High Altitude Operations Flashcards

1
Q

High altitude operations allow for…

A

lower fuel consumption and avoidance of weather

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2
Q

oxygen mask prevent? but don’t help with?

A

prevent hypoxia but do not help with sinus and ear blocks or decompression sickness

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3
Q

pressurized air is generally obtained from…

A

from an aircrafts turbocharger or compressor section of turbine aircraft

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4
Q

pressurized air piston powered aircraft may use…

A

air supplied from each engine turbocharger through a sonic Venturi

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5
Q

pressurized air gas turbine powered aircraft

A

use air supplied from the compressor stage of the engine which is conditioned for the cabin

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6
Q

cabin pressurized system typically…

A

typically maintains a cabin pressure altitude of 8,000’

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7
Q

pressurization

A

prevents rapid changes of cabin altitude, pressure inside body exceeds that outside the body causing bloating, lower cabin altitudes reduce this effect but are only available to aircraft manufactured to withstand the stress

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8
Q

pressurization system permits

A

a reasonably fast exchange of air from the inside to the outside of the cabin to eliminate odors and remove stale air

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9
Q

aircraft altitude

A

actual height above sea level

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10
Q

ambient temperature

A

temperature in area immediately surrounding the aircraft

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11
Q

ambient pressure

A

pressure in area immediately surrounding aircraft

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12
Q

cabin altitude

A

cabin pressure in terms of equivalent altitude above sea level

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13
Q

differential pressure

A

difference in pressure between the pressure acting on one side of a wall and the pressure acting on the other side of the wall. In aircraft air-conditioning and pressurizing systems, it is the difference between cabin pressure and atmospheric pressure

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14
Q

cabin pressure control system provides

A

cabin pressure regulation, pressure relief, vacuum relief, and the means for selecting the desired cabin altitude in the isobaric and differential range

dumping of cabin pressure

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15
Q

what is used to accomplish functions of cabin pressure control system

A

cabin pressure regulator, outflow valve, and a safety valve

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16
Q

cabin pressure regulator controls

A

cabin pressure to a selected value in the isobaric range and limits cabin pressure to a preset differential value in the differential range

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17
Q

differential control is used

A

to prevent the maximum differential pressure, from which the fuselage was designed, from being exceeded

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18
Q

cabin air pressure safety valve is

A

a combination pressure relief, vacuum relief, and dump valve

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19
Q

the pressure relieve valve prevents

A

cabin pressure from exceeding a predetermined differential pressure above ambient pressure

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20
Q

vacuum relief prevents..

A

ambient pressure from exceeding cabin pressure by allowing external air to enter the cabin when ambient pressure exceeds cabin pressure

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21
Q

dump valve

A

flight deck controls switch actuates it

when placed to ram a solenoid valve opens, causing the valve to dump cabin air to satmosphere

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22
Q

what limits degree of pressurization and the operating altitude of the aircraft

A

fuselage design to withstand a particular max cabin differential pressure

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23
Q

cabin differential pressure gauge

A

difference between inside and outside pressure

24
Q

cabin pressure altitude

A

equivalent altitude inside of cabin
reduces physical strain on the pilot and pax bodies

25
Q

cabin differential pressure

A

difference in pressure between the cabin and the outside air

26
Q

sonic venturi

A

limits the amount of air taken from turbo by accelerating air to sonic speed creating a shock wave which acts as a barrier

air is very hot and must be run through a heat exchanger to cool it

after cooling air is sent to cabin via heating and ventilation outlets

27
Q

regulation

A

outflow valve - allows air to exit

safety/dump valve - if outflow valves dump will release excess pressure

vacuum relief valve - allows ambient air into cabin

28
Q

instrumentation

A

cabin/differential pressure indicator - like altimeter but has two references outside and cabin pressure

cabin rate of climb indicator - indicates rate of change in cabin pressure

29
Q

altitude at 8,000ft

A

pressure 10.9 psi

30
Q

altitude 28,000ft

A

pressure 4.8 psi

31
Q

define hypoxia

A

:lack of sufficient oxygen in the body cells or tissues caused by an inadequate
supply of oxygen, inadequate transportation of oxygen, or inability of the body tissues to use

i. at high altitudes, pressure of oxygen on lungs is reduced, thus, the ability for the body to absorb oxygen is reduced

32
Q

time of useful consciousness

A

the amount of time in which a person is able to effectively or adequately perform flight duties with an insufficient

altitude / standard ascent rate / after rapid decompression
18,000 20-30 minutes / 10-15 minutes
22,000 10 minutes / 5 minutes
35,000. 30-60 seconds / 15-30 seconds
50,000. 9-12 seconds / 5 seconds

33
Q

prolonged use of oxygen

A

can produce toxic symptoms such as bronchial cough, fever, vomiting, lowered energy

i. significant periods of time are required before this occurs (usually 1-2 days)

34
Q

decompression sickness

A

nitrogen in the body changing from liquid form to gaseous
state due to a dramatic reduction in surrounding atmospheric pressure
i. AIM 8-1-2 recommends for flights below 8000 ft (cabin pressure), minimum 12 hours for non-decompression dives, and 2 hours for decompression dives. for flights above 8000 ft, 24 hours minimum.

35
Q

91.211a - general

A

i. minimum crew must use oxygen between 12,500 and 14,000 (inclusive) for any period over 30 minutes
ii. minimum crew must use oxygen above 14,000 at all times
iii. all passengers must be provided with oxygen above 15,000

36
Q

91.211b - pressurized cabin

A

i. above FL250, minimum of 10-minutes of supplemental oxygen available for each passenger
ii. above FL350, at least one pilot must be wearing and using an oxygen mask; unless at or below FL410, if there are two pilots at the controls, and both have quick donning type mask that can be put on and working within 5 seconds
iii.even with quick donning masks, if one pilot leaves, other must wear and use oxygen until other pilot returns

37
Q

jet stream

A

(1) travels east at approximately 50-200 kts
(2) caused by large temperature differences aloft
(3) has a meandering path that is constantly changing
(4) closer to the equator in the winter, farther in the summer
i. general circulation patterns move south in the winter due to less heating activity

38
Q

clear air turbulence (CAT)

A

(1) :phenomenon of turbulence associated with high altitude winds, and not associated with
clouds
(2) can be caused by wind shear, mountain waves, low pressures aloft, etc
(3) difficult to forecast since there are no visual signs of it.

39
Q

supplemental oxygen overview

A

(1) whether portable or installed, oxygen is stored in high pressure tanks (usually around
1800-2200 PSI)
(2) 22 cu ft container will supply 4 people at 18,000 ft for up to 1.5 hours
(3) aviation oxygen should be the only oxygen to be used (100% oxygen)
i. industrial oxygen is not made for breathing, and has impurities in it.
ii. medical oxygen may contain to much moisture which could freeze at low temperatures
(4) oxygen systems require periodic refill, inspection, and servicing i. AF/D tell what airports have oxygen available
(5) oxygen duration charts allow calculations of time available based on passengers and system PSI

40
Q

supplemental oxygen continuous-flow

A

most common type of system for piston aircraft as well as for passengers in turboprop and jets.
(1) overview
i.simplicity keeps maintenance costs down, reduces malfunction possibility
ii. not adequate above 25,000 ft. (although certified up to 41,000
iii. designs may include constant-flow, adjustable-flow, altitude-compensated flow iv. available as built-in system, or portable system
(2) mask styles
i. oronasal rebreather - covers both nose and mouth, and includes a bag to allow reuse of exhaled oxygen
ii. cannula breathing device - oxygen is supplied to the nose only, allowing use of normal communication methods (not certified as high as oronasal rebreathers)

41
Q

supplemental oxygen diluter-demand/pressure-demand

A

supply oxygen only when the user inhales through the mask
(1) depending on altitude the supplied mixture of oxygen to cabin-air are automatically adjusted
(2) demand-type masks have a tight seal to avoid dilution by cabin air, and are safe up to 40,000 ft

42
Q

oxygen generators

A

(1) available on airliners, oxygen generators use a chemical reaction to produce oxygen for
a set amount of time.
(2) each passenger has an individual “supply” from a generator

43
Q

cabin pressurization

A

the compression of air in the aircraft cabin in order to maintain a cabin altitude lower than the actual flight altitude

most light aircraft compress air to the cabin via the turbocharger or an engine-driven pump

44
Q

pressurization components

A

i. an outflow valve keeps pressure constant by releasing excess pressure into the atmosphere
ii.a cabin altitude can be manually selected via a cabin altitude controller, and if needed regulated via a backup control to a safety dump valve
iii. vacuum relief valve prevents cabin pressure from becoming lower than ambient pressure in the case of a rapid descent
iv. a heat exchanger conditions the air before entry into the cabin

45
Q

maximum pressure differential

A

:maximum allowable difference between atmospheric pressure and cabin pressure
i.different for each aircraft (see POH)

46
Q

emergency / decompression

A

the inability of the aircraftʼs pressurization system to maintain its designed pressure schedule

47
Q

decompression overview

A

i.can be caused by a malfunction in the system, or by structural damage to the aircraft ii.may result in cabin fog due rapid cooling of relatively moist air
iii.decompression of small cabins is more critical than large cabins given same hole or conditions
(i) primarily due to differences in cabin volume

48
Q

3 types of decompression

A

i. slow decompression - may be difficult to detect. many systems include audible and visual warnings of high cabin altitudes
ii. explosive decompression - an extremely dangerous condition in which he aircraft decompresses faster than the lungs can decompress.
(i) typically occurs in less than 0.5 seconds (ii) lung damage can occur
(iii) flying debris may cause further injury
iii. rapid decompression - decompression that occurs quickly, but is slower than the rate at which the lungs can decompress.

49
Q

decompression recovery

A

i. use supplemental oxygen as quickly as possible ii. descend as quickly as possible to a safe altitude
(i) a balance between reaching a safe altitude, and taking care of the engine must be made (most significantly in piston engines)
High Altitude Operations - rev. 2/25/09
iii. see emergency descent below for procedure

50
Q

fuel vaporization

A

(1) at high altitudes engine driven fuel pumps may be subject to fuel vaporization
i. boost pumps are typically installed to address this situation

51
Q

severe turbulence

A

(1) as with any altitude, if severe turbulence is encountered, maintain appropriate airspeed, and attempt to keep wings level, and heading approximately correct
(2) accept changes in altitude and airspeed as long as pitch is relatively constant

52
Q

Preflight considerations

A

(1) when using an oxygen system, ensure properly operation by testing the system before
takeoff
(2) when using a pressurized system, refer to the POH to see what preflight actions are required before operation

53
Q

Emergency Descents

A

(1) in an emergency descent, the main objective is to lose altitude as quickly (and safely as
possible)
i. may be due to an inflight fire, cabin depressurization, etc.
(2) this objective must be balanced with the need to preserve the engine.
i. especially in Pistons, shock cooling can have significant detrimental effects
(3) Procedure
i. if necessary, don oxygen mask as soon as possible
ii. slow the aircraft to proper speeds to extend gear and flaps
iii. set propeller to high rpm (to help act as an aerodynamic brake)
iv. reduce power as much as practicable
v. if time permits, contact controller and notify of emergency descent for traffic avoidance purposes
vi. initiate a 30°- 45° turn to allow traffic clearing, reduce vertical component of lift, and maintain positive “G” loading on the aircraft
vii. through descent, ensure:
(i) airspeed does not exceed appropriate limitations (Vfe, Vle, Vne) (ii) engine temperature does not cool to rapidly
a. if necessary add power to keep temperature up

54
Q

Simulated de-pressurization

A

(1) possible symptoms of a slow leak de-pressurization
(2) upon simulated depressurization
i. fly the airplane!
ii. don oxygen masks asap
iii. refer to emergency descent procedures

55
Q

signs of hypoxia

A

confusion, restlessness, difficulty breathing, rapid heart rate, bluish skin, headache, anxiety