Iran CAO CPL Theory cheat sheet

ICAO Annex 1 - Personnel Licensing; Annex 2 - Rules of the Air; Annex 6 - Operation of Aircraft; Annex 8 - Airworthiness of Aircraft; Annex 13 - Aircraft Accident and Incident Investigation. National Civil Aviation Regulations issued by the Civil Aviation Organization of Iran (CAO) mirror these standards.

Right of way: aircraft of the same category converging at the same level - the one with the other on its right gives way. Power-driven heavier-than-air aircraft give way to gliders, balloons and airships; an aircraft landing or on final has right of way over aircraft on the ground; overtaking is done to the right.

Semicircular cruising levels by magnetic track: 000–179° odd thousands, 180–359° even thousands; VFR adds 500 ft. At and above the transition altitude, set 1013.25 hPa and use flight levels.

Documents carried on board: certificate of registration, certificate of airworthiness, crew licences with valid medical certificates, journey log book, radio station licence and, where applicable, operations manual, passenger list and cargo manifest.

A CPL requires a valid Class 1 medical certificate. ICAO validity is 12 months, reduced for older holders in single-pilot passenger operations; privileges may never be exercised on an expired or restricted medical.

ICAO VFR minima in controlled airspace: at/above 10 000 ft - 8 km flight visibility, 1500 m horizontal and 300 m (1000 ft) vertical from cloud; between 900 m and 10 000 ft - 5 km, 1500 m, 300 m; at/below 900 m - 1500 m visibility and clear of cloud.

Speed limit: 250 kt IAS below 10 000 ft in Class C, D and E airspace unless a higher limit is published for that airspace.

Annex 13: the operator notifies the nearest ATS unit immediately of an accident or serious incident and notifies the state of registry and state of the operator; the state of occurrence institutes the investigation.

Recency for carrying passengers: three take-offs and three landings within the preceding 90 days in the same type/class, and a type or class rating endorsed on the licence and current.

Four-stroke cycle: induction, compression, power, exhaust - one power stroke per two crankshaft revolutions per cylinder; the camshaft runs at half crankshaft speed to time the valves.

Mixture: rich at high power and low altitude for detonation margin and cooling; lean in cruise. An over-lean mixture raises cylinder head temperature and risks detonation and burnt valves.

Magneto check at run-up: maximum drop typically 150 rpm and maximum difference between magnetos 50 rpm. No drop at all, or an excessive drop, indicates an ignition fault - do not depart.

Constant-speed propeller: the governor meters engine oil to the hub; more oil pressure means coarser blade angle and lower rpm. On a single-acting system, loss of oil pressure drives the blades to fine pitch (high rpm).

Fuel grades: AVGAS 100LL is dyed blue, AVGAS 100 green, Jet A-1 colourless/straw. Never mix grades; drain and check for water and sediment before the first flight of the day.

Electrical: light twins commonly use 28 V DC, trainers 14 V DC; alternator + voltage regulator + bus bar. The loadmeter/ammeter shows alternator output or bus load, not battery state.

Hydraulics: engine-driven pump, reservoir, pressure regulator, accumulator for pressure surges and a relief valve; check pressure and fluid quantity before flight and after gear/flap operation.

Pressurisation: the outflow valve controls cabin altitude and rate of change; maximum differential pressure protects the structure; a cabin altitude warning typically triggers at 10 000 ft.

Landing gear: oleo (air-oil) strut absorbs landing loads, a shimmy damper prevents nosewheel oscillation, and differential braking provides steering; the park brake holds pressure for ground operations.

Pitot-static group: ASI uses pitot and static, altimeter and VSI use static only. A blocked pitot with a clear drain makes the ASI behave like an altimeter; a blocked static makes the ASI over-read in the climb, freezes the altimeter and zeroes the VSI.

Altimeter settings: QNH gives altitude above mean sea level, QFE gives height above the aerodrome reference datum, 1013.25 hPa gives pressure altitude and flight levels. Near sea level 1 hPa ≈ 27 ft.

ASI colour arcs: white arc = flap operating range (VSO to VFE); green arc = normal operating range (VS1 to VNO); yellow arc = smooth-air caution range up to VNE, the red radial line.

Turn indication: a standard-rate turn is 3°/s, a full circle in two minutes; the turn coordinator shows rate of turn plus an inclinometer for slip/skid, while the attitude and heading indicators rely on gyroscopic rigidity and precession.

Magnetic compass errors: turning error (under-reads turning through north, over-reads through south in the northern hemisphere), acceleration error (apparent turn to the north when accelerating in the northern hemisphere), plus deviation from aircraft magnetism. Read it in straight, level, steady flight.

VSI lag: the instrument lags the actual climb or descent by roughly 6–9 seconds and shows a brief reverse indication after an abrupt pitch change.

For a constant IAS, TAS increases by about 2% per 1000 ft of altitude; IAS is used against structural limits, TAS for navigation and ground speed for ETA and fuel.

The radio/radar altimeter measures true height above the terrain up to about 2500 ft and feeds the GPWS/EGPWS; it is independent of the QNH setting.

CG = Σ(mass × arm) / Σmass, with arms measured from the datum. Adding or removing mass moves the CG by Δmoment / total mass.

Mass limits: MTOM (take-off), MLM (landing), MZFM (zero fuel), and maximum ramp/taxi mass. MZFM = MTOM − take-off fuel mass and caps the empty mass plus payload.

%MAC = (distance of CG from LEMAC / length of MAC) × 100; the certified CG range is usually published as a percentage of MAC.

Forward CG: longer take-off run, heavier stick forces, greater longitudinal stability, slightly higher stall speed and more nose-down trim.

Aft CG: reduced static stability, lighter stick forces, lower stall speed, but easy spin entry with difficult recovery and a risk of exceeding the aft limit as fuel burns.

Fuel burn shifts the CG toward the CG of the fuel in the tanks: compute take-off and landing CG separately using zero-fuel mass and the fuel remaining in each phase.

Floor loading: respect the maximum running load (kg/m²) and maximum mass per seat or station; spread concentrated loads with plates and secure them with the correct tie-down points.

Position of the mass matters: the same mass has a larger CG effect the further it is loaded from the datum, so baggage and cargo arms must be taken from the loading manual, not estimated.

Density altitude = pressure altitude + 120 ft per °C above ISA. High density altitude, high mass, tailwind, upslope and soft or wet runway all increase take-off distance and reduce climb gradient.

V speeds: V1 decision speed, VR rotation, V2 take-off safety speed (35 ft at V2), VX best angle, VY best rate, VYSE single-engine best rate, VA manoeuvring, VNO, VNE, VFE, VLO/VLE.

VA decreases with mass: VA at mass m ≈ VA at MTOM × √(m/MTOM). Above VA a full or abrupt control deflection can exceed the limit load factor.

Wind components: headwind = wind speed × cos θ, crosswind = wind speed × sin θ, where θ is the angle between wind and runway. Compare with the maximum demonstrated crosswind.

Take-off and landing distances are quoted to a 50 ft screen height; apply the manufacturer's corrections for runway slope, wind, temperature, pressure altitude, contamination and runway surface condition.

Dynamic hydroplaning begins at approximately 9 × √(tyre pressure in psi) knots; for 36 psi this is about 54 kt ground speed. Viscous hydroplaning occurs at lower speeds on smooth, rubber-contaminated runways.

Balanced field length is the runway length at which the accelerate-stop distance equals the accelerate-go distance; it defines the maximum permissible take-off mass for that runway and conditions.

Climb gradient conversion: % gradient × 60.76 = ft/NM, so 3.3% ≈ 200 ft/NM. Obstacle clearance on departure is flown at VX, and the required gradient comes from the departure procedure.

QNH effect: flying from high pressure to low pressure without resetting the subscale leaves the aircraft lower than indicated - 'high to low, look out below'.

Fuel plan: taxi fuel + trip fuel + contingency (typically 5% of trip) + alternate fuel + final reserve (30 min holding at 1500 ft for turbine aeroplanes, 45 min for piston) + any extra fuel.

Wind triangle: WCA = arcsin(wind speed × sin(angle off track) / TAS); apply the correction into the wind. MH = TH ± variation (add west, subtract east) and CH = MH ± deviation.

Specific range (NM per kg) = TAS / fuel flow. Maximum endurance is at minimum fuel flow; maximum range is at maximum specific range, close to L/D max.

Point of no return (PNR) and equal time point (ETP): the point from which it takes the same time to continue to destination as to return to base; compute with the forecast wind and fuel flow in both directions.

An alternate is required when destination weather is at or below the planning minima or no instrument approach is available; check the fuel to the alternate with the forecast wind and the approach minima.

Flight plan filing: submit the ICAO plan to ATS before departure, typically at least 60 minutes for IFR flights; a departure outside the validity window requires amendment or a new plan.

Fuel quantity must be verified by gauges/dipstick before each flight and reconciled with the plan; unusable fuel and taxi fuel are not available for the trip calculation.

Run the log as time, leg distance, TAS, wind, ground speed, ETA and fuel remaining, and update it at each waypoint, recalculating fuel at destination and the alternate.

Mass, performance and fuel are interlinked: extra fuel increases mass, take-off distance and possibly shifts the CG, so re-check performance and balance after any fuel change.

Hypoxia signs: euphoria, impaired judgement, tingling, cyanosis, headache and visual loss. Time of useful consciousness is about 30–60 s at FL350 and 9–15 s at FL400 - oxygen first, then descend.

Hyperventilation mimics hypoxia (dizziness, tingling, cramps): treat as hypoxia with 100% oxygen, slow the breathing rate and check the cabin altitude.

Spatial disorientation: somatogravic illusion on acceleration, somatogyral illusion in a prolonged turn, the leans and Coriolis illusion. Trust the instruments and avoid abrupt head movements in IMC.

Vision: foveal vision gives detail and colour by day, rod/peripheral vision detects motion and dim light at night. Dark adaptation takes about 30 minutes and is degraded by smoking, hypoxia and white light.

Noise-induced hearing loss first affects the 3000–6000 Hz range (notch near 4000 Hz); use hearing protection and limit exposure to cockpit and ramp noise, which also causes fatigue.

Fatigue and circadian rhythm: alertness is lowest around 03:00–06:00 and 15:00–17:00 body-clock time; hydration, controlled rest and compliance with flight and duty limits are the mitigations.

Stress: physical stressors (noise, heat, vibration, hypoxia) add to psychological stressors (workload, threat). Performance peaks at moderate arousal and degrades sharply at high arousal.

CRM covers communication, leadership, situational awareness, decision-making, workload management and teamwork; a structured brief and assertive challenge break error chains.

Decompression sickness: nitrogen bubbles after rapid decompression or repeated altitude exposure give joint pain, chest or neurological symptoms that may be delayed; observe the flying-after-diving interval.

ISA: sea level 15 °C and 1013.25 hPa, lapse rate 1.98 °C per 1000 ft up to 36 090 ft, isothermal at −56.5 °C above; the tropopause height varies with latitude and season.

Altimetry: high to low, look out below - true altitude is lower than indicated when flying toward lower pressure. Cold air also puts the aircraft lower than indicated, so cold-temperature corrections are applied to approach minima.

QNH, QFE, QNE: QNH is the sea-level pressure giving altitude AMSL; QFE is the aerodrome pressure giving height above the aerodrome; 1013.25 hPa is used at and above the transition altitude.

Fog types: radiation fog forms on clear, calm, humid nights with a small temperature–dew point spread; advection fog forms when warm moist air moves over a cold surface; frontal fog forms at the frontal zone.

Thunderstorm hazards: severe turbulence, hail, lightning, downbursts and microbursts, icing above the freezing level and wind shear; the mature stage is the most hazardous and cells should be avoided by at least 20 NM.

Icing: clear ice from freezing rain or large supercooled drops, rime ice in stratiform cloud, mixed ice between; structural icing is most likely between 0 °C and −20 °C in visible moisture.

In the northern hemisphere, decreasing friction with height makes the wind veer (turn clockwise) and increase with altitude; Buys Ballot: with your back to the wind, low pressure is on your left.

METAR is the routine aerodrome observation, SPECI a special one, TAF the aerodrome forecast and SIGMET a warning of significant en-route weather such as turbulence, icing, thunderstorms or volcanic ash.

Wind shear and microbursts produce sudden airspeed and attitude changes; a microburst can generate downdraughts of up to 6000 ft/min. Go around from an unstable approach.

TVMDC: True to Magnetic applies variation (subtract easterly, add westerly); Magnetic to Compass applies deviation. Memory aid: variation east, magnetic least.

1 in 60 rule: a 1° tracking error produces 1 NM of lateral error in 60 NM; conversely 1 NM off track after 60 NM equals 1° of track error.

VOR: select the radial, the CDI shows course deviation and the TO/FROM flag shows the direction relative to the station; VOR radials are magnetic. DME reads slant range, which over-reads when close to the station.

NDB/ADF: relative bearing + magnetic heading = magnetic bearing to the station. ADF is affected by night effect, coastal refraction, static and thunderstorm interference.

A great circle is the shortest distance between two points; a rhumb line keeps a constant track. On a Lambert conformal conic chart the meridians converge toward the pole and the scale is nearly constant.

Wind triangle in flight: ground speed = distance / time; drift is the wind correction angle; crosswind component = wind speed × sin(angle between wind and track).

Log all times in UTC; the earth rotates 15° of longitude per hour, so local time depends on the time zone and any daylight-saving change.

GNSS RAIM needs at least five satellites for fault detection and six for fault exclusion; the receiver must alarm when RAIM is unavailable for the phase of flight.

Navigation log discipline: note waypoint ETA, fuel remaining and minimum safe altitude, and cross-check the map, ground features, GNSS and radio aids rather than relying on one source.

Pre-flight: licences and medical, NOTAM, weather, mass and balance, performance, fuel, aircraft documents and technical log, plus a walk-around covering fuel, oil, tyres, brakes, control surfaces and lights.

Before take-off: controls free and correct, instruments set (QNH, heading, altitude), fuel and power checks, magnetos, carburettor heat, transponder, lights, doors and cabin secure.

Engine failure after take-off: establish the glide at VY (or VX to clear an obstacle), select a landing area ahead, avoid turning back below about 500 ft, run the restart drills if time allows, brief the cabin and transmit MAYDAY.

Emergency descent: oxygen masks on, squawk 7700, turn 90° off the airway, idle thrust, speedbrakes, descend at VMO/MMO to FL100 or the minimum safe altitude, and notify ATC and the cabin crew.

Wake turbulence: stay at or above the preceding aircraft's flight path, land beyond its touchdown point and accept the ATC time separation; vortices sink and decay but persist longest in calm air.

ELT: 406 MHz transmits a digital identification to Cospas-Sarsat and 121.5 MHz provides homing; confirm the ELT is armed before take-off and check it has not been triggered after a hard landing.

Refuelling: bonding and grounding, no smoking, radios off, fire extinguisher ready, correct grade confirmed and water/sediment drained; passengers on board only under the approved procedure.

Clearances: read back runway, hold-short instruction, altitude, heading, speed, frequency, squawk and altimeter setting; query any clearance that cannot be complied with rather than accepting it.

Ground icing: remove frost, snow and ice from wings, tail and control surfaces and apply de-icing/anti-icing fluid within its holdover time before take-off.

Lift = CL × ½ ρ V² S. Lift rises with the square of speed, so the coefficient of lift required falls as speed increases.

A stall occurs at the critical angle of attack, not at a fixed speed; the stall speed rises with mass (by √n), load factor and altitude for a given IAS-to-TAS relationship.

Load factor in a level coordinated turn: n = L/W = 1/cos(bank); 30° gives 1.15, 45° gives 1.41, 60° gives 2.0. Stall speed increases by √n, so 41% at 60° bank.

Drag: parasite drag increases with V², induced drag decreases as speed rises; total drag is minimum at L/D max, which is also the best glide and maximum range speed.

Stability: longitudinal static stability requires the CG ahead of the neutral point; dihedral provides lateral stability (sideslip produces roll away from the slip); the fin gives directional stability.

Mach effects: local airflow can reach Mach 1 while the aircraft is below Mach 1 - the critical Mach number. Shock-induced separation gives buffet, Mach tuck and control reversal; sweep raises the critical Mach number.

Flaps increase CL max and drag, lowering the stall and approach speeds, but also reduce the go-around climb gradient while extended.

Adverse yaw: the descending aileron produces more induced drag, yawing the aircraft away from the intended turn; it is countered with coordinated rudder into the turn.

Ground effect: within about one wingspan of the surface, induced drag and downwash reduce, so the aircraft floats and may lift off or land at lower power; climb performance drops abruptly on leaving ground effect.

Distress: MAYDAY spoken three times on the frequency in use or 121.5 MHz; urgency: PAN PAN three times. Both are followed by callsign, position, nature of the problem, intentions and endurance.

Transponder codes: 7700 emergency, 7600 radio failure, 7500 unlawful interference, 2000 when no discrete code is assigned in many regions; mode C or S transmits pressure altitude.

Items that must be read back: route and en-route clearances, altitude/flight level, headings, speeds, frequencies, squawk, altimeter setting, runway and hold-short instructions (read back in full).

Phonetic alphabet: Alfa, Bravo, Charlie…; numbers are spoken digit by digit and 'decimal' is used for frequencies; 'niner' avoids confusion with the German 'nein'.

Loss of radio communication: squawk 7600, try other frequencies and 121.5 MHz, then comply with the published lost-communication procedure or, in VFR, continue and land at the nearest suitable aerodrome.

Readability is reported on a scale of 1 to 5; 'READABILITY 5' means perfectly readable. Make a short test transmission when switching to a new frequency.

Position reports contain callsign, position and time, altitude or flight level, next position and ETA; in the circuit report downwind, base and final as required by the aerodrome procedure.

A VFR flight plan is filed with ATS before departure with route, level, endurance and persons on board, then activated on departure and closed on arrival to prevent unnecessary search and rescue action.