Ultra-light Aeroplane (ULTRA) cheat sheet

Ultra-light definitions vary by state: most authorities cap empty (or maximum) mass near 300 kg single-seat and around 450-600 kg two-seat, with a low stall speed (commonly 45-65 km/h or 25-35 kt calibrated). Verify the exact national figure before every flight.

Registration and airworthiness: an ultra-light normally needs a nationality/registration mark and a valid permit or certificate of airworthiness; the permit is usually time-limited and tied to a maintenance schedule.

Pilot licensing: most states require a specific ultra-light licence or an endorsement on a recreational permit, with a medical declaration or class 2 medical and a biennial flight review.

Right-of-way rules: converging aircraft of the same category give way to the one on the right; a lower aircraft gives way to a higher one on final approach; power-driven aircraft give way to gliders, balloons and aircraft towing.

VMC minima (typical, below 900 m/3000 ft AMSL): 5 km flight visibility, 1500 m horizontally and 300 m (1000 ft) vertically from cloud; above 900 m: 8 km visibility and 1500 m horizontal separation.

Controlled airspace: an ultra-light normally needs a clearance or a specific exemption to enter classes A-D; transponder and radio carriage requirements depend on the class and the state.

Fuel and documents: carry registration, permit, insurance, pilot licence and medical; minimum fuel is typically 30 minutes for day VFR plus a reserve, more for night or over-water.

Flight plan and reporting: for cross-country flights file a plan or flight note, and close it on arrival; failure to close triggers search-and-rescue action.

Accident/damage reporting: report immediately any accident causing death or serious injury, and any incident affecting airworthiness; keep the wreckage untouched unless needed for rescue.

Standard atmosphere: sea-level pressure 1013.25 hPa, temperature 15 °C, lapse rate 2 °C per 1000 ft up to the tropopause (~36,000 ft).

Pressure altitude = indicated altitude corrected for the local altimeter setting; density altitude = pressure altitude corrected for temperature. High density altitude lengthens takeoff and climb and reduces climb rate.

Rule of thumb: density altitude rises roughly 120 ft per 1 °C above ISA at a given pressure altitude (about 1 % per 2.8 °C), so a hot day at a high field is the worst takeoff case.

Wind: surface friction backs the wind and reduces speed; at 2000 ft AGL wind is typically 20-30° more backed and 30-50 % stronger than the surface report.

Cloud bases: convective cloud base (ft AGL) ≈ (temperature − dewpoint in °C) × 400; a spread of 5 °C gives a base near 2000 ft.

Stability: a decreasing temperature lapse rate or an inversion means stable air, smooth flight, haze and poor visibility; a steep lapse rate means unstable air, thermals, gusts and showers.

Fronts: a cold front brings a narrow band of heavy showers, squall lines and rapid wind shifts; a warm front brings wide, low cloud and steady rain; both have a wind shift and pressure trough at the surface.

Mountain and valley effects: anabatic (upslope) winds by day, katabatic (downslope) winds at night; lee waves and rotors downwind of ridges in strong stable winds.

Icing and carburettor ice: visible moisture and temperatures from 0 to −20 °C favour airframe icing; carburettor ice can form at 0-25 °C with high humidity, signalled by falling RPM and rough running.

True course + wind correction = true heading; true heading ± magnetic variation = magnetic heading; magnetic heading ± deviation = compass heading. East is least (subtract), west is best (add) for variation.

Wind triangle: wind correction angle ≈ (wind speed ÷ true airspeed) × sin(wind angle) × 57.3 degrees; headwind/tailwind component ≈ wind speed × cos(wind angle).

1-in-60 rule: an off-track error of 1 nm after 60 nm flown is a 1° track error; correction to destination = track error × (distance flown ÷ distance remaining).

Time and fuel: time = distance ÷ groundspeed; fuel = time × hourly consumption, plus a fixed reserve. Recompute groundspeed at each waypoint rather than trusting the plan.

Dead reckoning needs heading, time, speed and wind; pilotage confirms position from ground features. Use both, plus a map folded to the next leg and a watch set to a known datum.

GNSS: check RAIM/accuracy before flight, set the datum to WGS-84, and treat the receiver as an aid - keep a chart and a compass heading as the primary cross-check.

Magnetic variation changes with position and time; in some regions it is large enough to dominate the calculation, so read it from the chart rather than from memory.

Altimetry: set QNH to read altitude above mean sea level; set the standard pressure 1013.25 hPa above the transition altitude to fly flight levels. Below the transition level, use QNH.

Lift L = ½ρV²SC_L. Lift rises with the square of speed, so a 10 % speed increase gives about 21 % more lift; a stall occurs at the critical angle of attack, independent of speed, weight and bank.

Load factor in a level turn n = 1 ÷ cos(bank). At 60° bank n = 2, so the stall speed rises by √2 ≈ 1.41 and the aircraft can be stalled at any speed if the angle of attack is exceeded.

Stall speed varies with the square root of the weight: at 1.2 times the weight the stall speed rises by about 10 %.

Induced drag falls with speed while parasite drag rises with V²; total drag is minimum at the speed for best glide, which gives the maximum range in a glide.

Best angle of climb (Vx) gives the greatest height gain per ground distance and is used to clear obstacles; best rate (Vy) gives the greatest height gain per time.

Ground effect: within about one wingspan of the ground, induced drag falls and the aircraft floats; it may lift off below flying speed and then sink when leaving the cushion.

Crosswind: the crosswind component ≈ wind speed × sin(angle between wind and runway); a 20 kt wind at 30° gives about 10 kt of crosswind.

Weight and balance: the centre of gravity must stay within limits. Aft CG reduces stability and pitch authority; forward CG raises stall speed and lengthens the takeoff run.

Engine and pre-takeoff checks: verify fuel quantity and quality, carburettor heat, magnetos, controls free and correct, and a positive rate of climb with the airspeed alive before turning.

Hypoxia: symptoms begin around 10,000 ft in an unacclimatised pilot - euphoria, poor judgement, tingling and blue lips. Above 10,000 ft use supplemental oxygen; above 12,500 ft it is normally required.

Hyperventilation mimics hypoxia; both give dizziness and tingling. Treat by slowing the breathing rate and, if in doubt, descend and use oxygen.

Carbon monoxide from the engine heater causes headache, drowsiness and cherry-red lips; suspect it whenever exhaust fumes are present, shut the heater and open fresh-air vents.

Spatial disorientation: without visual reference, the vestibular system gives false sensations. In cloud or at night, trust the instruments and maintain a standard scan; never fly VFR into IMC.

Decision-making: use a model such as PAVE (Pilot, Aircraft, enVironment, External pressures) before flight and DECIDE (Detect, Estimate, Choose, Identify, Do, Evaluate) in flight.

Fatigue and stress degrade reaction time and judgement; the legal minimum rest is not the same as fitness to fly. Self-assess with IMSAFE (Illness, Medication, Stress, Alcohol, Fatigue, Emotion).

Alcohol: most states enforce a limit well below the driving limit, plus a bottle-to-throttle interval of 8 hours; the body clears alcohol at roughly one standard drink per hour.

Sterile cockpit and checklist discipline: no non-essential activity below 1000 ft AGL; read checklists aloud and use do-verify or read-do consistently, never from memory for critical items.

Emergency priorities: aviate, navigate, communicate. Fly the aircraft first, then fix the position, then transmit a MAYDAY with position, altitude, nature of problem and intentions.