Iran CAO ATCO Theory cheat sheet

ICAO Convention (Chicago, 1944) Annex 1 = Personnel Licensing; Annex 2 = Rules of the Air; Annex 11 = Air Traffic Services; Annex 14 = Aerodromes.

ICAO Standards are mandatory (differences must be filed under Article 38); Recommended Practices are desirable but not binding.

Iran is an ICAO Contracting State; national rules are issued by CAO Iran and must not fall below Annex standards.

A clearance is an authorisation for an aircraft to proceed under conditions specified by an ATC unit; it does not relieve the pilot-in-command of responsibility for safety of flight.

Controlled airspace is divided into Classes A–G; Class A = IFR only, Class C = IFR and VFR with VFR separated from IFR, Class G = uncontrolled.

Aircraft nationality and registration marks are governed by Annex 7; the certificate of airworthiness by Annex 8.

Reduced vertical separation minimum (RVSM) applies between FL290 and FL410 inclusive, with 1,000 ft separation; above FL410 use 2,000 ft.

The 1944 Convention Article 5 (non-scheduled flights) and Article 6 (scheduled air services require special permission) govern overflight and traffic rights.

Separation minima: radar 5 NM (3 NM within designated TMZ/terminal areas where approved); procedural lateral 10 min or 15 NM, vertical 1,000 ft below FL290 and 2,000 ft above.

Wake turbulence categories by MTOW: L (≤7,000 kg), M (7,000–136,000 kg), H (136,000–560,000 kg), J (Super, A380).

Time-based separation for successive departures: 2 minutes if the preceding aircraft is L or M and the following is H/J; 3 minutes otherwise (typical ICAO guidance).

Flow control measures: level capping, speed control, miles-in-trail, and slot allocation; ground delay programmes are coordinated through CFMU-equivalent flow management positions.

Sector capacity is limited by controller workload, radio frequency occupancy, and conflict complexity; capacity declaration must be published for each ATS unit.

ATFM slot compliance: aircraft must be ready at the gate at the calculated take-off time (CTOT) minus 5 minutes; late or early departure may require re-slotting.

Radar identification methods: PSR paint, SSR code, Mode S, and transfer of identification between adjacent units by direct speech or data link.

ISA: sea level 15 °C, 1013.25 hPa, lapse rate 1.98 °C per 1,000 ft up to 36,090 ft (tropopause).

QNH = pressure reduced to sea level; QFE = pressure at aerodrome elevation; QNE = 1013.25 hPa used above transition altitude.

Transition altitude in Iran is typically 12,000 ft (varies by aerodrome); transition level is the lowest usable FL above TA.

Thunderstorm lifecycle: cumulus (updrafts), mature (updrafts and downdrafts, hail, lightning), dissipating (downdrafts).

Wind shear on final approach is reported as a microburst or gust front; go-around is mandatory if the approach becomes unstable below 1,000 ft AGL.

METAR is the routine aerodrome report (typically half-hourly); SPECI is issued when significant changes occur.

TAF validity is typically 9, 24, or 30 hours; TEMPO and BECMG groups describe temporary and gradual changes.

Volcanic ash (SIGMET) and tropical cyclone advisories are issued as SIGMET; ash can cause engine flameout and windscreen opacity.

Great circle is the shortest path between two points on the sphere; rhumb line maintains constant track but is longer.

Magnetic variation east is subtracted from true to obtain magnetic; deviation is aircraft-specific and applies after variation.

VOR radials are magnetic; a TO indication means the selected course takes the aircraft toward the station.

ILS categories: CAT I 200 ft DH / 550 m RVR; CAT II 100 ft / 300 m; CAT IIIA 50 ft / 200 m; CAT IIIB 0 ft / 50–200 m.

RNAV (GNSS) approaches use lateral navigation only unless LPV or RNP AR is specified; RNP AR requires special crew and aircraft approval.

GNSS position error is influenced by DOP, ionospheric delay, and multipath; RAIM must be available for the approach if required.

Mach number and TAS relationship: TAS = Mach × local speed of sound; speed of sound ≈ 661 kt at sea level ISA, decreasing with temperature.

Lift = ½ ρ V² S CL; induced drag decreases with speed, parasite drag increases with V².

Critical angle of attack is the angle at which the wing stalls; it is independent of weight, bank angle, and density altitude.

Load factor n = L/W; in a level 60° bank, n = 2, so stall speed increases by √2 (≈41%).

Turbofan engines produce maximum thrust at low altitude and high density; thrust decreases with altitude and temperature.

Pressurisation: cabin altitude is normally maintained below 8,000 ft; a rapid decompression requires oxygen masks and emergency descent.

Landing gear and flap extension speeds (VLO, VLE, VFE) are limiting speeds; exceeding them may cause structural damage.

Aircraft categories by approach speed: A <91 kt, B 91–120, C 121–140, D 141–165, E 166–210 kt (Vat).

SHELL model: Software, Hardware, Environment, Liveware; mismatch at interfaces is the source of most errors.

Hypoxia symptoms: euphoria, impaired judgement, cyanosis, and loss of consciousness; time of useful consciousness at FL350 is about 30–60 seconds.

Fatigue risk is highest on the early morning and late night shifts; controlled rest on the flight deck is permitted in some states under strict conditions.

Crew resource management (CRM) targets communication, leadership, situational awareness, decision-making, and workload management.

Spatial disorientation is most common during night or IMC flight without visual references; rely on instruments, not sensations.

Stress and arousal follow the Yerkes–Dodson curve; moderate arousal optimises performance, high arousal degrades it.

Hearing protection and noise exposure: 85 dB over 8 hours is the typical occupational limit; aircraft noise can exceed 100 dB near engines.

Readback is required for clearances, runway assignments, hold-short instructions, altimeter settings, and frequency changes.

The phonetic alphabet: Alpha, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu.

Numbers are spoken digit by digit except FLs (e.g., FL350 = 'flight level three five zero') and headings ('heading zero nine zero').

Emergency frequencies: 121.5 MHz (VHF), 243.0 MHz (UHF military), 406 MHz (ELT).

'MAYDAY' is the distress call; 'PAN PAN' is the urgency call; neither is used for routine communication.

Lost communication: squawk 7600; unlawful interference: squawk 7500; radio failure: squawk 7600; general emergency: squawk 7700.

Frequency change instructions include the new frequency and, when applicable, the next control unit; read back the full frequency.

Primary surveillance radar (PSR) provides position by skin return; secondary surveillance radar (SSR) relies on transponder replies.

Mode A = identity (squawk); Mode C = altitude; Mode S = unique 24-bit address plus data link capability.

ADS-B Out broadcasts position, velocity, and identity; ADS-B In receives traffic and weather.

Multilateration (MLAT) computes position from time difference of arrival at multiple receivers; useful for surface and terminal areas.

A-SMGCS provides surface movement surveillance and routing guidance; it integrates MLAT and SMR data.

CPDLC replaces voice for routine clearances; it is part of the FANS and ATN data link systems.

ILS localiser provides lateral guidance (108–112 MHz); glideslope provides vertical guidance (329–335 MHz).

Radar separation requires identified targets and a minimum separation of 5 NM (or 3 NM where approved).

Emergency phases: uncertainty (INCERFA), alert (ALERFA), distress (DETRESFA); declared by the ATS unit responsible.

On receiving a MAYDAY, the controller must acknowledge, obtain position, altitude, fuel, persons on board, and nature of emergency, then alert SAR.

Aircraft in emergency have priority over all other traffic; the controller should provide separation and clear airspace as required.

Go-around procedure: apply power, pitch for climb, retract gear and flaps per SOP, and report to ATC.

Runway incursion prevention: hold-short instructions must be read back; never cross an active runway without explicit clearance.

Bomb threat or hijack: squawk 7500, follow company SOP, and expect ATC to provide priority and escort.

Bird strike on take-off: if unable to climb, land straight ahead; if airborne, assess engine parameters and return if required.

Standard phraseology is mandatory for routine communication; plain language is used only when phraseology is inadequate.

'Cleared for take-off' is issued only by the aerodrome controller; 'line up and wait' is used when take-off clearance cannot be issued.

'Standby' means wait and the controller will call back; it is not a clearance.

'Say again' requests repetition; 'confirm' requests verification of an instruction or information.

'Wilco' means 'I understand your message and will comply'; 'roger' means 'I have received your message'.

'Affirm' and 'negative' replace 'yes' and 'no' in radio telephony.

Position reports include aircraft identification, position, time, altitude, and next position with ETA.

'Unable' is used when an instruction cannot be complied with; the reason should be stated if time permits.