Medium Range Jet Transport (MRJT) Detailed Flight Planning — Page 96, Lesson 89

I want to walk you through a detailed flight-planning example for the Medium Range Jet Transport, or MRJT. This is a worked example that will test how you apply the climb data, and it introduces the integrated range tables that are central to cruise fuel planning. Let’s start with Example 2. The problem gives you the following conditions: the airfield elevation is 3000 feet, the mean wind component is a 30-knot headwind, the brake release weight is 59 000 kilograms, the cruise pressure level is 35 000 feet, and the outside air temperature, OAT, is minus 62 degrees Celsius. Your job is to find the missing values: the time in minutes, the fuel burn in kilograms, the nautical air miles (NAM), the nautical ground miles (NGM), and the true airspeed (TAS) in knots. The answer is on page 104 of the book, so you can check your work later. Now, the real focus here is the Cruise/Integrated Range Tables. These tables are found in the CAP 697 MRJT1 document, on pages 25 through 68. They cover three cruise methods: Long Range Cruise (LRC), 0.74 Mach cruise, and 0.78 Mach cruise, plus a Low Level 300 KIAS cruise. The method for extracting data is the same for all of them. Here’s the key principle: these tables use a difference principle. You take two gross weights, and the difference between them is the fuel weight used for a sector. The corresponding difference in the tabulated distance gives you the still air distance for that weight of fuel. That’s critical because any ground distance affected by a wind component must first be converted to a still air distance before you can use the table. For convenience, gross weights are tabulated at 100-kilogram intervals, so you can extract values without interpolation. For example, using page 25 of CAP 697 MRJT1, a gross weight of 51 500 kilograms gives a cruise distance of 3093 nautical air miles. Conversely, a cruise distance of 4420 nautical air miles corresponds to a gross weight of 59 600 kilograms. The true airspeed, or TAS, is tabulated differently depending on the cruise method. For the 0.74 Mach and 0.78 Mach tables, the TAS is listed at the top of each pressure altitude page. For Long Range Cruise, the TAS is found adjacent to the gross net weight figure in the table. Also, note that there are corrections to fuel flow and TAS below each table for operations at non-standard temperatures. So if your OAT isn’t standard for that pressure altitude, you’ll need to apply those corrections. Finally, a general guideline: there are three main cruise methods. Long Range Cruise, where TAS is a function of aircraft mass, and then 0.74 Mach and 0.78 Mach, which are constant Mach number cruises. The integrated tables handle all of them, but you need to know which method you’re using to pick the right page and extract the correct TAS. So, to summarise: for Example 2, you’ll use the climb data tables to find the time, fuel, NAM, NGM, and TAS from the given conditions. Then, for the cruise phase, you’ll use the integrated range tables with the difference principle, remembering to convert any wind-affected ground distances to still air distances first. And always check for non-standard temperature corrections.