II. Put the words and word combinations in correct form into the gaps.

to be pressed of time   to plummet to initiate emergency descent  thin   to go off       to deteriorate readability  supplementary oxygen   to put on oxygen mask           slugging thinking to don oxygen mask to reach the safe altitude fainting    suffocation to sustain life dimmed vision   to evaluate the situation    to lose consciousness       to be exposed to   to collapse

1. When the pilot ………communication becomes complicated as it………..

2. Crew ………….to ……….. where people can breathe without …………….

3. In case of decompression oxygen inside the cabin becomes very………, so not to………… people have to …… … immediately.

4. Once the plane climbed 10 000 feet non-pressurization alarm……… in the cockpit.

5. Without supplementary oxygen at high altitude people suffer from ……… and can …………….

6. Explosive decompression at altitude 10 000 feet can result in……, …………, and ……….

7. After…………. pilots made up their mind to proceed to destination.

8. When the air pressure ………. inside the cabin pilots………… to react correctly.

9. Fuselage frame ……….. to constant pressure from inside and outside.

10. Aircraft flying at high altitudes have to be pressurized in order to……of passengers.

III. Name the synonyms of the words.

· Depressurization

· To lose consciousness

· To start emergency descent

· To put on oxygen mask

· To make readability worse

· Pressure drops

· To activate oxygen masks

· To come round

 

IV. Reply to the following questions. Your answer should contain the underlined words from the question.

1. What is necessary to do in order the passenger will regain consciousness?

2. What can deteriorate visibility in the cockpit?

3. Are oxygen masks deployed automatically?

4. Why should the oxygen mask be donned firstly by the parent and only then by the child?

5. What is recommended to do to avoid dehydration?

6. Why should ATC work in dimmed room?

7. What should be done in case engine stall alarm goes off?

8. What can be expected in case the captain collapses?

9. What forces is aircraft exposed to?

10. How much time does the person have to retrain consciousness in depressurized aircraft?

 

V. Complete the sentences with your own ideas.

1. Hypoxia can result in……………………

2. Slow decompression can lead to………..

3. Deteriorated visibility in the cockpit can cause………………

4. Explosive decompression can result from……………

5. Slugging thinking and dimmed vision can be caused by……….

 

VI. Discuss the questions below.

2. What are the airplanes pressurized for?

3. What situation is called depressurization?

4. What can cause depressurization on the board? (Divide the reasons into three factors: technical, human factor, outside factor)

5. What are the two types of depressurization? Which one is more dangerous?

6. At what altitudes does the risk of decompression exist?

7. What problems will the people experience in case of decompression?

8. What are the pilots expected to do in this situation?

9. What procedures have to be carried out in case of decompression over the mountainous area?

10. How can ATC assist the crew in case of decompression?

11. What catastrophes due to depressurization can you recall and describe?

VII. Read and discuss the text.

DEPRESSURIZATION

Depressurization is a rapid loss of atmospheric pressure due to damage of fuselage construction when the air inside the aircraft becomes as thin as outside and thus not appropriate for breathing. 

Pressurization problems can be caused by:

· Technical reasons ( malfunctioning of the air-conditioning system, electrical system failure, engine failure because engine supplies the work of air conditioning system, metal fatigue, glass fatigue )  

· Outside factor (bird strike on a windscreen on high level, detachment of engine that candamage the fuselage, encountering adverse weather conditions, such as turbulence, lightning strike that can cause significant damage of the construction of the aircraft)

· H uman factor (explosion of bomb, shooting, not properly closed door, poor maintenance service before departure)

· Any damage to the system could result in a leakage and consequently a rapid loss of cabin pressure.

Pressurization problems can cause an immediate danger to the aircraft, as the reduction of the cabin pressure will affect the crew and the passengers. The time during which people can retain consciousness without oxygen depends on the altitude flown, the size of the oxygen leak and the dimensions of the fuselage. It can vary from 4 to 30 seconds.

· There are two types of depressurization: rapid ( explosive ) and slow (gradual).

o A rapid decompression is a drop in cabin pressure in a matter of seconds. It occurs faster than the lungs can decompress the air. Pilots and passengers are short of time to don the oxygen masks, otherwise they will faint.

o A slow decompression is a gradual change of cabin pressure. It is complicated to determine it without automatic visual and aural warning system All of them are very dangerous as during explosive and rapid depressurization pilots are pressed of time to react while during slow one they can not even notice it and faint. Rapid decompression is easy to recognize as it is accompanied with a loud bang, sudden fogging of the air. During decompression at high altitude the temperature inside the aircraft will plummet to the ambient outside temperature with the danger of frostbite. So cabin pressure will instantly drop well below the freezing point while moisture in the air condenses to form of thick fog. Slow depressurization also poses the hazard as the pilots can not notice it and thus faint.

In all these critical conditions crew will have to retrain consciousness by donning the oxygen mask and initiating an emergency descent. 

So, people can suffer from

· Hypoxia (condition of oxygen starvation in the human’s body that can lead to sluggish thinking, dimmed vision, impaired motor skills- not able to coordinate body movements, loss of consciousness and even death)

· Decompression sickness (disease caused by the rapid loss of pressure of inhaled air mass which being dissolved in the blood starts producing bubbles that block the bloodstream. It can result in paralysis and death)

· Altitude sickness (disease state which is connected with oxygen starvation due to low partial oxygen pressure in the air at high altitudes; it can cause fatigue, nausea, sleepiness, dehydration of the body)

  In case of pressurization problems, the pilots

 1) will put on an oxygen mask and check if the oxygen masks were activated in passenger cabin automatically. In this case the headset is switched automatically to a cabin loudspeaker, with the pilot using the microphone in the mask which may reduce the readability to ATC.

2) Then they start emergency descent to the safe altitude (3000-4000meters) where people can breathe easily without masks. (set all thrust levers to idle, extend full speed brakes, descend at maximum permitted speed to MEA(FL 100) or minimum obstacle clearance altitude. In case of structural damage is suspected, reduce the speed as appropriate.)

3) Simultaneously pilots inform ATC about the situation. If ATC can’t be contacted they need to set squawk 7700 or transmit a distress message on emergency frequency.

4) After reaching the safe altitude the crew will evaluate the situation and make up decision to proceed to the nearest alternative or direct to the airport of destination at low altitude. This decision depends on the circumstances of the depressurization, the condition of the aircraft, and the condition of the passengers.

   Oxygen is supplied to the passenger for about 10-12 minutes which is enough to perform descent to safe altitude. But if the aircraft flies over the mountainous area where the range of mounts doesn’t allow pilots to get minimum safe altitude, descent will be extended and thus more oxygen will be necessary for sustaining life of the passenger on the board of the aircraft.

ATC has to react quickly:

· Acknowledge emergency on RTF(to receive pilot’s report as for emergency)

· Take all necessary action to vacate the airspace below affected aircraft and provide safe separation with other aircraft

· Impose radio silence if necessary

· Inform supervisor and other concerned services

· May be required to suggest a heading

· May be required to state the minimum safe altitude

· Emergency broadcast if necessary

· After emergency descent, request intentions: diversion, injuries, ACFT damage

Controller has to be aware of the fact that decompression will reduce quality of RTF communication due to oxygen mask. Some of the possible actions are:

· increase the volume of the receiver;

· try to keep aircraft within radar cover;

· have in mind the features of the existing radar system and refrain from attempting to transfer the aircraft to another sector.