Example 12 from the flight planning material — Page 120, Lesson 119

I want to walk you through Example 12 from the flight planning material. This is a practical calculation that ties together fuel planning and economic decision-making. We have an aircraft that is going to fly a cruise at Mach 0.74 at Flight Level 310, with an ISA deviation of plus 15 degrees Celsius — so the temperature is 15 degrees warmer than standard. The landing weight, which is the weight without any tankered fuel, is 40,000 kilograms. The sector distance is 1,050 nautical ground miles, and the wind component is plus 35 knots — that means a tailwind of 35 knots. From this data, we are asked to calculate two things. Part (a): the percentage surplus fuel burn. That is the extra fuel burned expressed as a percentage — likely compared to some reference or planned fuel burn. Part (b): the break-even fuel price at destination, given that the fuel price at departure is 85 cents per US gallon. The answer is to be given in cents per US gallon. Now, the answers to this example, along with Example 11, are on page 121 of the book. I don't have those answers in front of me, but the point here is to understand what the problem is asking. Let me define the key terms clearly. "Landing weight without tankered fuel" means the weight of the aircraft at landing if you do not carry any extra fuel beyond what is needed for the sector — tankered fuel is fuel carried beyond the requirement for the flight, usually to take advantage of cheaper fuel at the departure airport. "Sector distance" is the great circle distance of the route, measured in nautical ground miles. "Wind component" is the portion of the wind that acts directly along the track — positive means tailwind, negative means headwind. The "break-even fuel price at destination" is the price per gallon at the destination airport that would make it equally economical to buy fuel there versus tankering fuel from the departure airport. If the destination price is below that break-even figure, it is cheaper to buy fuel at destination; if above, it is cheaper to tanker from departure. So in this example, with departure fuel at 85 cents per US gallon, we need to find what destination price would make the total cost the same when considering the extra fuel burned due to carrying the tankered fuel — that extra burn is the surplus fuel burn percentage from part (a). This is a typical airline fuel management calculation. The percentage surplus fuel burn tells you how much extra fuel you consume per unit of tankered fuel carried, and that directly feeds into the break-even price calculation. That figure shows the area of operation definition, which is related context for these planning calculations. So to summarize: we have a specific flight condition — Mach 0.74 at FL310, ISA+15, landing weight 40,000 kg, sector 1,050 ngm with a 35 kt tailwind. From that we compute the surplus fuel burn percentage, then use that with the 85 cents per US gallon departure price to find the break-even destination price in cents per US gallon.