Resources and efficiency


FLYING AND THE ENVIRONMENT	BASICS	FLIGHT TRACKS	ACTIVE ENVIRONMENTAL PROTECTION	LINKS

Resources and efficiencyAirspace design and infrastructureProcedures and operationsVision

Resources and efficiency

The direct route is the shortest. That is why air routes are approximately 30 percent shorter than land routes. But not only is flying quicker, it is also usually more environmentally friendly. Today’s aircraft use around 70 percent less fuel than their predecessors did 40 years ago. The entire handling of air traffic is now 10 percent more efficient than it was 10 years ago. This means that the same air transport infrastructure can handle 10 percent more passengers and cargo than 10 years ago. Aviation has a load factor of approximately 75 percent, compared to 40-50 percent for trains and 30 percent for cars. Over the past 40 years, Co₂ emissions per flight in air traffic have been halved.

To be more specific: Modern aircraft use around 3.5 litres of kerosene per 100 passenger kilometres, while the new generation (Airbus A380 and Boeing 787) use even less than three litres (i.e. 78 passenger miles per U.S. gallon). This exceeds the performance capability of any car on today's market. Because kerosene prices are constantly rising, the air transport industry is keen to:

operate modern, fuel-efficient aircraft and promote technological advances
Shorten airways and reduce the burden on airports
implement the best operational procedures possible
push for alternative energies to be introduced in order to further reduce Co₂ emissions
examine the suitability of hydrogen-powered engines for use in aircraft engines in the near future (similarly to how they are used in fuel cells)

Significant savings in Co₂ can also be achieved through new, energy-efficient workflows. For example, aircraft at the gate can be parked with the main engines turned off; a small generator would provide energy for air-conditioning, on-board computers, lighting and cleaning services. A number of airports are currently working on electronic systems to provide these services. It is estimated that this would allow a medium-sized airport to eliminate approximately 190 tonnes of Co₂ emissions per year.

“I saw an aircraft dumping fuel…”
Passengers and residents in the vicinity of airports often report seeing an aircraft dumping fuel on approach to land. However, this does not happen in reality. Of all the commercial aircraft in use today, only a small number of large long-haul types (e.g. B747, A340, B777) have the technical capability to dump fuel in the air, and this is only done in exceptional or emergency situations. The white streaks that people see coming from the wings are simply vapour trails caused by condensation (also known as contrails). They occur because of the difference in pressure below and above the wing. At the points where the two areas of pressure meet, there is a drop in temperature, and any water present condenses. This also answers the question as to why these trails are not always visible. If the relative humidity is low, these trailing vortices are not visible.

When does fuel dumping actually occur?
A controlled jettison of fuel is performed by long haul flights which need to land unexpectedly shortly after take-off. Fuel has to be released because the difference between the maximum take-off mass and the maximum landing weight is too large. If a landing aircraft’s mass is too high, the landing gear and brakes will be over-challenged, and the landing distance could be too long and the aircraft damaged.

At what level is fuel dumped?
If an aircraft has to return to the airport and there is no imminent risk to passengers or aircraft, fuel is dumped in areas designated by the air traffic controller. There are no rigidly defined areas for dumping fuel. Areas are selected based on the traffic situation, population structure and ICAO requirements. The prescribed minimum level for fuel dumping is 6,000 ft (approximately 1,800 m above ground level). If this is not possible because of a technical error or because it is unclear what the problem is, the captain makes a decision.

What lands on the ground?
In recent years, several institutes and (environmental) organisations have conducted measurements. The objective was to analyse whether – or to what extent – kerosene falls on the ground. The results of all analyses showed that the environmental limits were not exceeded. In the case of an airspeed of 450 km/h and a total dumping rate using jettison valves of 1,600 kg/min as well as an assumed distribution range of 1 km, the fuel dumped was calculated at 0.2 g/m2. Each year, DFS records 40 such events. This works out at one situation per 27,000 take-offs that requires fuel dumping as there are approximately 1.1 million take-offs in commercial air transport.


07/06/2011	PRINT

PROTECTING THE ENVIRONMENT AT DFS LOCATIONS
DFS aims to handle air traffic as efficiently as possible and using as few resources as possible. This applies not only to our day-to-day work, but also to our buildings. Read more here!

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