The first in-flight weather briefing service we'll look at is called VOLMET — Page 541, Lesson 516

I want to walk you through the beginning of Chapter 29, which is all about how you get meteorological information once you're already airborne. Up to now in this book, you've been learning about weather briefing material you use during flight planning, before you even start the engines. But once you're in the air, you still need to know what the weather is doing, and you get that by tuning into specific frequencies on the aircraft's radio. The first in-flight weather briefing service we'll look at is called VOLMET. Let me break down that name for you. The first part, "vol," is the French word for flight. So VOLMET literally means meteorological information for aircraft in flight. That's exactly what it is — a dedicated service for pilots who are already airborne. Now, what exactly is a VOLMET broadcast? It's a ground-to-air radio transmission. The ground station sends it up to you in the aircraft. These broadcasts contain meteorological reports and forecasts, and they're transmitted on two frequency bands: the High Frequency band, which we call HF, and the Very High Frequency band, VHF. The important thing here is that these transmissions are in plain language — that means spoken English, not coded data. So you'll hear the information as spoken METARs, TAFs, and SIGMETs. Let me define those terms quickly: a METAR is the routine aviation weather report for an aerodrome, a TAF is the Terminal Aerodrome Forecast, and a SIGMET is a warning of significant weather phenomena that could affect aircraft safety. Here's a key operational point about VOLMET: the broadcasts transmit weather information for a number of different aerodromes, and they do it sequentially — one after another in a set order. That means if you need the forecast for a specific aerodrome that's relevant to your flight, you may have to wait for it to come around in the sequence. You can't just request it on demand; you listen to the broadcast cycle until your aerodrome's information is transmitted. Now, let's look at how VOLMET is actually operated. The book refers to a table, which is Figure 29.1, and that table is an extract from the United Kingdom Aeronautical Information Publication, specifically the GEN Section. The GEN Section is the general part of the AIP, which is the official publication containing all the information you need to fly in that country's airspace. This particular table contains a list of VHF VOLMET services and their associated radio frequencies for the United Kingdom and the near continent. So when you're flying in that region, you'd use this table to find the correct frequency to tune into for the VOLMET broadcast covering your area.