GCAA Ghana ATPL Theory cheat sheet

ICAO Annex 2 (Rules of the Air) applies over the high seas and, unless States file differences, over contracting States; national AIP differences must be checked before flight.

VMC minima in Class C airspace below 3 050 m (10 000 ft) AMSL: 5 km flight visibility, 1 500 m horizontal and 300 m (1 000 ft) vertical distance from cloud; at and above 3 050 m: 8 km, 1 500 m, 300 m.

Class A: IFR only, all aircraft separated. Class B: IFR and VFR, all separated. Class C: IFR separated from all, VFR separated from IFR only. Class D: IFR separated from IFR, traffic information to VFR. Class E: IFR separated from IFR only. Class F: advisory. Class G: no separation.

Squawk codes: 7500 unlawful interference, 7600 radio failure, 7700 general emergency. Radio failure in VMC: continue VMC, land at nearest suitable aerodrome and report arrival.

Cruising level semicircular rule (magnetic track): 000-179 use odd thousands (or FL) for IFR, 180-359 use even; VFR adds 500 ft. In the Ghana/ECARs region, table applies as published in AIP.

Position reporting: at compulsory reporting points, state callsign, position, time, altitude/level, next position and ETA; ADS-B or CPDLC may substitute where prescribed.

Aerodrome traffic circuit: join downwind at circuit height, left-hand unless published right-hand; give way to aircraft on final and to landing traffic; overtake on the outside.

Runway holding position markings: two solid + two broken yellow bars mark the CAT I/II/III holding point; a single solid + two broken marks the runway holding position; stop before the solid lines.

Wake turbulence separation (time, departure behind heavier): Heavy behind Heavy 2 min, Medium behind Heavy 2 min, Light behind Heavy 3 min; intersection departures add 1 min.

Hydraulic system colour coding (typical): red = port/No.1 system, blue = starboard/No.2, green = No.3 or auxiliary; do not assume across types - consult the AMM.

Pascal's law: pressure applied to an enclosed fluid is transmitted undiminished; force = pressure x area, so a larger piston area gives greater force but shorter stroke.

Bleed-air sources: engine HP/LP compressor, APU load compressor, ground cart. Typical uses: air conditioning/pressurisation, engine and wing anti-ice, cross-bleed engine start, hydraulic reservoir pressurisation.

Cabin pressurisation: outflow valve controls cabin altitude; max differential pressure limits structural stress; cabin rate of change normally limited to about 500 ft/min climb, 300 ft/min descent.

Electrical: AC generators are paralleled only if voltage, frequency and phase are matched; a generator control unit (GCU) trips on over/under-voltage, under-frequency and over-excitation.

DC bus tie logic: essential/emergency buses fed from battery via static inverter or transformer-rectifier units; battery capacity is rated in ampere-hours and discharge rate matters (Peukert effect).

Fire detection: engine loops typically use thermocouple or pneumatic (Lindberg) detectors; a dual-loop system with 'A' and 'B' loops allows a FAULT in one loop while retaining detection.

Emergency equipment: portable oxygen bottles minimum per regulation (e.g. 2 x 311 L for pressurised aeroplanes above 25 000 ft), first-aid kits, fire extinguishers (Halon 1211/1301 or equivalent), ELT 406 MHz, life jackets when over water beyond gliding distance.

Landing gear: oleo strut gas charge is nitrogen (not oxygen - oil fire risk); torque links maintain wheel alignment; anti-skid compares wheel speed to aircraft reference speed.

Pitot-static: total pressure in pitot, static pressure at static ports. Blocked pitot with open static: airspeed reads as altimeter (climbs = increasing IAS). Blocked static with open pitot: IAS over-reads in climb, under-reads in descent; VSI frozen at zero.

Altimeter errors: position error, instrument error, temperature error (cold air - 'high to low, look out below' - true altitude lower than indicated), and barometric setting error.

Machmeter uses pitot-static plus a temperature-compensated mechanism; MMO exceedance indicated by barber pole on the airspeed indicator.

Gyroscopes: rigidity in space (attitude indicator, heading indicator) and precession (rate gyro for turn coordinator). Vacuum-driven gyros spin at about 18 000 rpm; electrical gyros use AC or DC motors.

Turn coordinator shows rate of turn and roll rate; a standard rate turn is 3 degrees per second, i.e. 360 degrees in 2 minutes. Rate-one turn formula: TAS/10 + 7 = bank angle (approx).

ILS indicators: localiser deviation 0.5 degrees full scale, glideslope 0.35 degrees full scale; fly toward the needle. Marker beacons: blue outer (about 4 NM), amber middle (about 3 500 ft from threshold), white inner.

EFIS: EADI/EHSI display attitude, flight director, ILS, weather radar and TCAS; colour conventions - red = warning, amber = caution, green = normal/engaged, white = status.

Radio altimeter operates 0-2 500 ft using frequency modulation continuous wave (FMCW); used for CAT II/III minima and GPWS/EGPWS callouts.

TCAS II: TA (amber circle) and RA (red square). RA must be followed within 5 seconds; 'CLIMB'/'DESCEND' commands are complementary between coordinated aircraft.

Definitions: Basic Empty Mass = empty mass + unusable fuel + full oil + fixed equipment; Dry Operating Mass = BEM + crew + catering + potable water; Take-off Mass = DOM + traffic load + fuel.

Moment = mass x arm (distance from datum). Centre of gravity = total moment / total mass. CG position is normally expressed as % MAC.

CG shift formula: shift = (mass moved x distance moved) / total mass. Moving mass aft moves CG aft; adding mass ahead of CG moves CG forward.

Maximum zero-fuel mass (MZFM) protects wing bending and floor loading; maximum landing mass may be exceeded in emergency but must be checked against performance.

Floor loading limits: maximum running load (kg/m or lb/ft) and maximum load per unit area must not be exceeded; heavy items spread over larger area.

Fuel: SG = mass / volume; 1 kg Jet A-1 is about 1.25 L; 1 US gallon Jet A-1 is about 6.7 lb (3.0 kg); 1 imperial gallon about 8 lb (3.6 kg).

Load sheet checks: ZFM <= MZFM, TOM <= MTOM, LM <= MLM, CG within forward and aft limits for take-off, in-flight (fuel burn) and landing.

Index method: index = (mass x (arm - reference arm)) / constant; used to keep numbers small. Sign conventions must match the load sheet.

Dangerous goods: load compatibility, segregation and securing per ICAO TI; DG mass included in traffic load and affects CG.

Take-off distance available (TODA) = TORA + clearway; take-off run available (TORA) = runway length; ASDA = TORA + stopway.

Balanced field length: the distance at which accelerate-stop distance equals accelerate-go distance; V1 is chosen so that both are minimised.

V speeds: V1 decision speed, VR rotation, V2 take-off safety speed (>= 1.13 VS1 in config), VMCG ground minimum control, VMCA air minimum control, VMO/MMO max operating, VLE/VLO gear, VFE flap.

Climb gradients (CS-25/FAR 25 twin-engine): second segment 2.4%, final take-off 1.2%, approach 2.1%, landing 3.0% (all engines) or 2.7% for two-engine; landing climb 3.2% (some types).

Density altitude = pressure altitude + 120 x (OAT - ISA temp at that level). High density altitude reduces power and increases take-off and landing distances.

Wind effect: headwind decreases ground roll and increases climb gradient; tailwind increases both. Use the greater of headwind/tailwind components as published.

Contaminated runway: use the appropriate braking action and factored distances; wet runway increases landing distance by 15% (or as published).

Obstacle clearance: net take-off flight path must clear all obstacles by 35 ft vertically (or as prescribed), with the net path being gross gradient minus 0.9% (two-engine) or 0.8% (three-engine).

Landing distance required must not exceed LDA; dispatch requires landing distance at destination and alternate not exceeding 60% of LDA on a dry runway (or as operator approved).

Fuel plan: taxi fuel + trip fuel + contingency (typically 5% of trip) + alternate fuel + final reserve (30 min holding at 1 500 ft) + additional/extra fuel.

PIC must ensure fuel on board is sufficient; in-flight replanning requires recalculating fuel to destination and alternate with reserves intact.

True airspeed from IAS: TAS = IAS x (1 + 0.02 x (altitude in thousands)) for a rough estimate; more accurately TAS = IAS x sqrt(rho0/rho).

Mach number: M = TAS / LSS, where LSS = 38.94 x sqrt(T) knots (T in Kelvin); ISA sea level LSS is about 661 kt.

Wind triangle: use the CR-3 or E6B; drift = arcsin((W/V) x sin(WA)) and ground speed from the cosine rule; heading = track - drift.

Pilot navigation: 1 in 60 rule - 1 NM off track after 60 NM equals 1 degree of track error; closing angle = 60 x (distance off / distance flown).

ISA: sea level 15 C, 1013.25 hPa, lapse rate 1.98 C per 1 000 ft up to 36 090 ft (tropopause -56.5 C).

Pressure altitude = elevation + 30 x (1013 - QNH in hPa) approximately; use the altimeter subscale setting to convert between QNH, QFE and 1013.25.

Flight monitoring: cross-check fuel flow against planned burn at each waypoint; a 5% discrepancy warrants a re-plan and possible diversion.

Hypoxia: symptoms include euphoria, impaired judgement, cyanosis, headache. Time of useful consciousness at FL350 is about 30-60 seconds; at FL250 about 3-5 minutes; at FL180 about 20-30 minutes.

Cabin altitude above 10 000 ft: supplemental oxygen required for crew; above 14 000 ft for passengers; above 25 000 ft, quick-donning masks for one pilot at all times.

Decompression: don oxygen mask first, then assist others; emergency descent to 10 000 ft or MSA, whichever is higher.

Vision: rods for night vision (peripheral, low light), cones for colour and detail (fovea). Dark adaptation takes 30 minutes; avoid bright light and smoking.

Circadian rhythm: body temperature lowest about 04:00-06:00 local; alertness lowest in the early hours and mid-afternoon. Jet lag eastward is generally worse than westward.

Fatigue: cumulative sleep debt impairs performance; controlled rest on the flight deck is a recognised mitigation under operator procedures.

Spatial disorientation: somatogravic illusion (acceleration feels like pitch-up), somatogyral (spin), oculogravic; trust instruments, not sensations.

Stress: Yerkes-Dodson curve - performance peaks at moderate arousal and declines at high or low arousal. Stressors: environmental, physiological, psychological.

Crew resource management: assertiveness, situational awareness, briefing, cross-check, and challenge-and-response. Authority gradient too steep or too flat both degrade safety.

ISA: sea level 15 C, 1013.25 hPa, lapse rate 1.98 C/1 000 ft; tropopause at about 36 090 ft (11 km) with -56.5 C.

QNH is the altimeter setting to read elevation on the ground; QFE gives height above the reference point; 1013.25 hPa is the standard setting for flight levels.

Pressure systems: in the northern hemisphere, air flows anticlockwise around a low and clockwise around a high; Buys Ballot's law - with back to wind, low pressure is to the left.

Cloud types: cumulonimbus (CB) gives thunderstorms, icing, turbulence, hail and microbursts; avoid by at least 10 NM and do not fly under the anvil.

Icing: clear (rime) ice forms in stratiform clouds at 0 to -20 C; mixed ice in cumuliform; freezing rain is the most hazardous. Use anti-ice before entering icing conditions.

Thunderstorm life cycle: cumulus, mature, dissipating. The mature stage has both up- and downdrafts, lightning, hail and the most severe turbulence.

Wind shear and microburst: a microburst can produce a 30-50 kt headwind-to-tailwind change over a short distance; escape by applying maximum thrust and pitching to the stick shaker.

Fog: radiation fog forms on clear, calm nights with high humidity; advection fog forms when warm moist air moves over a cold surface; sea fog common off Ghana in the harmattan/coastal season.

Tropical weather in West Africa: ITCZ migration brings the harmattan (dry, dusty, reduced visibility) and the monsoon (moist, convective). Squall lines can produce severe wind shear.

Altimeter: high to low, look out below; cold air makes the altimeter over-read (true altitude lower than indicated).

Earth: oblate spheroid, equatorial radius 6 378 km, polar radius 6 357 km; 1 minute of latitude = 1 NM = 1 852 m.

Great circle: shortest path between two points on a sphere; a rhumb line is a line of constant track (loxodrome). Mercator chart shows rhumb lines as straight lines.

Convergency = change of longitude x sin(latitude); departure (NM) = change of longitude (minutes) x cos(latitude).

1 in 60 rule: track error (degrees) = 60 x distance off track / distance flown; closing angle = 60 x distance off / distance remaining.

Heading = track - drift (wind from the left gives positive drift). Wind correction angle = arcsin((W/V) x sin(WA)).

Magnetic variation: easterly variation is subtracted from true to get magnetic (east is least); deviation is aircraft-specific and read from the compass card.

Time zones: 15 degrees of longitude = 1 hour; UTC is the reference. Local mean time = UTC + longitude/15 (east positive).

Chart scales: 1:500 000 means 1 cm = 5 km; 1:250 000 means 1 cm = 2.5 km. Use the scale bar to measure distances.

Solar and star navigation: the sun crosses the meridian at local noon; Polaris gives northern latitude; the Southern Cross gives southern latitude.

NDB/ADF: needle points to the station; relative bearing + heading = magnetic bearing to station; ADF is affected by thunderstorm and shoreline errors.

VOR: radials are magnetic bearings from the station; TO/FROM flag indicates whether the selected course takes you to or from the station; CDI centred means on the selected radial.

VOR accuracy: line-of-sight, range roughly 1.23 x sqrt(height in feet) NM; errors include scalloping, terrain and cone of confusion overhead.

DME: slant range, not ground distance; accuracy about 0.5 NM or 3% of range. At 6 000 ft over the station, DME reads about 1 NM.

ILS: localiser 108-112 MHz, glideslope 328-336 MHz, markers 75 MHz. Category I DH 200 ft, RVR 550 m; CAT II DH 100 ft, RVR 300 m; CAT III varies.

GPS: needs at least 4 satellites for 3D fix, 5 for RAIM; RAIM requires 24 satellites; WAAS/SBAS improves integrity for approach.

Radar: primary radar uses pulse return time to compute range; secondary radar (SSR) uses transponder codes and altitude (Mode C/S).

RNAV/GNSS: waypoints, legs, fly-by vs fly-over; RNP AR approaches use RF legs and require special crew/aircraft approval.

Transponder: Mode A code, Mode C altitude, Mode S unique address; TCAS coordination uses Mode S.

Take-off briefing: rejected take-off decision (below V1, abort for any significant failure), engine failure after V1, emergency return, terrain, weather, and departure route.

Before take-off: cabin secure, doors armed, flight controls checked, altimeters set (QNH or 1013.25), transponder on, TCAS on, take-off data set.

Approach briefing: type of approach, minima, missed approach, go-around callouts, autopilot/autothrottle use, and the stabilised approach criteria (e.g. 1 000 ft IMC, 500 ft VMC).

Stabilised approach: on speed, on path, on centreline, landing configuration, checklist complete, thrust set by 1 000 ft IMC or 500 ft VMC; otherwise go around.

Emergency: declare MAYDAY or PAN PAN; squawk 7700; give position, level, fuel, persons on board, nature of emergency and intentions.

Fire: engine fire - fire handle, agent discharge, land as soon as possible; cabin fire - smoke hood, extinguisher, land immediately.

Ditching: life jackets on, brace position, doors and overwing exits, life rafts, ELT activation, and survival equipment.

Crew duty limits: flight time, duty period, rest requirements are set by the operator's approved scheme under the State's regulations; record and monitor.

Security: unlawful interference - squawk 7500, follow company procedure, do not transmit sensitive information; use discreet means if able.

Lift = 1/2 x rho x V^2 x S x CL; induced drag = CL^2 / (pi x AR x e) x 1/2 rho V^2 S. Total drag = parasite + induced; L/D max occurs at the speed where they are equal.

Angle of attack is the angle between the chord line and the relative airflow; the critical angle (about 15-16 degrees for many aerofoils) gives CLmax and stall.

Stall speed is proportional to sqrt(weight); a 10% increase in weight raises stall speed by about 5%. Load factor n raises stall speed by sqrt(n).

Load factor: n = 1/cos(bank angle) in a level turn; 60 degrees bank gives n = 2, stall speed increases by 41%.

Bernoulli and Newton: pressure differential plus downwash/momentum change both contribute; the Kutta condition and circulation explain lift generation.

Boundary layer: laminar then turbulent; transition depends on Reynolds number; vortex generators and turbulators delay separation.

Mach effects: critical Mach number (MCRIT) is where local airflow first reaches M = 1; shock waves form; tuck-under and buffet occur at high Mach.

Sweepback: increases MCRIT, reduces lift at a given AoA, and gives a Dutch roll tendency; yaw damper required on swept-wing aircraft.

Stability: positive static stability means a tendency to return; positive dynamic stability means oscillations damp out. Dihedral gives lateral stability; fin gives directional stability.

Flaps: increase CLmax and drag; leading-edge devices (slats) delay stall; spoilers destroy lift and increase drag; speed brakes increase drag.