We start with OPS 1.610, "Loading, mass and balance." This is the master… — Page 1, Lesson 5

I want to walk you through the regulatory heart of mass and balance — this is the EU-OPS 1 Subpart J extract, and it's the legal skeleton that everything else in this book hangs on. These are the actual rules an operator must comply with, so let's take them one by one. We start with OPS 1.610, "Loading, mass and balance." This is the master requirement. It says an operator shall specify, in the Operations Manual, the principles and methods involved in the loading and in the mass and balance system that meet the requirements of OPS 1.605. And critically, this system must cover all types of intended operations. So the point here is that the operator can't just wing it — they must write down, in their Operations Manual, exactly how they load the aeroplane and how they manage mass and balance, and that written system has to satisfy the higher-level requirement in OPS 1.605. And it has to apply to every kind of operation they intend to do, not just some of them. Now we move to OPS 1.615, "Mass values for crew." This is about how you determine the dry operating mass — that's the mass of the aeroplane ready for service, including crew, but before passengers and cargo are added. The rule gives you three options. Option one: use actual masses, including any crew baggage. Option two: use standard masses, including hand baggage — and here are the numbers you must remember — 85 kg for flight crew members and 75 kg for cabin crew members. Option three: other standard masses acceptable to the Authority. So the operator picks one of these three methods. Then there's a second part to this rule, OPS 1.615(b). It says an operator must correct the dry operating mass to account for any additional baggage. And here's the important bit — the position of this additional baggage must be accounted for when establishing the centre of gravity of the aeroplane. So it's not just about the weight; it's about where that weight sits, because that shifts the centre of gravity, and that's what you must track. Now the big one — OPS 1.620, "Mass values for passengers and baggage." This is where the detail really lives. Part (a) says an operator shall compute the mass of passengers and checked baggage using either the actual weighed mass of each person and the actual weighed mass of baggage, or the standard mass values specified in Tables 1 to 3 — those tables are in the full regulation, and we'll get to them. But there's an exception: where the number of passenger seats available is less than 10. In those small aeroplanes, passenger mass may be established by a verbal statement by, or on behalf of, each passenger, and then you add to it a predetermined constant to account for hand baggage and clothing. So for a small aircraft, you can ask each passenger their weight, and you add a fixed allowance for their hand baggage and clothing. And the rule closes by saying the procedure for when to select actual or standard masses, and the procedure to be followed when using verbal statements, must be included in the Operations Manual. So again — everything gets written down. Then part (b) deals with the actual weighing method. If you determine actual mass by weighing, the operator must ensure that passengers' personal belongings and hand baggage are included. And that weighing must be conducted immediately prior to boarding, and at an adjacent location. So the weighing has to happen right before they get on, and right next to the boarding point — that way the mass you record is the mass they actually carry onto the aeroplane. Let me pause there, because we've hit the end of this extract. The key thread through all three rules is this: the Operations Manual is the controlling document, and every method — actual, standard, or verbal statement — must be defined in it. And the centre of gravity is never an afterthought; any additional baggage must have its position accounted for. That's the discipline this regulation demands.