The paper reviews the optimisation methods of the flight trajectory for airliners. In contrast to maritime navigation, where the shortest route (the orthodrome) is preferred, in air navigation, the brachistochrone is the optimal flight trajectory on the sphere or on the ellipsoid, considering the wind vector field (maximising the tail wind and minimising the head wind over the duration of the flight). The major impact of the wind on the flight trajectory results from the possible significant velocity at the normal cruise flight levels, which could reach 200 kts, or 40% of the aircraft true airspeed (TAS). Brachistochrone is independent of the flight performance optimisation (range versus speed), as computed by the flight management system. Whichever cost index (CI) is selected (and consequently, the cruise Mach number), the brachistochrone is the minimum time of flight trajectory at that target Mach number. In cruise flight, the minimum time of flight is also equivalent to the minimum fuel consumption. It concerns just the wind velocity field. All these qualify the brachistochrone as the greenest trajectory, the most fuel and emissions efficient solution relative to the atmosphere. The paper classifies the brachistochrone problems (2D, 3D and 4D brachistochrones, with or without flexible time of departure). Some numerical examples are provided. The overall optimal 4D trajectory considers many aspects, including safety, by minimisation of total costs and risks of the 4D trajectory.

This paper describes the air navigation techniques and drills used by Lancasters of the Pathfinder Force of Royal Air Force Bomber Command in early 1945. A brief description is given of the equipment and fixing aids available to the navigator and the environment in which he worked. The paper is based on the author's personal experience and with reference to the log and chart of an operation in which he took part. A running commentary on the navigational aspects of the operation is also given.

This Anderson Memorial Lecture was given to the Boscombe Down branch of the Institute on 19 February 2004. In the lecture Pinky Grocott, a distinguished navigator and past President of the Institute, recounts the history of the formation of Ferry Command set up to ensure the safe and efficient delivery of aircraft from North America to the UK during World War II. He then provides personal insights into his role as a young first-tour RAF navigator employed in the Command and describes the contemporary navigation practice.

This paper assesses the capability of GPS to provide the level of safety required for different aircraft flight navigation operations. It presents an analysis of the protection offered against potential catastrophic GPS failures at system and user levels. This is followed by an assessment of the different approaches to augmenting GPS for civil air navigation. Results show the inadequacy of GPS as a system for real-time safety critical use.

This paper deals with the modelling of airspace capacity in Europe by first considering the factors that affect controller workload and then using a model, aided by the appropriate analytical techniques, to make an estimate of airspace capacity. The results show that capacity can be estimated based on the combination of different types of air traffic movement in a sector. The model has been used to provide airspace capacity estimates and utilisation measures for ATC sectors in Europe.

Performance enhancement and cost reduction are driving forces in today's airline industry. In a world of cost pressures and escalating charges, research was conducted into better use of jet streams as a means of reducing costs. When operating on international airline routes, specific features of flight mechanics were adapted and tailored to fit a B747-200 aircraft, major emphasis being placed on intercepting, or avoiding where necessary, the high energy jet stream winds of the global weather system, adjusting flight profiles and modifying route structures. Operations were conducted both into wind and down wind, over a period of five years. Techniques employed show fuel may be saved regardless of the wind being a tailwind or headwind. Both fuel and time have a significant bearing on airline direct operating costs: savings of more than 1·1 percent being made on fuel and 0·786 percent on time. Limitations on using the techniques to gain maximum benefit are related to the high volume of aircraft blocking all major airways, and better quality, real time weather forecasts. The discussion looks at ways of improving the use of jet streams, as the world's airline traffic continues to grow. Forecasting upper winds, particularly in oceanic areas, needs to improve if airlines are to derive maximum benefits from these winds. There is need for further study utilising other aircraft types to ascertain what savings can result. Initial results were encouraging, using a Tristar L1011 aircraft.

Much has been written on the subject of aircraft collision risk and avoidance over the past 50 years. As a particularly interested aviator (a military and civilian pilot for the last 32 years), with a limited memory for the mathematics I studied at school, I have read several of these treatises with interest. I do, however, feel that the advent of modern, accurate navigation systems has changed the distribution of collision causes radically. We should be concentrating, not on the risks of aircraft accidentally flying into each others' paths, but on the risks of them deliberately doing so.

That statement requires explanation, of course. There is a risk of one pilot deliberately and willingly putting his aircraft in the path of another (a terrorist or suicide for example), but the risk is considerably less than that of a pilot who does it unwillingly, but equally deliberately.

Air Navigation — Status of Seaplanes — Alighting on the Sea.

Air Navigation — Status of Airships — Seaplanes — When Alighting on the Sea — Whether Merchant Vessels.