25
HPL — CHAPTER 25 · NOTES
Numbers & Mnemonics
by Capt. Pankaj Pahil
Human Performance & Limitations · Module J — The Exam ArsenalNumbers & Mnemonics
Chapter 25 — Every exam-critical figure and memory aid from the whole book, collected into master quick-reference tables. Memorise these cold — the DGCA paper is built from them.
How to use this chapter
These figures are drawn from every chapter of this book. Cover the right-hand column, recall the value, then reveal. Any number in a red pill is a killer item the examiner returns to again and again.
AThe Atmosphere & Altitude
| Parameter | Value |
|---|---|
| Troposphere top (average) | 13 km / 8.1 mi / 43,000 ft |
| Stratosphere reaches | over 100,000 ft |
| Troposphere holds | 75% of atmospheric mass |
| Composition N₂ / O₂ / Ar | 78.08% / 20.95% / 0.93% |
| Water vapour (variable) | 1 – 4% |
| ISA sea-level pressure | 1013.25 hPa = 760 mmHg = 29.92 inHg = 14.7 psi |
| ISA lapse rate | 1.98 °C / 1000 ft |
| Tropopause altitude | 36,090 ft |
| Isothermal temperature | −56.5 °C |
| Cabin altitude maintained | 6,000 – 8,000 ft |
| O₂ available: half / quarter of sea level | 18,000 ft / 36,000 ft |
| Compensatory reactions begin | 6,000 – 7,000 ft |
| Supplementary O₂ from | 10,000 ft |
| Physiological-Deficient Zone | 12,000 – 50,000 ft |
| Critical threshold (no O₂, unpressurised) | ~22,000 ft |
| Safe altitude on 100% O₂ | ~38,000 ft |
| Armstrong's Line (body fluids boil) | 63,000 ft |
| Partial Space-Equivalent Zone | 50,000 ft – 120 nm |
CThe Thin Air — Hypoxia, TUC & Decompression
| Parameter | Value |
|---|---|
| Night vision impaired from | 5,000 ft |
| Smoker at 7,000 ft equals a non-smoker at | 10,000 ft |
| Marked day hypoxia symptoms / descend | 10,000 ft |
| CO affinity for haemoglobin vs O₂ | > 200× |
| TUC — FL180 / FL250 / FL300 | 20–30 min / 3–5 min / 1–2 min |
| TUC — FL350 / FL400 / FL500 | 30–60 s / 15–20 s / 8–10 s |
| Rapid decompression effect on TUC | halves it |
| Donating blood before flying | 48-hour rule |
| Flying after (compressed-air) diving | 24-hour rule |
DPoisons & The Cabin
| Parameter | Value |
|---|---|
| Smoker's altitude penalty | 3,000 ft (10,000 ft feels like 13,000 ft) |
| Smoking O₂-capacity loss (pack/day) | 5 – 8% |
| Bottle-to-throttle | 24 hours |
| Alcohol metabolised (BAC drop) | ~0.015 per hour |
| BAC pilot-error spike threshold | 40 mg / 100 ml |
| Alcohol at altitude | 1 drink at 6,000 ft = 2 at sea level |
| Peak performance temperature | ~20 °C |
| Vibration — breathing / vision resonance | 1–4 Hz / 30–40 Hz |
EThe Senses — Vision & Hearing
| Parameter | Value |
|---|---|
| Dark adaptation — cones / rods (full) | ~7 min / ~30 min |
| Off-centre night viewing | look 15 – 20° to the side |
| Fovea / periphery photoreceptors | cones (day, colour) / rods (night) |
| Human audible range | 20 Hz – 20,000 Hz |
| Noise-induced hearing loss threshold | 80 – 90 dB (prolonged) |
F/GForces & The Fit Aviator
| Parameter | Value |
|---|---|
| Load factor at 45° / 60° bank (level turn) | 1.41 G / 2.0 G |
| Positive-G cascade | grey-out → black-out → G-LOC |
| BMI formula | weight (kg) ÷ height² (m²) |
| Normal BMI — men / women | 20 – 25 / 19 – 24 |
| Fly after dental work | 48 – 72 hours |
| Hypothermia — normal / mild / severe core | 98.6 °F / <95 °F / ≤82 °F |
H/IThe Mind Aloft — Psychology
| Parameter | Value |
|---|---|
| Information-processing chain | sensory → detection → perception → decision → response → feedback |
| Memory stores | sensory (<1 s) · short-term (~7 items) · long-term |
| Skill acquisition (Anderson) | cognitive → associative → autonomous |
| Sleep — NREM 2 share / REM onset | ~50% of sleep / 70 – 90 min in |
| Window of circadian low | ~03:00 – 05:00 |
✦The Mnemonics
Gas Laws"Bad Hens Cluck, Geese Dance" → Boyle · Henry · Charles · Graham · Dalton.
O₂ Halving"Half by Eighteen, Quarter by Thirty-Six" → half of sea-level O₂ at 18,000 ft, one-quarter at 36,000 ft.
Physiological ZonesP · PD · PS · TS → Physiological · Physiological-Deficient · Partial Space-equivalent · Total Space-equivalent.
SHELL ModelSoftware · Hardware · Environment · Liveware · Liveware — the human L at the centre.
Aim of HPLD · P · U · I → Describe · Predict · Understand · Influence.
Fitness Self-CheckI·M·S·A·F·E → Illness · Medication · Stress · Alcohol · Fatigue · Eating/Emotion.
The Dirty Dozen12 preconditions for error — communication · complacency · knowledge · distraction · teamwork · fatigue · resources · pressure · assertiveness · stress · awareness · norms.
Editor's note — verify against the live syllabus
Every figure here is compiled from this book's chapters. Before an exam, cross-check any borderline value against the current DGCA CAR/AIC, as published figures are periodically revised.
✦ END OF CHAPTER 25 ✦
Capt. Pankaj Pahil
Reinforce Chapter 25: Numbers & Mnemonics
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