Fuel Policy and Fuel Monitoring — Page 38, Lesson 53

I want to walk you through two special fuel-planning procedures that are important for your ATPL studies: the Decision Point Procedure and the Isolated Aerodrome Procedure. Let's start with the Decision Point Procedure. The Decision Point Procedure is a technique used on longer flights where you identify a specific point along the route—the Decision Point—where you make a critical choice. At that point, based on the fuel remaining, you decide whether to continue to the scheduled destination or to divert to an en-route alternate. But here's the key: this procedure should not be attempted unless the departure fuel is sufficient to guarantee a reasonable expectation that there will be enough fuel remaining at the Decision Point to permit continuation to the scheduled destination. In other words, you need to start with enough fuel so that when you reach that Decision Point, you have a realistic chance of pressing on. The success of a Decision Point Procedure depends on whether unforeseen events have caused the contingency fuel allowance to be used. Those unforeseen events could include things like not being cleared to the optimum cruise level, or having to avoid weather. If those events haven't eaten into your contingency fuel, then the procedure works. The normal non-consumption of contingency fuel—which can be a considerable amount, usually at least 3% of the fuel between departure and the Decision Point—is what makes the Decision Point Procedure feasible and safe. Now, let's compare the fuel requirement for the Decision Point Procedure with the normal fuel requirements. The maximum fuel reduction you can achieve by using this procedure is the contingency fuel—that's 3% or 5% of trip fuel—between departure and the Decision Point. Alternatively, we can say that contingency fuel can be reduced down to that required between the Decision Point and the destination. So you're essentially shifting where that contingency fuel is allocated. Let me show you the geometry of this. shows a fuel graph, and illustrates the concept of insufficient fuel. But the specific Decision Point Procedure is shown in Figure 2.7, which I'll describe: you have the Departure Airport, then the Decision Point along the route, then the Destination Airport. From the Decision Point, you also have an En-route Alternate and a Destination Alternate available. Now let's move to the second special case: the Isolated Aerodrome Procedure. An 'Isolated' aerodrome is defined as an aerodrome for which there is no Destination Alternate. A good example is an island in the ocean, like Easter Island in the South Pacific. In this case, the aircraft might have to hold for longer than usual—for instance, if there's a blocked runway or a tropical storm passing through—with no option of diverting. Normally, reserves consist of contingency fuel, alternate fuel, and final reserve fuel. But in the case of an Isolated Aerodrome, there is no alternate, so there is no alternate fuel. Instead, for a jet or turboprop aircraft, the combination of final reserve fuel and additional fuel must comprise enough fuel to fly for two hours at normal cruise consumption after arriving at the destination aerodrome. The regulation that governs this is CS-OPS 1, and it specifies that the fuel must include: - Taxi fuel - Trip fuel - Contingency fuel - Additional fuel if required, but not less than: - For aeroplanes with reciprocating engines: fuel to fly for 45 minutes plus 15% of the flight time planned to be spent at cruising level, or two hours, whichever is less. - For aeroplanes with turbine engines: fuel to fly for two hours at normal cruise consumption after arriving overhead the destination aerodrome, including the final reserve fuel. So for a turbine engine aircraft—which covers most of the jets you'll fly—the requirement is two hours of fuel at normal cruise consumption after reaching the destination, and that two-hour figure already includes the final reserve fuel. Now, the excerpt ends with some practice questions. These are the book's practice questions—let's try them one at a time.