Commercial pilot · ACS CA.VIII.B · Instructor lesson plan
Pressurization
Student pack: Train: Pressurization · Full lesson: Prepare guide
1 · Objective
By the end of this lesson your student can explain pressurization in their own words and apply it to a realistic flight, to the ACS standard for CA.VIII.B.
Why it matters for safety: In a pressurized airplane at high altitude, a decompression gives the pilot seconds to a few minutes of useful consciousness. Pilots have been lost to slow leaks they never noticed. The response has to be automatic: mask on first, then descend, then think.
2 · Assign before the lesson
Pre-work: the free Train pack, Pressurization. How pressurization keeps the cabin low, how it fails, and what to do in the seconds after a decompression.
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Pack: pilotprep.pro/train/cpl/pressurization · Full lesson: pilotprep.pro/prepare/cpl/pressurization
3 · Teach sequence
Key points to land
- Pressurization pumps air into a sealed cabin (usually engine bleed or turbocharger air) and controls the cabin altitude by letting it out through an outflow valve.(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization))
- Differential pressure is the difference between cabin and outside pressure; the structure has a maximum, protected by a safety (relief) valve. A dump valve releases it all.(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization))
- Decompression types: explosive (under about half a second), rapid (a few seconds), gradual (slow, the most insidious because you may not notice).(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization); AC 61-107, Aircraft Operations at Altitudes Above 25,000 Feet MSL and/or Mach Numbers Greater Than .75)
- Explosive decompression (under about half a second) is faster than the lungs can vent, so lung damage is possible; in a rapid one (about 1 to 10 seconds) the lungs vent faster than the cabin and hypoxia is the main danger; a gradual one may show only on the instruments. Rapid decompression can cut the time of useful consciousness roughly in half: masks on first, immediately.(AC 61-107, Aircraft Operations at Altitudes Above 25,000 Feet MSL and/or Mach Numbers Greater Than .75)
- After a decompression: oxygen on, then an emergency descent to a safe altitude (generally 10,000 feet or the minimum safe altitude), then deal with the cause.(Airplane Flying Handbook (FAA-H-8083-3C), Emergency Procedures)
- The warning is about cabin altitude, not the airplane's: it comes on when the cabin climbs above about 10,000 feet. At FL350 with a normal 6,000-foot cabin, no warning; at FL200 with an 11,000-foot cabin, an emergency.(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization))
- Brief passengers on masks: on themselves first, then help others.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.VIII.B.S3)
How it works
- Compressed air (from engine bleed, a turbocharger or a compressor) is sent into the cabin; the outflow valve, set by the controller, holds the cabin altitude you select (the isobaric range) and then limits the pressure to a maximum differential (the differential range). A typical system holds about an 8,000-foot cabin at the airplane's maximum cruise altitude.(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization))
- Operating it, per the POH: before takeoff, set the controller for the planned cruise cabin altitude and the landing field elevation, and a comfortable rate; in the climb, verify it's pressurizing and the gauges behave; in cruise, monitor cabin altitude, rate and differential; depressurize on or after landing as directed.(Your airplane's POH/AFM)
- The Part 91 rules (91.211(b)): above FL250, at least a 10-minute oxygen supply for each occupant for a descent; above FL350, one pilot at the controls wears a sealed mask, with the FL410 two-pilot quick-donning exception.(14 CFR 91.211)
- Gauges: cabin altitude, cabin rate of climb, differential pressure. A safety valve limits differential pressure; a negative-pressure valve prevents outside pressure from exceeding cabin pressure; a dump valve releases cabin pressure.(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization))
- Failure modes: a leak (a door seal, a window), a failed outflow valve or controller, a loss of the air source (an engine failure in some designs). The warning comes on as cabin altitude climbs, typically around 10,000 feet.(PHAK (FAA-H-8083-25C), Aircraft Systems (oxygen and pressurization))
Physiology
- Hypoxia is too little oxygen reaching the body. Hypoxic hypoxia comes from altitude; hypemic from carbon monoxide or blood loss; stagnant from poor circulation (including G-loads); histotoxic from alcohol or drugs.(PHAK (FAA-H-8083-25C), Aeromedical Factors)
- Symptoms vary by person and come on insidiously: euphoria, poor judgment, headache, tunnel vision, tingling, drowsiness, slowed reactions, cyanosis. Learn your own (an altitude chamber course helps).(AIM, Chapter 8, Medical Facts for Pilots)
- Time of useful consciousness shrinks fast with altitude: about 20-30 minutes at 18,000 feet, 3-5 minutes at 25,000, 1-2 minutes at 30,000, 30-60 seconds at 35,000. A rapid decompression can cut it roughly in half.(AIM, Chapter 8, Medical Facts for Pilots; AC 61-107, Aircraft Operations at Altitudes Above 25,000 Feet MSL and/or Mach Numbers Greater Than .75)
- Night vision degrades from as low as 5,000 feet; smoking, alcohol, fatigue and some medications lower your tolerance. A pulse oximeter shows trends but doesn't replace the rules.(AIM, Chapter 8, Medical Facts for Pilots)
- A rapid decompression brings a loud noise, fog in the cabin, flying debris, cold, and pain in ears and sinuses; trapped gas expands, and decompression sickness is possible at high cabin altitudes.(AIM, Chapter 8, Medical Facts for Pilots)
The response
- Masks on and oxygen flowing, crew first so you can help passengers; then an emergency descent per the POH; declare an emergency and squawk 7700.(Airplane Flying Handbook (FAA-H-8083-3C), Emergency Procedures; AIM, Chapter 6, Emergency Procedures)
- Level at a safe altitude (generally 10,000 feet or the minimum safe altitude if higher), assess the passengers, and land at a suitable airport. Use SRM: declare, use ATC, hand passenger briefing to a second pilot or capable passenger if you have one, and flying alone, put the airplane and the descent ahead of troubleshooting and passenger management until you're at a safe altitude.(Airplane Flying Handbook (FAA-H-8083-3C), Emergency Procedures; Risk Management Handbook (FAA-H-8083-2A))
- Be alert for a gradual decompression: a cabin altitude climbing slowly while you're busy. Scan the pressurization gauges like any other system.(AC 61-107, Aircraft Operations at Altitudes Above 25,000 Feet MSL and/or Mach Numbers Greater Than .75)
4 · Ask your student
In order: recall, then understanding, then applying it. Move up only when the answer shows it.
Recall · What does the outflow valve do?
A strong answer: It controls how much air leaves the cabin, setting the cabin altitude and its rate of change.
Understand · Why is a gradual decompression more dangerous than it sounds?
A strong answer: You may not notice it; hypoxia creeps in and impairs judgment before the warning gets your attention.
Apply · At FL250 there's a bang, the cabin fogs, and the warning sounds. Walk me through it.
A strong answer: Mask on and oxygen flowing first. Then an emergency descent by the POH, declare an emergency and squawk 7700, check the passengers have masks on, level at 10,000 feet or the minimum safe altitude, and land at a suitable airport.
Scenarios to talk through
Climbing through FL200, the cabin altitude reads 11,000 feet and is still rising. What do you do?
Sound decision: The cabin, not the airplane, is above 10,000 feet: masks on first; one quick, obvious check; and if the cabin isn't under control at once, start the emergency descent without delay; troubleshooting goes on during the descent, never before it. (The dump valve's normal use is depressurizing on the ground.)
A passenger complains of joint pain after a decompression. What might it be?
Sound decision: Decompression sickness: stay low, land, and get medical help; hyperbaric treatment may be needed.
A passenger asks why you're briefing masks when the cabin is pressurized. What do you say?
Sound decision: Because if pressurization fails at altitude, there are only moments to put on the mask: on yourself first, then help others.
5 · Common student errors
Troubleshooting before donning oxygen.
Why it matters: Useful consciousness may be seconds.
How to correct it: Mask first, always.
Ignoring the cabin-altitude gauge.
Why it matters: A slow leak goes unnoticed.
How to correct it: Include it in the scan.
Descending too slowly after a decompression.
Why it matters: Passengers without oxygen are at risk.
How to correct it: Emergency descent per the POH.
6 · Completion standard
- Your student answers each "Ask your student" question in their own words, up to the Apply level, without prompting.
- They talk through the scenarios and reach a safe, legal decision, explaining why.
- They complete the pack’s quick check and can say what they flagged.
Area trained? Close out with a practice oral focused on CA.VIII.B: pilotprep.pro/exam?exam=CPL&focus=CA.VIII.B
7 · References
- Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Aeromedical Factors; Aircraft Systems
- Aeronautical Information Manual (AIM), Chapter 8, Medical Facts for Pilots
- 14 CFR 91.211, Supplemental oxygen
- AC 61-107, High-altitude operations
- Commercial Pilot ACS (FAA-S-ACS-7B), Area VIII
- Your airplane's POH/AFM, oxygen and pressurization systems
- Airman Certification Standards, task CA.VIII.B
PilotPrep instructor lesson plan, from the Pressurization lesson (checked against current FAA sources 2026-11-13). A study and teaching aid, not FAA guidance; teach to your own judgment and the current ACS.