Aviation glossary

Aerodrome Flight Information Service — an information service at uncontrolled aerodromes. Provides traffic, weather and runway information but never issues control clearances.

Above Ground Level — height above the terrain directly beneath the aircraft. Used for VFR minima and obstacle clearance.

Aeronautical Information Publication — the official state reference for airspace, aerodromes, routes and procedures.

Aeronautical Information Regulation and Control — a fixed 28-day cycle used worldwide to publish aeronautical changes simultaneously.

Above Mean Sea Level — altitude referenced to mean sea level. The standard reference in charts and in controlled airspace.

Air Traffic Control — the service that issues clearances and instructions in controlled airspace and is responsible for aircraft separation.

Actual Time of Departure — the exact time an aircraft became airborne (wheels off, or lift-off for helicopters).

Automatic Terminal Information Service — a recorded, continuously repeated broadcast with current weather and operational information at an aerodrome.

Airline Transport Pilot Licence (Helicopter) — the highest helicopter pilot licence. Allows acting as pilot-in-command in multi-pilot commercial operations.

Aerodrome Traffic Zone — the airspace around an uncontrolled aerodrome. Entry requires two-way radio and knowledge of local procedures.

A flight condition in which airflow through the rotor keeps it spinning without engine power. Lets a helicopter land safely after a power failure.

Ceiling And Visibility OK — visibility ≥ 10 km, no significant cloud below 5000 ft (or MSA), no significant weather.

The lever to the left of the pilot that changes the pitch of all rotor blades simultaneously. Sets total thrust — climb or descent.

Commercial Pilot Licence (Helicopter) — a professional licence for commercial helicopter operations. Allows flying for hire and reward.

Control Zone — the controlled airspace around a controlled aerodrome. Entry requires an ATC clearance and the appropriate VFR/IFR flight plan.

The primary helicopter control operated by the right hand. Tilts the rotor disc and sets the direction of flight — forward, back or sideways.

European Union Aviation Safety Agency — the EU authority that issues common rules for aircraft, pilots and aviation organisations.

Estimated Elapsed Time — the expected flight time from take-off to a specified point or destination. Filed in the flight plan.

Estimated Time of Arrival — the expected time of landing or of passing over a specific point.

Estimated Time of Departure — the expected time of take-off.

A tail rotor housed inside the vertical fin. Reduces noise and the risk of tail-rotor strike compared with an exposed rotor.

Flight Information Region — a defined airspace within which flight information and alerting services are provided.

A rotorcraft whose rotor turns freely from the airflow (autorotation) throughout the flight. Thrust is provided by a separate propeller.

Continuous 24-hour service. Used in the AIP to indicate a facility (aerodrome, frequency, fuel) that is available around the clock.

A rotorcraft whose engine-driven main rotor produces both lift and thrust. Can hover, fly in any direction and land almost anywhere.

Helicopter Emergency Medical Service. Helicopters staffed with a physician and paramedic for urgent medical missions.

Indicated Air Speed — the airspeed read directly from the airspeed indicator. Not corrected for altitude, temperature or instrument error.

International Civil Aviation Organization — a UN agency based in Montreal that issues international civil aviation standards.

Instrument Flight Rules — the pilot navigates by radio-navigation instruments independently of outside visibility.

Instrument Meteorological Conditions — weather that does not meet VMC. Flight is only possible under IFR with the appropriate rating.

Marginal visual meteorological conditions — weather that still meets VFR minima, but with very little margin. Demands heightened attention and an escape plan.

A hazardous condition on helicopters with a two-bladed semi-rigid rotor: the rotor hub strikes the mast — usually at low or negative G. Almost always catastrophic.

Minimum Equipment List — the list of equipment that may be inoperative while still allowing the aircraft to operate. Prepared by the operator and approved by the authority.

Meteorological Aerodrome Report — the routine weather report from an aerodrome. Issued every half hour (in the Czech Republic at HH+00 and HH+30).

Minimum Sector Altitude — the lowest altitude within a 25 NM sector around an aerodrome (or nav fix) that provides 1000 ft obstacle clearance (2000 ft in mountains).

A temporary authorisation to fly an aircraft that does not have a valid Certificate of Airworthiness — for post-maintenance test flights, ferry flights to maintenance or experimental operations. Issued by the CAA / EASA.

A reciprocating internal-combustion engine — in helicopters typically an air-cooled flat four or six. Powers the Robinson R22, R44 and Guimbal Cabri G2.

Private Pilot Licence (Helicopter) — a private helicopter pilot licence. Allows non-commercial flying and carrying passengers without payment.

The popular VFR planning and navigation app. Supports flight plans, AIP charts, weather, NOTAMs and live moving-map navigation on a tablet.

A VFR flight cleared by ATC to operate within a control zone in conditions below the standard VMC minima. The pilot is responsible for obstacle clearance.

Visual Flight Rules — the pilot navigates by outside visual reference and must meet VMC minima.

A publication for VFR pilots. Contains aerodrome charts, procedures and frequencies in a more accessible form than the AIP.

Very High Frequency — the 30–300 MHz band. Aviation uses 118–137 MHz for radio communications.

Very Important Person — in aviation, a flight carrying a prominent passenger, usually with stricter requirements on comfort, safety and discretion.

Visual Meteorological Conditions — the visibility and cloud-clearance minima that must be met for a VFR flight.

VHF Omnidirectional Range — a ground-based radio-navigation aid. The airborne receiver derives a radial to or from the station.

A dangerous helicopter aerodynamic condition (VRS). The rotor recirculates its own downwash and loses thrust — adding collective makes it worse.