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Fuel management
Published in David Wyatt, Mike Tooley, Aircraft Electrical and Electronic Systems, 2018
When an aircraft takes off fully loaded with passengers and fuel, and then needs to make an emergency landing, it will almost certainly be over its maximum landing weight. Fuel has to be disposed of to reduce the aircraft weight to prepare for the emergency landing. A large aircraft such as the Boeing 747 can be carrying over 100 tonnes of fuel; this is almost 50% of the aircraft's gross weight. One way of burning off fuel and reducing aircraft weight is to fly in a high drag configuration, e.g. 250 knots with the gear down (speed-brakes will further increase the drag). Aircraft can be certified for landings up to the maximum takeoff weight (MTOW) in an emergency; however, overweight landings would only be made if burning off fuel exposed the aircraft to additional hazards. Some aircraft are installed with a fuel jettison, or fuel dumping system, Fig. 11.14. This provides a means of pumping fuel overboard to rapidly decrease the aircraft's weight. Fuel can normally be jettisoned with landing gear and/or flaps extended. Two jettison pumps are installed in each main tank, fuel is pumped via a jettison manifold to nozzle valves located at each wing tip trailing edge.
Handling-qualities specification – a functional requirement for the flight control system
Published in Mark B. Tischler, Advances in Aircraft Flight Control, 2018
Roger H. Hoh, David G. Mitchell
The concept of the MTE is to start with the total mission as defined by the user, and to break it down into elements that consist of handling-qualities tasks. As discussed earlier in this chapter, good handling qualities are only required for critical combinations of task and environment, and fall in the category of ‘nice to have, but not essential’ the rest of the time. Therefore, the MTEs must be defined to represent the critical tasks, where good handling is a necessity. The tasks that result are by definition not representative of normal operational activity. On the other hand, it is important to insure that MTEs do not require agility or precision that will never be required. Examples of MTEs for fixed- and rotary-wing aircraft are given below. Offset landings. Offset landings are commonly used (e.g. Reference 19) to force the pilot to be ‘in the loop’. This is intended to expose problems that would show up in turbulence and windshear where the pilot is unable to enter the flare in a stabilized condition. The required touchdown precision should be based on the shortest runways that would be used by the aircraft when at maximum landing weight.Accel/decel for helicopters. This MTE is taken from the helicopter MIL-Standard and is described in detail in Fig. 5. It is an aggressive maneuver and probably would not be required for civilian rotorcraft.
Work, and the Expertise of Workers
Published in Philip J. Smith, Robert R. Hoffman, Cognitive Systems Engineering, 2018
The introduction of team members also adds artifacts and dynamics to the work domain, to the extent that team members help create each other’s environment. The flight deck and the air traffic controller station both contain voice radio sets for communication, and the controller additionally has radar. Their teamwork actions employ carefully designed structures, including standard phraseology and published routes, so that any pilot can talk to any controller. These structures should be included in the analysis of each worker’s activities, but have not been historically an integral part of many work domain analyses (see Burns et al. 2004 for a discussion of how different analysts have approached such structures). While some may term them “intentional” dynamics or describe them as “soft” constraints on behavior, I would argue that (in aviation at least) these structures do not derive from the intentions of the worker, and operationally are just as “hard” as many physical aspects of the environment. A pilot may view an air traffic instruction as an exact target (particularly when he or she then overhears how it carefully steers them between other aircraft above and below), while some so-called physical limitations such as maneuvering speed, comfortable bank limits, or maximum landing weight can be overridden in an emergency.
Numerical analysis of hydroplaning behaviour by using a tire–water-film–runway model
Published in International Journal of Pavement Engineering, 2022
Xingyi Zhu, Yafeng Pang, Jian Yang, Hongduo Zhao
Because an aircraft has many specific characteristics, such as high velocity, high tire pressure, and short braking distance, only circumferential grooves were set up for obtaining a high drainage performance. The maximum takeoff and landing weight of A320 aircraft are 78,000 kg and 66,000 kg, respectively. In this model, the aircraft weight is the maximum landing weight since the hydroplaning behaviour occurs in landing stage. Moreover, there are two main landing gears which adopts single wheel group. The typical 46×17.0R20 tire structure of the A320 aircraft is displayed in Figure 2. Its geometry parameters are listed in Table 1.