshold is displaced by 1000 feet due to work in progress. And you'll also see reports of obstructions and wind shear warnings. Let me give you an example of how this sounds on the radio: "Oxford 94, braking action medium due to heavy rain." That's a real-world transmission. Now, let's look at the braking action code table. This table was produced from data collected from operations on compacted snow and ice. It relates a measured braking coefficient to an estimated braking action, and then to a simple code for that braking action. I need to be very clear about one thing: the description "good" is a comparative value. It is intended to mean that aeroplanes should not experience directional control or braking difficulties when landing. But conditions would not be as good as on a clean, dry runway. So "good" here is relative to other contaminated surfaces, not to a perfect dry runway. Here is the table: - A measured coefficient of 0.40 and above gives an estimated braking action of Good, and the code is 5. - A measured coefficient of 0.39 to 0.36 gives Medium to good, code 4. - 0.35 to 0.30 gives Medium, code 3. - 0.29 to 0.26 gives Medium to poor, code 2. - And 0.25 and below gives Poor, code 1. One important note: the measured coefficient may be reported as a 2-digit code without the decimal. So instead of saying "coefficient 0.40", you might hear "coefficient 40". That's a common shorthand in operational reports. So to summarise: when you hear a braking action report, you'll get a code from 1 to 5, and you can use this table to interpret what that means for your landing performance. The lower the code, the worse the braking action, and the more caution you need.