First, let's talk about diversion time — Page 47, Lesson 69

I want to walk you through the next part of operational procedures, starting with how we establish minimum flight altitudes and then moving into fuel policy. First, let's talk about diversion time. The operator must use either the actual diversion time or a diversion time based on the MEL — that's the Minimum Equipment List — generated serviceability status of the aeroplane, whichever is shorter. So if the MEL says the aircraft can only fly for a certain time before needing to land due to a system limitation, that shorter time becomes your diversion time limit. Now, establishment of minimum flight altitudes. The operator is required to establish minimum flight altitudes for all route segments to be flown which require terrain clearance. That means for every part of your route where you need to stay above the ground or obstacles, there must be a published minimum altitude. The altitudes themselves and the method of calculating them must take into account the performance requirements of EU-OPS parts F through I. That's the European regulation set that governs aircraft performance. The method of calculating these altitudes must be approved by the Authority — that's the national aviation authority that oversees the operator. And here's an important rule: if the minimum altitude specified by a state — say, the country you're flying over — is higher than the one the operator has calculated, the higher altitude is to be used. The most conservative value wins. When establishing the minimum flight altitude, the operator has to take into account five specific factors. First, the position accuracy of the aeroplane — how precisely you know where you are. Second, inaccuracies in the operation of altimeters — no altimeter is perfect, so you need a margin. Third, the characteristics of the underlying terrain — is it flat, mountainous, or does it have tall obstacles? Fourth, the probability of encountering adverse weather, such as severe turbulence and descending air currents, which could push the aircraft down. And fifth, inaccuracies in aeronautical charts — the maps you use may not be perfectly accurate. Then, when taking those points into account, further consideration must be given to three additional items. Corrections for temperature and pressure variations from standard values — because non-standard conditions affect your true altitude. ATC requirements — air traffic control may impose their own minimum altitudes. And any foreseeable contingencies along the planned route — things that could go wrong that you need to plan for. Now let's move to fuel policy. The operator is required to establish a fuel policy for flight planning and re-planning purposes. The goal is to ensure that every flight carries sufficient fuel for the planned operation and reserves to cover deviations from the planned operation. So you plan for the trip you intend to fly, plus extra fuel in case things change. The planning is to be based on procedures contained in the OM — that's the Operations Manual — and the operating conditions under which the flight is to be conducted. This will use data provided by the aeroplane manufacturer, or current aeroplane specific data resulting from a fuel consumption monitoring system. Operating conditions include realistic aeroplane fuel consumption, anticipated masses — that's the weight of the aircraft — expected meteorological conditions, and airspace restrictions. A commander — that's the captain — shall only commence a flight or continue a flight in the event of in-flight re-planning, if satisfied that the aeroplane carries at least the planned amount of useable fuel and oil to complete the flight safely. So the final decision rests with the commander, and you must be confident the fuel is adequate. The pre-flight calculation of fuel required is to include taxi fuel — that's fuel used to move on the ground — trip fuel — fuel for the planned flight from takeoff to landing — and reserve fuel. Reserve fuel consists of five components. Contingency fuel, which covers unforeseen variations from the planned fuel consumption. Alternate fuel, which is fuel to fly to an alternate airport if you can't land at your destination. Final reserve fuel, which is the minimum fuel you must have remaining upon reaching the alternate. Additional fuel if required by the type of operation, for example ETOPS — Extended-range Twin-engine Operations — which requires extra fuel for long overwater flights. And any extra fuel required by the commander — the captain can add more fuel at their discretion. For in-flight re-planning fuel calculation, the list is slightly different. You consider trip fuel for the remainder of the flight, and reserve fuel consisting of contingency fuel, alternate fuel, and final reserve fuel. Plus any additional fuel reserve required by the commander. Notice that taxi fuel and the ETOPS additional fuel are not listed here — that's because you're already airborne, so taxi fuel is already consumed, and ETOPS requirements would have been addressed before departure. Finally, the excerpt introduces the topic of Carriage of Persons with Reduced Mobility, or PRMs. PRMs are defined — and that definition will continue in the next part of the book.