ANAC Commercial Pilot Helicopter (PCH) key terms

A mandatory instruction issued by the certifying authority requiring inspection, modification, or replacement of a component within a stated time, binding on all operators of the affected aircraft type.

The Brazilian Civil Aviation Regulation set published by ANAC, structured in numbered parts that mirror ICAO standards and govern certification, operation, licensing, and maintenance of aircraft in Brazil.

An approved document specifying which instruments or equipment may be inoperative at dispatch, together with the operating conditions and repair intervals that apply to each permitted deficiency.

The scope of flying a licence holder may perform for remuneration, including acting as pilot in command of aircraft in the certified category, subject to ratings, recency, and medical validity.

An endorsement on a pilot licence authorising flight of a specific aircraft type that requires type-specific training and testing, typically applied to helicopters above a defined mass or complexity threshold.

An endorsement permitting flight of a group of similar aircraft, such as single-engine piston helicopters, rather than one individual type, granted after appropriate training and skill test.

The document prepared before flight listing route, altitudes, fuel and time calculations, alternates, and mass data, which the pilot in command must accept and sign as the basis for the flight.

A vibration phenomenon in two-blade teetering rotors where the fuselage and rotor interact at a frequency near rotor speed, producing a strong vertical oscillation felt in the cabin during certain airspeed and load conditions.

A self-exciting, potentially destructive oscillation that occurs when the frequency of the helicopter rocking on its landing gear matches the rotor's in-plane motion, rapidly amplifying if not stopped by lifting off or reducing rotor speed.

A hinge that allows each blade to move slightly fore and aft in the plane of rotation, relieving in-plane bending stresses caused by drag changes and by Coriolis effects during flapping.

A hinge permitting the blade to move up and down relative to the hub, allowing the blade to rise on the advancing side and descend on the retreating side so that lift is balanced and dissymmetry of lift is absorbed.

A single central hinge used on two-blade semi-rigid rotors that lets the paired blades see-saw as a unit, balancing lift between the advancing and retreating sides without individual flapping hinges.

A one-way clutch between the engine and the main rotor drive that transmits power to the rotor while allowing the rotor to turn freely if the engine stops, enabling autorotation.

The imbalance of lift between the advancing and retreating halves of the rotor disc caused by their different airspeeds, corrected by blade flapping and cyclic feathering so the disc tilts without producing roll.

The extra lift and reduced power required once airflow through the rotor becomes horizontal rather than vertical, occurring from about ten to fifteen knots of airspeed and improving tail rotor efficiency too.

The airspeed, roughly fifteen to twenty knots, at which the rotor becomes fully efficient in forward flight, the induced flow through the disc is minimised, and the helicopter climbs or accelerates noticeably.

The downward velocity imparted to air as it is drawn through the rotor system, producing induced drag and requiring power; it is greatest in the hover and decreases as forward airspeed rises.

Loss of lift on the retreating blade at high airspeed or high load when its airspeed falls so low that the required angle of attack exceeds the stall angle, producing vibration, pitch-up, and roll.

A condition in which the helicopter descends into its own downwash at low airspeed and high power, requiring a large power increase to arrest, recognised by high sink rate, low airspeed, and excessive power demand.

A hazardous descent condition at low airspeed where recirculating vortices form around the rotor, causing turbulence, loss of control effectiveness, and a rapid sink rate that recovery requires forward or lateral movement to escape.

An unpowered flight state in which upward airflow through the rotor drives the blades and produces lift, allowing a controlled descent and landing after engine failure or drive failure.

The landing technique after an engine failure, using a flare to trade forward speed and rotor inertia for a cushioned touchdown, followed by collective application to absorb remaining energy.

A chart showing combinations of height and airspeed from which a safe autorotative landing cannot be assured, so pilots avoid hovering or low-speed flight inside the shaded region.

The maximum density altitude at which the helicopter can hover, either in ground effect or out of ground effect, at a given mass and power setting, published in the performance section of the flight manual.

Pressure altitude corrected for non-standard temperature, indicating the air density the helicopter actually experiences; high values reduce lift, engine power, and tail rotor authority.

The altitude indicated when the altimeter subscale is set to the standard datum of 1013.2 hPa, used as the basis for performance charts and flight levels above the transition altitude.

The forward and aft boundaries within which the loaded helicopter's centre of gravity must lie, ensuring controllability, adequate cyclic range, and acceptable handling in all phases of flight.

The mass of the helicopter as delivered plus fixed equipment, unusable fuel, and full operating fluids, forming the starting point for every weight and balance computation.

The difference between maximum certificated mass and basic empty mass, representing the total mass available for crew, passengers, baggage, and usable fuel.

The quantity of fuel that must remain at destination or alternate, usually expressed as a period of flight time at holding or cruise consumption, and never planned for use except in contingency.

The calculation of fuel required for taxi, trip, contingency, alternate, final reserve, and any extra, verified against consumption figures and amended in flight as actual burn becomes known.

A false perception of position, attitude, or motion relative to the earth, arising when visual cues are lost and the pilot misinterprets vestibular sensations, most dangerous at night or in cloud.

The inner-ear organs, semicircular canals and otoliths, that sense rotation and linear acceleration; they cannot distinguish sustained acceleration from gravity, producing illusions in the absence of visual reference.

A false sensation of pitching up during acceleration or pitching down during deceleration, caused by otolith stimulation, which can lead a pilot to push or pull the controls in the wrong direction.

A deficiency of oxygen reaching body tissues, producing judgement errors, euphoria, and impaired vision at altitude; helicopters flying high without pressurisation require oxygen above specified cabin altitudes.

Excessive breathing rate that lowers blood carbon dioxide, causing dizziness, tingling, and faintness whose symptoms resemble hypoxia, and which is treated by slowing the breathing rate.

The altitude at or below which the altimeter is set to local pressure and above which the standard setting is used, marking the change between altitude and flight level in the altimeter setting procedure.

The altimeter subscale setting that, when applied at aerodrome level, makes the instrument indicate the aerodrome elevation above mean sea level, derived from the local pressure reduced to sea level.

The altimeter subscale setting that makes the instrument read zero at the aerodrome reference point, so the pilot sees height above the aerodrome rather than altitude above sea level.

An oscillating airflow downstream of a ridge in stable strong winds, marked by lenticular cloud and violent up- and downdrafts that can exceed a helicopter's climb capability and cause severe turbulence.

A change of wind speed or direction over a short distance or time, often near fronts, thunderstorms, or buildings, which can abruptly alter airspeed and lift during takeoff, approach, or hover.

The minimum flight visibility and distance from cloud that must be maintained for visual flight in a given airspace class, below which an instrument clearance or special approval is required.

An authorisation allowing flight in controlled airspace with reduced visibility below normal VFR minima, subject to clearance and, for helicopters, often with lower limits than for fixed-wing aircraft.

The repetition by the pilot of a clearance or instruction to confirm it was received and understood, mandatory for route, level, and frequency instructions and safety-critical items.

The ICAO spelling alphabet, Alfa through Zulu, used to spell out registration letters, waypoints, and unclear words so that each character is unambiguous over the radio.

The four-digit code entered in the transponder that identifies the aircraft to air traffic services, selected as directed by ATC or as prescribed for a defined contingency.

The ATC position or frequency that issues the initial route, level, and transponder clearance before departure, which the pilot copies, reads back, and confirms as correct.