EU-OPS 1 - Extract 1 — Page 12, Lesson 16

We’re starting a new topic now: the operational rules for centre of gravity, straight from EU-OPS 1. This is the regulation that governs how we actually run mass and balance in day-to-day airline operations, so let’s get into it. First, the big idea. Every aircraft has a certificated centre of gravity envelope — that’s the official, approved range of CG positions within which the aircraft is certified to fly. But here’s the catch: that envelope assumes a perfect, known load distribution. In real operations, we don’t always know exactly where every passenger sat or how the fuel sat in each tank. So the regulation says this: unless you apply seat allocation — meaning you assign specific seats to specific passengers — and unless you account accurately for the effects of the number of passengers per seat row, of cargo in individual cargo compartments, and of fuel in individual tanks in your balance calculation, then you must apply operational margins to the certificated envelope. Let me unpack that. The certificated envelope is the theoretical limit. The operational envelope is what you actually use, and it’s the certificated envelope shrunk by margins. Those margins exist to absorb the uncertainty in your assumed load distribution. The regulation is explicit: in determining the CG margins, you must consider possible deviations from the assumed load distribution. In other words, if you assume passengers spread evenly but they all pile into the front rows, that’s a deviation — and your margin has to cover it. Now, if you choose free seating — that is, passengers sit wherever they like — the operator must introduce procedures to ensure corrective action by flight or cabin crew if extreme longitudinal seat selection occurs. Longitudinal means along the length of the aircraft, fore and aft. So if everyone crowds to the front or the back, the crew has a procedure to correct it, like moving people. And here’s the key regulatory point: the CG margins and the associated operational procedures, including your assumptions about passenger seating, must be acceptable to the Authority — that’s the national aviation authority that oversees the operator. Then we move to subparagraph (d)2, the in-flight centre of gravity. This is a separate requirement on top of the first one. The operator must show that the procedures fully account for the extreme variation in CG travel during flight caused by two things: passenger and crew movement, and fuel consumption or fuel transfer. So it’s not enough to get the CG right at the gate. You have to prove that your procedures handle the worst-case shift of the CG while the aircraft is actually flying — people getting up and walking around, and fuel burning off or being moved between tanks, which changes the CG as the flight progresses. Now, the second part of this extract is a completely different piece of regulation — it’s Appendix 1 to OPS 1.620(f), and it defines the area for flights within the European region. This is a geographic definition used for a specific operational rule. For the purposes of OPS 1.620(f), flights within the European region — other than domestic flights — are flights conducted within an area bounded by rhumb lines between a list of points. A rhumb line is a line of constant bearing — it crosses all meridians at the same angle. So the boundary is defined by straight lines on a Mercator-style projection between these coordinates. Let me read them out. We start at N7200 E04500 — that’s 72 degrees north, 45 degrees east. Then to N4000 E04500 — 40 north, 45 east. Then N3500 E03700 — 35 north, 37 east. Then N3000 E03700 — 30 north, 37 east. Then N3000 W00600 — 30 north, 6 west. Then N2700 W00900 — 27 north, 9 west. Then N2700 W03000 — 27 north, 30 west. Then N6700 W03000 — 67 north, 30 west. Then N7200 W01000 — 72 north, 10 west. And finally back to the start, N7200 E04500. So that polygon — running from the high Arctic down the eastern edge, across the Mediterranean and North Africa, out into the Atlantic, and back up — that is the European region for the purposes of this rule. And it’s depicted in Figure 1, which shows the European region on a map. So to tie it together: the first part of this extract is about how you must protect the CG envelope with operational margins and procedures, both on the ground and in flight. The second part is a precise geographic definition that other operational rules will reference. Both are the kind of regulatory detail you’ll be expected to know cold as a professional pilot.