Lecture 9: Ecological Factors & Aircraft

Performance

AIRCRAFT WEIGHT & PERFORMANCE

ecological factors

• Sometimes aircraft performance is limited by different ecological factors.

• As the awareness for protection of the environment and nature is increasing, the ecological factors limiting aircraft performance are becoming more and more significant.

What Are the Ecological Factors that Limit the

Aircraft Performance??

Ecological Factors that Limit the Aircraft Performance

The most common ecological factors that have greatest influence on aircraft performance are

a) Fuel Dumping : Release fuel before landing to reduce aircraft mass

b) Noise abatement procedures: Action that minimizes impact of aircraft noise

c) Bird Strikes: Birds collide with aircraft and cause serious damage.

a) Fuel dumping

• Why need to Dump the fuel??• Needed to meet landing weight limits or runway

length limit• System of fuel pumps and valves• Usually ejected from wingtips• Usually designed to allow the plane to go from max

take-off weight to max landing weight in 15 minutes or less.

Fuel dumping • Fuel dumping is common on both large commercial airliners

and military planes. • Many aircraft require the ability to dump fuel because of

landing weight restrictions imposed by the manufacturers (MLW) **AUW during landing must less than MLW.

• In other situations, an aircraft may be at an acceptable landing weight but forced to make an emergency landing at a runway that is too short (LDR<LDA).

• It may be necessary to dump fuel to reduce the plane's weight low enough in order to make a safe landing on a shorter field.

Boeing 777 dumping fuel in flight from its wingtip

B-1B bomber dumping fuel

Commercial airliners as well as military aircraft are equipped with emergency fuel dump systems that allow them to release fuel in flight. On most aircraft, these systems are designed to dump fuel from both wingtips.

Fuel dumping

• A typical fuel dumping system employs a series of pumps and valves to eject fuel from the aircraft's wingtips.

• When activated from the cockpit, a fuel dump system often is capable of releasing thousands of pounds of fuel per minute.

• Most systems are sized to release fuel at a fast enough rate that the plane's total weight is reduced and < MLW in fifteen minutes or less.

Fuel dumping

• Modern aviation fuel comes in many varieties but all are derivatives of kerosene.

• Kerosene evaporates rapidly in the atmosphere and very little typically survives in liquid form to reach the Earth's surface.

• The exact evaporative characteristics of dumped fuel depends on a number of factors like the altitude at which it was released, the atmospheric temperature, and the dumping pressure.

• Kerosene dumped at high altitude on a warm day tends to evaporate fastest.

Regulations set up by FAA for fuel dumping

1. Fuel can only be dumped above a minimum altitude of 2,000 ft (610 m), to improve its evaporation.

2. Dumping aircraft must be separated from other air traffic by at least 5 miles (8 km).

3. **Pilot should reports ATC that he/she needs to dump fuel in order to get an aircraft down to its maximum landing mass. ATC then should guide the pilot to ensure that the aircraft receives the required separation during the process, and should divert the plane away from areas of heavy traffic.

B) Noise abatement procedures • Noise abatement (NA) is an action that minimizes impact

of noise at airport. • Most airport that are located very close to community have

number of regulations in place designed to reduce noise levels. These regulations include

• Aircraft may not fly at certain areas• Use or disuse of certain runways • Limiting the number of departures and arrivals per runway• Limit the maximum thrust allowed when flying over certain

areas; • Forbidden use of reverse thrust at night on some airports.

NAP impact to Aircraft Performance• Even, noise abatement procedures could minimize

noise effect, it is however give several disadvantages to airlines and airport:• Operational restrictions may limit an airport’s

capacity, further contributing to airport congestion and travel delays, and to higher airline operating costs.

c) Bird strikes

• Bird strikes is a collision between an airborne animal (bird) with an aircraft.

• Bird strikes especially near to airport has the big potential to cause serious aircraft damage and loss of human life.

• Every years there are many aviation accidents reported caused by bird strikes. Because of this, FAA directs any related airport to concern on bird hazard management .

c) Bird strikes

• Under bird hazard management, some prohibited areas• The most common reason for designating such areas is to

prevent bird strikes.

• Usually the departure and arrival routes may be tailored to avoid areas of high bird activity, but most regulations governing the hazard of bird strikes are concerned with techniques to be implemented to discourage birds from flying in areas around the airport, rather than restricting air traffic.