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Cabin pressurization is the active pumping of air into an aircraft cabin to increase the air pressure within the cabin. It is required when an aircraft reaches high altitudes, because the natural atmospheric pressure is too low to allow people to absorb sufficient oxygen, leading to altitude sickness and hypoxia. Hypoxia will result in loss of consciousness without emergency oxygen. That’s why the pilot will want a descent to an altitude where the aircraft can be safely operated without necessity of pressurization.

Loss of pressure on the flight deck or in the passenger cabin is already a serious emergency known as pressurization problem. A harmless pinhole under the pressure differences will generate a high-pitched sound as the air leaks out at supersonic speeds. Gradual or slow decompression is dangerous because it may not be detected. In this case a pilot makes a descent to a lower altitude. It is normally at around ten thousand feet. It is the controller’s job to arrange this procedure safely and quickly.

 

 

 

 

Explosive decompression(ED) refers to a sudden drop in the pressure of a system that occurs in less than 0.1 seconds. ED is a change in cabin pressure where the lungs can decompress faster than the cabin. Generally it results from some sort of material fatigue or engineering failure, causing a contained system to vent suddenly into the external atmosphere. This type of decompression is dangerous and often results in lung damage and unsecured items / debris flying around the cabin. If a window cracks and then breaks, anything not firmly fastened will be sucked out.

When explosive decompression happens, the aircraft will not ask for a descent clearance. It will immediately start an emergency descent. The pilots do their best to reach a lower height at which they and the passengers can survive. During this phase of the emergency a controller has to provide priority for emergency traffic and inform all other traffic about emergency descending aircraft giving its position and flight levels to the crew. Rapid decompression of commercial aircraft is extremely rare, but dangerous. People sitting next to a very large hole may be forced out or injured by flying debris.

Listening and Speaking Bank.

Unit 8B. Exercise 7-8.

Read the instructions and do the task.

 

VIDEO # 34

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1. Read the text answer the question:

What problems might an aircraft experience because of hydraulic system failure?

Several aviation incidents have occurred in which the control surfaces of the aircraft became disabled, frequently due to loss of hydraulic systems which provide necessary power to move and control the main aircraft components. An aircraft's loss of control surfaces, such as elevator, rudder, ailerons may result in uncontrollable speed and direction. Hydraulic problem with flaps, spoilers and low hydraulic brake pressure may lead to aircraft control difficulties; air and ground braking difficulty may result in a longer landing roll.

Possible brake overheating may take place and the aircraft may run off the runway. Sometimes undercarriage does not retract or extend down properly. Pilot would probably require the emergency equipment to stand by at the end of the RW. From a controller’s viewpoint such serious malfunctions are severe emergency cases, and the following actions should be taken: informing supervisor immediately, imposing radio silence in case a pilot declares emergency, alerting appropriate emergency services, Search and Rescue Team, etc.

Listening and Speaking Bank.

Unit 8C. Exercise 2-3.

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VIDEO # 35

Warm up. ¸ Watch a video and guess what we are going to discuss now.

 

1. Look through the text and think of a title. Then read the text and answer the questions.

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A review of accidents caused by fuel problems reveals that many power failures were due to use of improper fuel or careless servicing – fuelling aircraft from poorly filtered tanks.

Fuel can be contaminated with water, rust, sand, dust, micro-organisms and certain additives that are not compatible with the fuel, fuel systems materials and engines. The presence of any contamination in aircraft fuel system is dangerous. During freezing temperatures, water may turn to ice, stopping fuel flow; freezing at high altitudes may plug fuel screens. Moreover, the fuel may be contaminated with dust and sand through openings in tanks and from the use of fuel handling equipment that is not clean. What is more, certain oil companies, in developing products to cope with aircraft fuel icing problems use some substances known as additives. Some additives may be harmful to other parts of the engine with which they come in contact. Fuel contamination is considered to be one of the most serious problems nowadays that might lead to engine vibration. In such a case a pilot has to shut down the engine, otherwise it can cause the engine destruction.

additive / to reveal / specification / substances / harmful / to contaminate / compatible /