The legal framework and the responsible authorities
Written fromR.K. Bali, Air Regulations ch 1, with the CAE Oxford Air Law manual for depth, DGCA scope only
Air law works as a hierarchy. International agreement supplies the common framework, India gives that framework domestic legal force, and specialist authorities administer safety, security, investigation, infrastructure and radio spectrum.
From Chicago to an operating requirement
The Convention on International Civil Aviation was signed at Chicago on 7 December 1944. India ratified it. The Convention contains 96 Articles, including Article 1, which recognises complete and exclusive State sovereignty over the airspace above its territory, and Article 2, which treats land areas and adjacent territorial waters as territory.
The Convention created the international system for civil aviation. Its Annexes contain Standards and Recommended Practices. A Standard is intended for uniform application where compliance is recognised as necessary for safety or regularity. A Recommended Practice is desirable for safety, regularity or efficiency. A State remains sovereign and implements international material through its own legal system. If its practice differs from an international Standard, the difference is notified through the prescribed process.
The hierarchy used in India
| Layer | What it does | Exam use |
|---|---|---|
| Chicago Convention | Creates the international legal basis and the organisation for international civil aviation. | Start with sovereignty, territory and State obligations. |
| ICAO Annexes | Set international Standards and Recommended Practices by subject, such as personnel licensing, rules of the air, operations, aerodromes and investigation. | An Annex states the agreed international requirement, but it is not by itself a pilot's domestic operating permission. |
| PANS documents | Give detailed procedures supporting the Annexes. PANS-ATM is Doc 4444 and PANS-OPS is Doc 8168. | Use these for detailed ATS and instrument procedure methods. |
| Bharatiya Vayuyan Adhiniyam 2024 | Provides the principal Indian statutory authority for regulating civil aviation and replaced the Aircraft Act 1934. | It is the primary national legislation in the current DGCA frame. |
| Aircraft Rules 1937 | Provide detailed rules on registration, airworthiness, licensing, operations and related administration. | The Rules turn broad statutory power into enforceable requirements. |
| Civil Aviation Requirements | Publish detailed technical and administrative requirements issued by the Directorate General of Civil Aviation. | Use the applicable Section, Series and Part for the operational detail. |
Interactive From international agreement to cockpit rule
Selected layerChicago Convention
FunctionInternational legal foundation
Who does what in India
| Authority | Core responsibility | Do not confuse it with |
|---|---|---|
| DGCA | Civil aviation safety regulation, including licensing, airworthiness, operations and safety oversight. | Security screening or accident investigation. |
| BCAS | Civil aviation security policy, standards and oversight. | Routine airworthiness certification. |
| AAIB | Independent investigation of aircraft accidents and serious incidents, with safety prevention as the purpose. | Assigning criminal or civil blame. |
| AAI | Airport infrastructure and air navigation services within its assigned functions. | Issuing flight crew licences. |
| WPC Wing | National radio spectrum management and wireless licensing within the telecommunications administration. | Air traffic control service. |
The order mattersAn international provision and a national rule can address the same subject. For a DGCA examination, use the Indian requirement where Bali gives one, while understanding the Convention and ICAO material from which it developed.
Aircraft, people and kinds of operation
Written fromR.K. Bali, Air Regulations ch 1, with the CAE Oxford Air Law manual for depth, DGCA scope only
A definition fixes the boundary of a rule. The words aircraft, operator, pilot-in-command and commercial air transport identify what is regulated, who is responsible and what kind of operation is being conducted.
Aircraft and aircraft categories
| Term | Meaning |
|---|---|
| Aircraft | Any machine that can derive support in the atmosphere from reactions of the air other than reactions of the air against the Earth's surface. |
| Aeroplane | A power driven, heavier than air aircraft deriving lift chiefly from aerodynamic reactions on surfaces that remain fixed under given conditions of flight. |
| Helicopter | A heavier than air aircraft supported in flight chiefly by reactions of the air on one or more power driven rotors on substantially vertical axes. |
| Glider | A non-power driven, heavier than air aircraft deriving lift chiefly from aerodynamic reactions on fixed surfaces. |
| Airship | A power driven, lighter than air aircraft. |
| Amphibian | An aeroplane capable normally of taking off from and alighting on either land or water. |
| Aircraft category | A classification according to basic characteristics, such as aeroplane, helicopter, glider or free balloon. |
| Type of aircraft | Aircraft of the same basic design, including modifications other than those causing a change in handling or flight characteristics. |
| Large aeroplane | An aeroplane with a maximum certificated take-off mass over 5,700 kg. |
| Small aeroplane | An aeroplane with a maximum certificated take-off mass of 5,700 kg or less. |
| Air-taxiing | Movement of a helicopter or vertical take-off aircraft above the aerodrome surface, normally in ground effect and at a ground speed normally below 37 km/h (20 kt). |
| Microlight aircraft | Bali distinguishes a single-seat fixed-wing microlight not exceeding 330 kg and a two-seat fixed-wing microlight not exceeding 450 kg, each with wing area not less than 10 square metres. |
Responsible people
| Term | Meaning |
|---|---|
| Operator | A person, organisation or enterprise engaged in or offering to engage in an aircraft operation. |
| Pilot-in-command | For commercial operations, the pilot designated by the operator as being in command and charged with safe conduct. For general aviation or helicopter operations, the pilot designated by the operator or owner. |
| Co-pilot | A licensed pilot serving in a piloting capacity other than as pilot-in-command, except a pilot carried solely to receive flight instruction. |
| Flight crew member | A licensed crew member charged with duties essential to aircraft operation during flight time. |
| Crew member | A person assigned by an operator to duty on an aircraft during a flight duty period. |
| Cabin crew member | A crew member who performs duties assigned for passenger safety, but who does not act as a flight crew member. |
| Flight operations officer or dispatcher | A person designated by the operator to assist the pilot-in-command in safe conduct and operational control of a flight under the applicable requirements. |
Classes of operation
| Operation | Defining feature |
|---|---|
| Commercial air transport | An aircraft operation involving transport of passengers, cargo or mail for remuneration or hire. |
| General aviation | An aircraft operation other than commercial air transport or aerial work. |
| Aerial work | An operation in which an aircraft is used for specialised services such as agriculture, construction, photography, surveying, observation, patrol, search and rescue or aerial advertisement. |
| Public transport | Carriage of persons or things for remuneration, and carriage without remuneration when performed by an air transport undertaking as defined by the Rules. |
| Private aircraft | An aircraft other than an aerial work aircraft or public transport aircraft. |
| State aircraft | Military aircraft and aircraft exclusively employed in Government services such as customs, police or posts. |
| Foreign aircraft | An aircraft registered outside India. |
Flight time and operational control
For an aeroplane, flight time runs from the moment it first moves for take-off until it finally comes to rest at the end of the flight. This is commonly called block-to-block or chock-to-chock time. For a helicopter, it runs from rotor start until the rotors stop after flight. Operational control is authority over initiating, continuing, diverting or terminating a flight in the interests of safety, regularity and efficiency.
Responsibility follows the defined roleThe operator organises and controls the operation. The pilot-in-command carries the defined command responsibility for the individual flight.
Vertical references, weather and approach minima
Written fromR.K. Bali, Air Regulations ch 1, with the CAE Oxford Air Law manual for depth, DGCA scope only
Altitude, height and flight level are not interchangeable. Each uses a different reference, and that reference controls how terrain clearance, approach minima and vertical separation are understood.
The vertical words
| Term | Reference and meaning | Related setting |
|---|---|---|
| Elevation | The vertical distance of a point or level on or affixed to the Earth's surface, measured from mean sea level. | Aerodrome elevation is the elevation of the highest point of the landing area. |
| Altitude | The vertical distance of a level, point or object measured from mean sea level. | QNH makes a pressure altimeter indicate altitude. |
| Height | The vertical distance of a level, point or object measured from a specified datum. | QFE makes the altimeter indicate height above the QFE reference datum. |
| Flight level | A surface of constant atmospheric pressure related to 1013.2 hPa and separated from other surfaces by specified pressure intervals. | Set 1013.2 hPa to indicate flight levels. |
| Level | A generic word meaning height, altitude or flight level as the context requires. | Always identify which reference is in use. |
| Pressure altitude | An atmospheric pressure expressed as the altitude corresponding to it in the Standard Atmosphere. | It is pressure based, not a direct geometric measurement. |
| Transition altitude | The altitude at or below which vertical position is controlled by reference to altitudes. | Below it, use the local altimeter setting as required. |
| Transition level | The lowest flight level available for use above the transition altitude. | Above it, use the standard setting. |
| Transition layer | The airspace between transition altitude and transition level. | It prevents mixing altitude and flight level references at the changeover. |
Interactive Which datum is underneath the aircraft?
Selected quantityAltitude
ReferenceMean sea level
Visibility and cloud terms
| Term | Meaning |
|---|---|
| Visibility | For aeronautical purposes, the greater of the distance at which a suitable black object can be seen against a bright background and the distance at which a light of about 1,000 candelas can be seen against an unlit background. |
| Flight visibility | Visibility forward from the cockpit of an aircraft in flight. |
| Ground visibility | Visibility at an aerodrome as reported by an accredited observer. |
| Runway visual range | The range over which a pilot on the runway centre line can see runway surface markings or the lights delineating or identifying the centre line. |
| Ceiling | The height above ground or water of the base of the lowest cloud layer below 6,000 m (20,000 ft) covering more than half the sky. |
| VMC | Meteorological conditions expressed by visibility, distance from cloud and ceiling that are equal to or better than the specified minima. |
| IMC | Meteorological conditions expressed by visibility, distance from cloud and ceiling that are less than the specified VMC minima. |
| Night | The hours between the end of evening civil twilight and the beginning of morning civil twilight, or another period prescribed by the authority. Civil twilight uses the Sun's centre 6 degrees below the horizon. |
Approach minima and obstacle terms
| Term | What it controls | Reference |
|---|---|---|
| DA or DH | The point in a 3D instrument approach at which a missed approach must be initiated if the required visual reference is not established. | Decision altitude is referenced to mean sea level. Decision height is referenced to threshold elevation. |
| MDA or MDH | The minimum altitude or height in a 2D approach or circling approach below which descent must not be made without the required visual reference. | MDA uses mean sea level. MDH uses aerodrome elevation or the applicable threshold elevation. |
| OCA or OCH | The lowest altitude or height used to establish compliance with obstacle clearance criteria. | OCA uses mean sea level. OCH uses the applicable runway or aerodrome reference. |
| MEA | The altitude for an en route segment that provides navigation and communication reception, complies with the airspace structure and provides required obstacle clearance. | En route segment. |
| MOCA | The minimum altitude for a defined segment that provides required obstacle clearance. | Defined route segment. |
| MSA | The lowest altitude providing at least 300 m (1,000 ft) clearance over objects within a 46 km (25 NM) sector centred on a radio navigation aid. | Emergency or orientation reference, not an approach clearance. |
Instrument approach and runway classifications
| Class | Guidance and limiting definition |
|---|---|
| Non-precision approach | A 2D instrument approach operation, Type A, with an operating minimum of 250 ft or above. |
| Approach with vertical guidance | A performance-based navigation procedure designed for a 3D instrument approach operation, Type A. |
| Precision approach | A navigation-system based 3D instrument approach. Type A has an operating minimum of 250 ft or above, while Type B is below 250 ft. |
| Category I runway | Decision height not lower than 60 m (200 ft), with visibility not less than 800 m or RVR not less than 550 m. |
| Category II runway | Decision height lower than 60 m (200 ft) but not lower than 30 m (100 ft), and RVR not less than 300 m. |
| Category III runway | Decision height lower than 30 m (100 ft), or no decision height, and RVR less than 300 m or no RVR limitation. |
Altitude is not heightIf the datum changes, the word changes. An MDA and an MDH may describe the same limiting surface, but their numerical references are different.
Airspace, traffic services and surveillance
Written fromR.K. Bali, Air Regulations ch 1, with the CAE Oxford Air Law manual for depth, DGCA scope only
Airspace definitions tell you where a service exists and what that service can do. They also separate a clearance from advice, information and alerting.
Services and units
| Term | Meaning |
|---|---|
| Air traffic | All aircraft in flight or operating on the manoeuvring area of an aerodrome. |
| Air traffic service | A generic term covering flight information service, alerting service, air traffic advisory service and air traffic control service. |
| Air traffic control service | A service preventing collisions between aircraft and, on the manoeuvring area, between aircraft and obstructions, while expediting and maintaining an orderly traffic flow. |
| ATC clearance | Authorisation for an aircraft to proceed under conditions specified by an ATC unit. |
| Controlled flight | Any flight subject to an ATC clearance. |
| Flight information service | A service giving advice and information useful for safe and efficient conduct of flights. |
| Alerting service | A service notifying appropriate organisations about aircraft needing search and rescue aid and assisting those organisations. |
| Air traffic advisory service | A service within advisory airspace that provides advice intended to make separation as effective as practical. |
| ATC unit | A generic term for an area control centre, approach control unit or aerodrome control tower. |
| ATS reporting office | A unit established to receive reports concerning ATS and flight plans submitted before departure. |
Named volumes of airspace
| Term | Definition |
|---|---|
| Flight information region | Airspace of defined dimensions within which flight information service and alerting service are provided. |
| Control area | Controlled airspace extending upwards from a specified limit above the Earth. |
| Control zone | Controlled airspace extending upwards from the surface to a specified upper limit. |
| Airway | A control area or portion of it established in the form of a corridor. |
| Aerodrome traffic zone | Airspace of defined dimensions established around an aerodrome for protection of aerodrome traffic. |
| ATS route | A specified route designed to channel traffic as necessary for provision of ATS. It can be an airway, advisory route, controlled or uncontrolled route, or an arrival or departure route. |
| Advisory airspace | Airspace of defined dimensions, or a designated route, within which air traffic advisory service is available. |
| Danger area | Airspace of defined dimensions within which activities dangerous to aircraft may exist at specified times. |
| Restricted area | Airspace of defined dimensions over a State's land or territorial waters within which flight is restricted under specified conditions. |
| Prohibited area | Airspace of defined dimensions over a State's land or territorial waters within which flight is prohibited. |
Navigation and surveillance
| Term | Meaning |
|---|---|
| Area navigation | A method permitting aircraft operation on any desired flight path within aid coverage, within self-contained system capability, or by a combination. |
| Heading | The direction in which the longitudinal axis of an aircraft is pointed, usually expressed in degrees from north as true, magnetic, compass or grid. |
| Track | The projection on the Earth's surface of the path of an aircraft, usually expressed in degrees from north as true, magnetic or grid. |
| Significant point | A specified geographical location used to define an ATS route or aircraft flight path and for other navigation and ATS purposes. The three categories are a ground-based navigation aid, an intersection and a waypoint. |
| RNP specification | A navigation specification that includes on-board performance monitoring and alerting, identified by the prefix RNP. |
| RNAV specification | A navigation specification that does not include the requirement for on-board performance monitoring and alerting, identified by the prefix RNAV. |
| ATS surveillance system | A generic expression that can include ADS-B, primary surveillance radar, secondary surveillance radar or a comparable ground system. |
| ADS-B | A means by which aircraft, vehicles and other objects automatically broadcast identification, position and additional data in a broadcast mode. |
| ADS-C | A means by which the terms of an ADS-C agreement are exchanged through data link and reports follow the agreed conditions. |
| ACAS | An aircraft system using transponder signals, independent of ground equipment, to advise the pilot about potentially conflicting equipped aircraft. |
Clearance is specificInformation, advice and alerting support a pilot. An ATC clearance is the defined authorisation to proceed under conditions specified by an ATC unit.
Aerodromes, runway areas and declared distances
Written fromR.K. Bali, Air Regulations ch 1, with the CAE Oxford Air Law manual for depth, DGCA scope only
The surface terms form a nested picture. An apron belongs to the movement area but not the manoeuvring area, while a runway is one defined part of the manoeuvring area.
The aerodrome surface
| Term | Meaning |
|---|---|
| Aerodrome | A defined area on land or water, including buildings, installations and equipment, intended wholly or partly for aircraft arrival, departure and surface movement. |
| Apron | A defined area intended to accommodate aircraft for loading or unloading passengers, mail or cargo, fuelling, parking or maintenance. |
| Manoeuvring area | The part of an aerodrome used for take-off, landing and taxiing, excluding aprons. |
| Movement area | The part used for take-off, landing and taxiing, consisting of the manoeuvring area and apron or aprons. |
| Landing area | The part of a movement area intended for aircraft landing or take-off. |
| Runway | A defined rectangular area on a land aerodrome prepared for aircraft landing and take-off. |
| Taxiway | A defined path on a land aerodrome established for taxiing and linking one part of the aerodrome with another. |
| Runway-holding position | A designated position protecting a runway, obstacle limitation surface or instrument landing critical or sensitive area, where taxiing aircraft and vehicles stop and hold unless authorised. |
| Intermediate holding position | A designated traffic control position at which taxiing aircraft and vehicles stop and hold when instructed. |
| Threshold | The beginning of the portion of the runway usable for landing. |
| Displaced threshold | A threshold not located at the extremity of a runway. |
| Stopway | A rectangular area beyond the take-off run available, prepared so an aircraft can stop after an abandoned take-off. |
| Clearway | A defined rectangular area under the appropriate authority's control, selected or prepared so an aircraft may make part of its initial climb to a specified height. |
| Near-parallel runways | Non-intersecting runways whose extended centre lines converge or diverge by 15 degrees or less. |
| Temporary aerodrome | An aerodrome intended to be used for a period not exceeding six months. |
Interactive Read the aerodrome from outside to inside
HighlightedMovement area
IncludesManoeuvring area and apron
Declared distances
| Distance | Definition |
|---|---|
| TORA | Take-off run available, the runway length declared available and suitable for the ground run of an aeroplane taking off. |
| TODA | Take-off distance available, TORA plus the length of clearway, if provided. |
| ASDA | Accelerate-stop distance available, TORA plus the length of stopway, if provided. |
| LDA | Landing distance available, the runway length declared available and suitable for the ground run of an aeroplane landing. |
Aerodrome use and alternates
| Term | Meaning |
|---|---|
| Aerodrome operating minima | For take-off, limits expressed as RVR or visibility and, if necessary, cloud conditions. For 2D landing, visibility or RVR and MDA or MDH. For 3D landing, visibility or RVR and DA or DH. |
| Alternate aerodrome | An aerodrome to which an aircraft may proceed when continuing to or landing at the intended aerodrome becomes impossible or inadvisable and the alternate is suitable. |
| Take-off alternate | An alternate where the aircraft can land if necessary shortly after take-off when the departure aerodrome cannot be used. |
| En-route alternate | An alternate where an aircraft can land after an abnormal or emergency condition while en route. |
| Destination alternate | An alternate to which the aircraft may proceed when landing at the intended destination becomes impossible or inadvisable. |
| Wet runway | A runway whose surface is covered by visible dampness or water up to and including 3 mm deep within the intended area of use. |
| Dry runway | A runway free of visible moisture and not contaminated within the intended area of use. |
Two common trapsThe manoeuvring area excludes aprons. TODA uses clearway, while ASDA uses stopway.
Plans, information, safety and emergency terms
Written fromR.K. Bali, Air Regulations ch 1, with the CAE Oxford Air Law manual for depth, DGCA scope only
The last group turns intentions and events into formal categories. A filed plan is not yet a current plan, an accident is more than an ordinary incident, and the three emergency phases represent increasing certainty and seriousness.
Flight plans and time terms
| Term | Meaning |
|---|---|
| Flight plan | Specified information provided to ATS units concerning an intended flight or portion of a flight. |
| Filed flight plan | The plan as filed with an ATS unit by the pilot or designated representative, without later changes. |
| Current flight plan | The flight plan, including changes brought about by subsequent clearances. |
| Operational flight plan | The operator's plan for safe conduct of a flight based on performance, operating limitations and expected route and aerodrome conditions. |
| Repetitive flight plan | A plan for a series of frequently recurring, regularly operated flights with identical basic features, submitted for retention and repetitive use. |
| Estimated off-block time | The estimated time at which the aircraft will begin movement associated with departure. |
| Estimated time of arrival | For IFR, the estimated time over the designated point from which an instrument approach is intended, or over the aerodrome if there is no associated aid. For VFR, the estimated time over the aerodrome. |
| Expected approach time | The time at which ATC expects a delayed arriving aircraft to leave the holding fix to complete its approach. Actual departure from the hold depends on approach clearance. |
Aeronautical information
| Term | Purpose |
|---|---|
| AIP | A publication issued by or with State authority containing aeronautical information of a lasting character essential to air navigation. |
| AIC | A notice containing information that does not qualify for a NOTAM or AIP inclusion but concerns flight safety, air navigation, or technical, administrative or legislative matters. |
| NOTAM | A notice distributed by telecommunications containing information about establishment, condition or change in a facility, service, procedure or hazard, timely knowledge of which is essential to flight operations personnel. |
| AIRAC | A system for advance notification, based on common effective dates, of circumstances requiring significant operational changes. |
| Pre-flight information bulletin | A presentation of current NOTAM information of operational significance, prepared before flight. |
Occurrence classification
| Term | Boundary of the definition |
|---|---|
| Accident | An occurrence associated with aircraft operation, from boarding with intent to fly until disembarkation, in which a person is fatally or seriously injured, the aircraft sustains specified substantial damage or structural failure, or the aircraft is missing or completely inaccessible, subject to stated exclusions. |
| Incident | An occurrence other than an accident, associated with aircraft operation, that affects or could affect safe operation. |
| Serious incident | An incident involving circumstances indicating that there was a high probability of an accident. |
| Serious injury | An injury sustained by a person in an accident that meets the specified severity criteria. |
| Safety | A state in which risks associated with aviation activities are reduced and controlled to an acceptable level through a continuing process of hazard identification and risk management. |
| Dangerous goods | Articles or substances capable of posing a hazard to health, safety, property or the environment and listed or classified under the applicable Technical Instructions. |
The three emergency phases
| Phase | Meaning |
|---|---|
| INCERFA, uncertainty phase | Uncertainty exists about the safety of an aircraft and its occupants. |
| ALERFA, alert phase | Apprehension exists about the safety of an aircraft and its occupants. |
| DETRESFA, distress phase | There is reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger and require immediate assistance. |
Documents controlling operation
| Term | Meaning |
|---|---|
| Operations manual | A manual containing procedures, instructions and guidance for operational personnel in carrying out their duties. |
| Operations specifications | The authorisations, conditions and limitations associated with an air operator certificate and subject to the conditions in the operations manual. |
| MMEL | A list established for an aircraft type by the organisation responsible for its type design, with State of Design approval, identifying items permitted to be unserviceable at flight commencement under stated conditions. |
| MEL | An operator-prepared list, approved for a particular operation, that permits operation under specified conditions with particular equipment inoperative and is no less restrictive than the MMEL. |
| Maintenance | Tasks required to ensure continuing airworthiness, including overhaul, inspection, replacement, defect rectification, modification, repair or test. |
States connected with an aircraft
| State | Connection |
|---|---|
| State of Registry | The State on whose register the aircraft is entered. |
| State of the Operator | The State where the operator's principal place of business is located, or permanent residence if there is no principal place of business. |
| State of Design | The State having jurisdiction over the organisation responsible for the type design. |
| State of Manufacture | The State having jurisdiction over the organisation responsible for final aircraft assembly. |
| State of Occurrence | The State in whose territory an accident or incident occurs. |
Read definitions as testsAsk what event, time period, place, person or level of seriousness places the case inside the definition. The qualifying words are usually the examinable part.