Class A - En Route — Page 464, Lesson 570

We’re moving into the en-route phase of the flight now, and I want to start with a rule that shapes how twin-engine aeroplanes cross oceans. You’ve heard of the 60-minute rule — the idea that a twin-engine jet must stay within 60 minutes of a suitable diversion airfield, in case one engine fails. But as aeroplanes became more reliable and efficient, that rule got extended. That extension is called ETOPS. ETOPS stands for Extended-range Twin-engine Operational Performance Standards. It’s a set of standards that lets twin-engine aeroplanes fly routes much farther from diversion airfields than the old 60-minute limit allowed. Before ETOPS, only aeroplanes with three or more engines could operate on those long over-water or remote tracks. ETOPS hugely increases the operational capability of twins. But here’s the key point — ETOPS isn’t automatic. The airline has to apply for it, and the appropriate aviation authority has to grant approval. To get that approval, the airline must know a greater range of performance parameters, and those parameters accompany the application and eventually get published in the operating manual. So the manual ends up containing extra data for three specific things: the Area of Operation, the Critical Fuel Reserves, and the Net Level-off Altitudes. Let me unpack those three. The Area of Operation is simply the geographic region the aeroplane is approved to operate in under ETOPS. Critical Fuel Reserves are the fuel you must carry to cover the worst-case diversion scenario — the fuel needed if an engine fails at the most critical point. And Net Level-off Altitudes — that’s the altitude the aeroplane can maintain, or level off at, after an engine failure, with the performance margins built in. These are the performance parameters the authority needs to see before granting approval. Now, what does an ETOPS approval actually buy you? Take a 120-minute approval, for example. That means the aeroplane can be up to 120 minutes flying time from a suitable diversion airfield. That greatly benefits flight tracks across the Atlantic Ocean. The route from Paris to New York, for instance, can now be flown direct by a twin jet aeroplane — something that wasn’t possible under the old 60-minute rule. The longest ETOPS approval currently is held by the Boeing 777. It has an approval of 180 minutes, with contingencies for 207 minutes over the Pacific. So that’s the current ceiling — 180 minutes standard, and up to 207 minutes with the contingency built in. And looking to the future, ETOPS may evolve into a newer system called LROPS. LROPS stands for Long Range Operational Performance Standards. The important difference is that LROPS will affect all aircraft, not just those with a twin-engine configuration. So it’s a broader standard that would apply across the fleet. Now, I want to shift to a couple of practice questions that follow this material — they’re about optimum altitude and the aerodynamic ceiling. These are the book’s practice questions, so let’s try them one at a time.