MRJT Additional Procedures — Page 120, Lesson 116

I want to walk you through a new topic now — MRJT Additional Procedures, specifically starting with Non-normal Operations and then moving into Fuel Tankering. Let’s begin with Non-normal Operations, and the first item here is a Gear Down Ferry Flight. A ferry flight is when you move an aircraft from one place to another without passengers or cargo — often for maintenance, repositioning, or delivery. A Gear Down Ferry Flight means the landing gear is extended and locked down for the entire flight, which is a non-normal configuration because it creates a lot of drag. The reference for this is CAP 697 MRJT1 Figure 4.6.1. The procedure says the data is for a Gear Down Ferry Flight with all engines operating, at a speed of 220 KIAS — that’s 220 knots indicated airspeed. Importantly, climb and descent fuel and time are already included in the figures, so you don’t need to calculate those separately. Let me walk you through Example 9 so you see how this works. We have a sector distance of 850 nautical miles, a wind component of 75 knots tailwind, a cruise altitude of FL 240 (flight level 24,000 feet), a landing weight of 40,000 kilograms, and an outside air temperature (OAT) of -43°C. You are asked to calculate the fuel in kilograms and the time in hours and minutes required for this trip. Then Example 10 gives you a trip distance of 550 NM, a wind component of 100 knots headwind, FL 260, landing weight of 53,000 kg, and OAT of -22°C. Again, you calculate fuel and time. The answers to both examples are on page 121 of the book. Now let’s move to Fuel Tankering — this is a fuel economy technique. The idea is simple: if the cost of fuel at your destination airfield is higher than the cost at your departure airfield, it can be economical to carry extra fuel — more than you need for the flight — because you’re buying it cheap at departure and using it later at the expensive destination, or for the return flight or another sector. The graphs used are CAP 697 MRJT1 Figures 4.8.1 and 4.8.2, which are the LRC (Long Range Cruise) or 0.74 Mach Fuel Tankering graphs. But there’s a catch: carrying extra fuel makes the aircraft heavier, so you burn more fuel just to carry that extra weight. The graphs help you figure out what percentage of that surplus fuel will be burned as a penalty. The book says these charts should only be used if the cruise altitude capability is not adversely affected by tankering — meaning you must still be able to reach and maintain your planned altitude despite the extra weight. To use the graphs, you need three inputs: - Trip distance in NAUTICAL AIR MILES (NAM) - Cruise pressure altitude - Landing weight WITHOUT TANKERING — that is, the weight you would land at if you carried only the fuel needed for the flight, not the extra tankered fuel. The book gives an example using Figure 4.8.1: for a trip of 1600 NAM at FL330 with a landing weight (without tankered fuel) of 42,500 kg, if you carry excess fuel, 13.2% of that excess fuel will be consumed as a fuel penalty due to the higher gross weight. Now, for fuel tankering to actually be economical, the fuel price at the destination must be greater than the break-even fuel price. That’s where Figure 4.8.2, the Fuel Price Differential Graph, comes in. It gives you the Break Even Fuel Price at the Destination Airport for any given Surplus Fuel Burn percentage and Fuel Price at the Departure Airport. The fuel price is quoted in cents per US gallon. Using the example: with a 13.2% Surplus Fuel Burn and a Departure Airfield Fuel Price of 100 cents, the Break Even Fuel Price at the Destination Airport is 116 cents. So if the destination price is above 116 cents, tankering saves money; if below, it doesn’t. Now let’s look at Example 11 to apply this. An aircraft is planned to fly a LRC at FL350, ISA -10°C (that’s 10 degrees below International Standard Atmosphere temperature), with an average gross cruise weight of 55,000 kg and a Landing Weight (Without Tankered Fuel) of 47,500 kg. The wind component is -30 knots — remember, a negative wind component means a headwind. The trip distance is 1600 NGM — that’s nautical ground miles, not air miles, so you’ll need to convert to NAM using the wind component before using the graph. You are asked to calculate: - a. The % Surplus Fuel Burn — that’s the percentage of the tankered fuel that will be burned as penalty. - b. The Break Even Fuel Price at the Destination Airport if the Fuel Price at Departure Airport is 75 cents per US gallon. So you’d use Figure 4.8.1 to find the surplus fuel burn percentage, then Figure 4.8.2 with that percentage and the departure fuel price to find the break-even destination price. That covers the core of these two procedures — Gear Down Ferry Flight and Fuel Tankering.