High Altitude Operations
High Altitude Operations
High Altitude Operations
Objective: the student will be introduced to pressurization of an airplane as well as be introduced to oxygen systems.
Completion Standards: the student will be able to explain the pressurization system and what decompression is. The student will also be able to explain supplemental oxygen regulations. The student will be able to explain the oxygen system.
References: part 91, PHAK ch 7, AIM, Oxygen equipment brochure
Equipment: White Board and markers, iPad/ computer
IP’s Actions:
Assess student
State the objective and completion standards
Writes down references
Provide attention getter
Present content
Assessment
Assign Homework
SP’s Actions:
Take notes
Ask Questions
Introduction:
(Attention Getter) : altitude is fun until its not… especially when not pressurized
Motivation: (Discuss purpose for lesson and relate to Attention getter)
Overview:
Regulatory requirements for use of oxygen
Physiological hazards associated with high altitude operations
Pressurization
Oxygen Systems
Problems associated with rapid decompression and corresponding solutions.
Content:
Regulatory requirements for use of oxygen.
Part 91.211
(a) General. No person may operate a civil aircraft of U.S. registry -
(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;
(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and
(3) At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen.
(b) Pressurized cabin aircraft.
(1) No person may operate a civil aircraft of U.S. registry with a pressurized cabin -
(i) At flight altitudes above flight level 250 unless at least a 10-minute supply of supplemental oxygen, in addition to any oxygen required to satisfy paragraph (a) of this section, is available for each occupant of the aircraft for use in the event that a descent is necessitated by loss of cabin pressurization; and
(ii) At flight altitudes above flight level 350 unless one pilot at the controls of the airplane is wearing and using an oxygen mask that is secured and sealed and that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude of the airplane exceeds 14,000 feet (MSL), except that the one pilot need not wear and use an oxygen mask while at or below flight level 410 if there are two pilots at the controls and each pilot has a quick-donning type of oxygen mask that can be placed on the face with one hand from the ready position within 5 seconds, supplying oxygen and properly secured and sealed.
(2) Notwithstanding paragraph (b)(1)(ii) of this section, if for any reason at any time it is necessary for one pilot to leave the controls of the aircraft when operating at flight altitudes above flight level 350, the remaining pilot at the controls shall put on and use an oxygen mask until the other pilot has returned to that crewmember's station.
Part 135.89
(a) Unpressurized aircraft. Each pilot of an unpressurized aircraft shall use oxygen continuously when flying -
(1) At altitudes above 10,000 feet through 12,000 feet MSL for that part of the flight at those altitudes that is of more than 30 minutes duration; and
(2) Above 12,000 feet MSL.
(b) Pressurized aircraft.
(1) Whenever a pressurized aircraft is operated with the cabin pressure altitude more than 10,000 feet MSL, each pilot shall comply with paragraph (a) of this section.
(2) Whenever a pressurized aircraft is operated at altitudes above 25,000 feet through 35,000 feet MSL, unless each pilot has an approved quick-donning type oxygen mask -
(i) At least one pilot at the controls shall wear, secured and sealed, an oxygen mask that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude exceeds 12,000 feet MSL; and
(ii) During that flight, each other pilot on flight deck duty shall have an oxygen mask, connected to an oxygen supply, located so as to allow immediate placing of the mask on the pilot's face sealed and secured for use.
(3) Whenever a pressurized aircraft is operated at altitudes above 35,000 feet MSL, at least one pilot at the controls shall wear, secured and sealed, an oxygen mask required by paragraph (b)(2)(i) of this section.
(4) If one pilot leaves a pilot duty station of an aircraft when operating at altitudes above 25,000 feet MSL, the remaining pilot at the controls shall put on and use an approved oxygen mask until the other pilot returns to the pilot duty station of the aircraft.
Physiological hazards associated with high altitude operations.
Hypoxia
Types
Hypoxic hypoxia
A result of insufficient oxygen available to the body as a whole.
Lack of oxygen
Hypemic Hypoxia
when the blood is not able to take up and transport a sufficient amount of oxygen to the cells in the body.
Not enough Blood
Caused by anemia
Lower red cell count
Hemoglobin is unable to transport oxygen
CO poisoning
Stagnant hypoxia
Not flowing
Oxygen rich blood doesn’t move
Leg/ Arm falling asleep
Histotoxic hypoxia
Normal oxygen transport
Unable to make use of it
Alcohol induced
One ounce can increase physiological altitude (2,000’)
Symptoms
Cyanosis (blue fingernails and lips)
Headache
Decreased response to stimuli and increased reaction time
Impaired judgment
Euphoria
Most dangerous
May feel like normal
Visual impairment
Drowsiness
Lightheaded or dizzy sensation
Tingling in fingers and toes
Numbness
Treatment
Reduce altitude
Time of useful consciousness
Pressurization
Sealed system
Allowed air to com in and lets the air go slowly
Uses Bleed Air
What does the system include
Cabin pressure regulator (CPR) — controls cabin pressure. If we reach the maximum difference, an increase in outside altitude will result in an increase inside.
Outflow valve — keeps pressure constant by regulating flow of compressed air.
Safety valve — combination of a pressure relief, vacuum relief, and a dump valve.
Pressure relief — prevents cabin pressure from exceeding a predetermined differential pressure above ambient pressure.
Vacuum relief — prevents ambient pressure from exceeding cabin pressure by allowing external air to enter when ambient pressure exceeds cabin pressure.
Dump valve — dumps cabin air to atmosphere. Cockpit switch.
Instruments
Cabin differential pressure gauge — indicates the difference between inside and outside pressure.
Cabin altimeter — shows altitude inside the airplane
Cabin VSI – Rate
Oxygen Systems
Storage (Gas, Liquid, Solid)
Aviators Breathing Oxygen (ABO)
High Pressure- 1800-2000 PSI
Heavy
Low pressure – 400-700 PSI
Liquid Aviators Breathing Oxygen (LOX)
Liquid
900:1 Expansion
Weight and size savings
Stored at very cold temps -197 F
Sodium Chlorate Candles (Solid-State oxygen)
When heated to 350 F
Releases oxygen
600:1 expansion
One time use/ fire hazard
Molecular Sieve Oxygen Generators (MSOG)
Uses ambient air to supply oxygen to the plane
21% of oxygen we breath
Portable
Delivery
Continuous flow
Continuous flow of oxygen
Economical
Very wasteful
Used at 28,000’ or lower
Diluter Demand
Compensates for the short comings of continuous flow
User on-demand during inhalation
Stops when breathing out
Conserves oxygen
Used up to 40,000’
Pressure Demand
Provides oxygen under positive pressure
Forceful oxygen
Over inflate lungs
Altitudes above 40,000’
Masks and Cannulas
Nasal cannulas (18,000’)
Oral-nasal re-breather (25,000’)
Quick-don mask (40,000’)
Airline drop-down units (Dixie Cups) (40,000’)
Care and storage of high-pressure oxygen bottles.
Portable oxygen equipment must be accessible in flight if the airplane does not have a fixed installation.
Oxygen usually stored at 1,800-2,200 psi.
When the ambient temperature surrounding the cylinder decreases, the pressure within the cylinder will decrease—no reason to suspect supply depletion if you notice a drop in indicated pressure.
Fire danger —
materials that are nearly fire proof in ordinary air may be susceptible to burning in pure oxygen. Oils and greases may catch fire if exposed to pure oxygen and cannot be in oxygen systems.
Smoking is prohibited during any kind of oxygen equipment use.
Thoroughly inspect and test all oxygen equipment before each flight. Available supply, operational check, assure it is readily available. Do periodic inspections and servicing.
Problems associated with rapid decompression and corresponding solutions.
Decompression—
the inability of the pressurization system to maintain its designated differential pressure. May be caused by a malfunction in the pressurization system or structural damage to the plane.
Explosive decompression
Change in cabin pressure faster than the lungs can decompress (less than 0.5 seconds).
During explosive decompression, there may be noise, and one may feel dazed for a second.
Rapid decompression
Change in cabin pressure where lungs can decompress faster than the cabin (i.e. no likelihood of lung damage).
During most decompressions, the cabin will fil with fog (the result of the rapid change in temperature and change of relative humidity), dust, and flying debris.
Air will rush from the mouth and nose due to the escape from the lungs.
Differential air pressure on either side of the eardrum should clear automatically.
Exposure to wind blast and extremely cold temperatures may occur.
Solutions
Don oxygen masks. Emergency descent.
Top priority: reaching safe altitude.
Be aware that rapid descent from high altitude could result in cold shock in piston engines, and cylinder cracking.
For explosive decompression, the time to make a recovery before loss of useful consciousness is even less.
Conclusion
Regulatory requirements for use of oxygen
Physiological hazards associated with high altitude operations
Pressurization
Oxygen Systems
Problems associated with rapid decompression and corresponding solutions.
(Questions to assess student)
When is oxygen needed for part 91?
135?
What kind of o2 systems are there
How the pressurization system work?
HW:
Look over pressurization and supplemental oxygen