The available take-off run length, plus the stopway length if provided.

A surveillance system in which an aircraft or vehicle equipped with cooperative data link transmitter periodically broadcasts its GPS-derived position and other information, such as velocity, over the data link. This data is received by a ground-based transceiver for processing and display at an air traffic control facility.

ADS-C (Automatic Dependent Surveillance-Contract) is a datalink-based system where aircraft automatically transmit data, like position and intent, to air traffic control (ATC) based on a contract between the ground system and the aircraft, without pilot interaction

A simple method for interrelating the numerous specifications concerning aerodrome characteristics to provide a series of aerodrome facilities suitable for the aeroplanes intended to operate there. The aerodrome reference code—comprising a code number and letter selected for aerodrome planning purposes—holds the meanings assigned to it, as indicated in the table below.

A publication issued by or under the authority of a State, containing aeronautical information of lasting significance essential to air navigation.

A grouping of aircraft based on a Vref speed, if specified, or if not, 1.3 VS0 at the maximum certificated landing weight. Vref, VS0, and the maximum certificated landing weight determine the categories, which are as follows:

A point on the airport designated as the official airport location.

The code word used to designate an alert phase.

An aerodrome to which an aircraft may proceed if it becomes impossible or inadvisable to continue to or land at the intended destination. Alternate aerodromes include:

Take-Off Alternate — An aerodrome where an aircraft can land if necessary shortly after take-off, when returning to the departure aerodrome is not possible.

En Route Alternate — An aerodrome where an aircraft can land after experiencing an abnormal or emergency condition while en route.

Destination Alternate — An alternate aerodrome to which an aircraft may proceed if landing at the intended destination becomes impossible or inadvisable.

ETOPS En Route Alternate — A suitable and appropriate alternate aerodrome where an aeroplane can land after experiencing an engine shutdown or other abnormal or emergency condition while en route in an ETOPS operation.

The atmospheric pressure setting that, when set in the aircraft’s altimeter, causes it to read zero at the airfield’s reference datum.

The constant atmospheric pressure of 29.92 inches of mercury, 1013.25 hectopascals, or 1013.25 millibars, referenced for expressing flight levels.

The atmospheric pressure setting that, when set in the aircraft’s altimeter, causes it to display altitudes referenced to mean sea level.

An approach procedure that prohibits continuation beyond a specific point or height if the reported visibility or RVR is below the specified minimum for that approach.

A navigation method that allows aircraft to operate on any desired flight path within the coverage of station-referenced navigation aids, the limits of self-contained aids, or a combination of both.

A landing maneuver unexpectedly discontinued below DA(H)/MDA(H) or beyond MAP.

The height above the ground or water of the base of the lowest cloud layer below 6000m (20,000ft) covering more than half the sky.

Reporting points that must be reported to ATC, designated on aeronautical charts by solid triangles or filed in a flight plan as fixes defining direct routes.

CDFA is a technique for flying the final approach of a Non-Precision Approach (NPA) as a continuous descent, supporting a stabilized approach procedure without level-off. It begins from an altitude/height at or above the FAF and continues to approximately 50 feet (15 meters) above the landing runway threshold or the point where the flare maneuver should begin for the specific aircraft type.

A specified altitude or height in a precision approach or approach with vertical guidance where a missed approach must be initiated if the required visual reference is not established.

The code word used to designate a distress phase.

Any flight by a two-turbine-engine aeroplane where the one-engine inoperative cruise time (in ISA and still air conditions) from any point on the route to an adequate alternate aerodrome exceeds the threshold time approved by the State of the Operator.

The fix from which the final approach (IFR) to an airport is executed, marking the beginning of the final approach segment. It is represented in the profile view of Jeppesen Terminal charts by a Maltese Cross for non-precision approaches and by the glide slope/path intercept point for precision approaches. The glide slope/path symbol starts at the FAF. When ATC directs a lower-than-published Glide Slope/Path Intercept Altitude, it is the resultant actual point of the glide slope/path intercept.

That segment of an instrument approach procedure in which alignment and descent for landing are accomplished.

A system for approach and landing operations that uses GNSS, augmented by a Ground-Based Augmentation System (GBAS), as the primary navigational reference.

An “umbrella” term adopted by the International Civil Aviation Organization (ICAO) to encompass any independent satellite navigation system enabling pilots to determine onboard position using satellite data.

An altitude derived by Jeppesen or provided by State Authorities, the Grid MORA altitude ensures terrain and man-made structure clearance within sections defined by latitude and longitude lines. MORA does not guarantee navaid signal or communication coverage.

Grid MORA values derived by Jeppesen provide 1000ft clearance in areas where the highest elevations are 5000ft MSL or lower and 2000ft clearance where elevations exceed 5001ft MSL. “Unsurveyed” Grid MORA indicates incomplete or insufficient data. Values followed by a +/- signify doubtful accuracy but are believed to provide sufficient reference point clearance.

Grid MORA (State) altitude, supplied by State Authorities, ensures 2000ft clearance in mountainous areas and 1000ft in non-mountainous areas.

Operations involving simultaneous take-offs and landings and/or simultaneous landings, where a landing aircraft is instructed by the controller to hold short of the intersecting runway, taxiway, or designated hold short point. Pilots must promptly inform the controller if the hold short clearance cannot be accepted.

A published altitude representing the maximum usable altitude or flight level for an airspace structure or route segment.

The lowest altitude at certain fixes that an aircraft must cross when proceeding toward a higher minimum enroute IFR altitude (MEA).

A specified altitude or height in a non-precision or circling approach below which descent is prohibited without the required visual reference.

The lowest published altitude between radio fixes or waypoints that ensures obstacle clearance and, in many countries, provides acceptable navigational signal coverage. The MEA applies across the full width of the airway, segment, area navigation route (low or high), or any other direct route between the defining radio fixes or waypoints.

The term used to describe a situation where an aircraft’s fuel supply has reached a point where little or no delay can be accepted.

NOTE: This is not an emergency but indicates that an emergency could arise if any undue delay occurs.

The Minimum Obstruction Clearance Altitude (MOCA) ensures a safe altitude above terrain while also guaranteeing VOR reception within 22 NM of the beacon. It provides terrain clearance as follows:

• 1,000 ft separation when terrain elevation is 5,000 ft or lower.

• 2,000 ft separation when terrain elevation exceeds 5,000 ft.

Route Minimum Off-Route Altitude (MORA) provides pilots with a minimum safe altitude to clear all obstacles within a 10 nautical mile (NM) radius of the route centerline, including 10 NM beyond route end fixes

MORA provides a minimum safe altitude to clear all obstacles within the defined area, typically 1,000 feet in non-mountainous areas and 2,000 feet in mountainous areas. 

The lowest altitude at which an intersection can be determined

The lowest altitude that provides a minimum clearance of 300m (1000ft) above all objects within a sector of a 46km (25NM) radius circle centered on a radio aid to navigation.

An area of changing terrain profile where the changes of terrain elevation exceed 900m (3000ft) within a distance of 10NM.

Non-intersecting runways whose extended centre lines have an angle of convergence/divergence of 15 degrees or less.

The lowest altitude or height above the relevant runway threshold or aerodrome elevation, as applicable, used to ensure compliance with obstacle clearance criteria.

A reduction in the vertical separation between FL290 – FL410 from 2000ft to 1000ft.

Provided for runways intended for night use or precision approach runways used by day or night, runway edge lights are fixed lights showing variable white, except that:

a. For a displaced threshold, lights between the runway’s beginning and the displaced threshold show red in the approach direction.
b. A section of lights—600m or one-third of the runway length, whichever is shorter—at the remote end of the runway from the takeoff start point may show yellow.

The distance over which a pilot on the runway centerline can see the surface markings or lights delineating the runway or identifying its centerline.

An instrument approach procedure can include up to four separate segments, depending on its structure.

a. Initial Approach — The segment of an instrument approach procedure between the initial approach fix and the intermediate approach fix or, where applicable, the final approach fix or point.

b. Intermediate Approach — The segment between the intermediate approach fix and the final approach fix or point, or between the end of a reversal, race track, or dead reckoning track procedure and the final approach fix or point, as appropriate.

c. Final Approach — The segment where alignment and descent for landing are accomplished.

d. Missed Approach Procedure — The procedure to follow if the approach cannot be continued.

a. Dry Snow — Snow that can be blown if loose or falls apart when compacted by hand; specific gravity: up to but not including 0.35.

b. Wet Snow — Snow that sticks together and tends to form a snowball when compacted by hand; specific gravity: 0.35 up to but not including 0.5.

c. Compacted Snow — Snow compressed into a solid mass that resists further compression and holds together or breaks into lumps when picked up; specific gravity: 0.5 and above.

A defined rectangular area at the end of the takeoff run available, prepared for stopping an aircraft in the event of an aborted takeoff.

• At least as wide as the runway and centered on its extended centerline.
• Capable of supporting the aircraft during an aborted takeoff without causing structural damage.
• Designated by airport authorities for use in decelerating the aircraft during an aborted takeoff.

The length of the take-off run available plus the length of the clearway, if provided.

The declared runway length available and suitable for an aircraft’s ground run during takeoff.

The height in the vicinity of an airport at or below which an aircraft’s vertical position is expressed relative to the airport reference datum.

The airspace between the transition altitude and transition level. Aircraft descending through the transition layer use altimeters set to local station pressure, while departing aircraft climbing through it use the standard altimeter setting (QNE) of 29.92 inches of mercury, 1013.2 millibars, or 1013.2 hectopascals.

The lowest flight level available for use above the transition altitude.

A fly-by waypoint requires turn anticipation to prevent overshooting the next flight segment.

A fly-over waypoint prevents any turn until it is overflown, followed by an intercept maneuver to the next flight segment.

WAAS is a navigation system developed for civil aviation, delivering highly accurate horizontal and vertical navigation for all aircraft classes in all flight phases, including enroute navigation, airport departures, and arrivals. It also enables vertically guided landing approaches in instrument meteorological conditions at all qualified locations.

Distance from the approach end of the runway to the start of the markings:

• 500′ Touchdown Zone: Three bars, 75′ long on each side of the centerline, marking the beginning of the fixed distance markers, spaced 500′ apart.
• 1000′ Fixed Distance Marker: One heavy bar on each side of the centerline, 150′ long and 30′ wide.
• 1500′: Two bars, 75′ long on each side of the centerline.
• 2000′: Two bars, 75′ long on each side of the centerline.
• 2500′: One bar, 75′ long on each side of the centerline.
• 3000′: One bar, 75′ long on each side of the centerline.

ICAO term is Rapid Exit Taxiway Indicator Lights (RETIL).

LDA or Distance Between Thresholds – Pairs of Markings:

• Less than 900m: 1 pair
• 900m to less than 1200m: 2 pairs
• 1200m to less than 1500m: 3 pairs
• 1500m to less than 2400m: 4 pairs
• 2400m or more: 6 pairs

When the paved surface before the threshold extends beyond 60m and is unsuitable for aircraft use, it will be fully marked with chevrons (preferably yellow) pointing toward the runway threshold.

a. The basic designator consists of a single letter followed by a number from 1 to 999. The letters are assigned as follows:

1. A, B, G, R – Routes that are part of the regional ATS route network and are not area navigation (RNAV) routes.
2. L, M, N, P – RNAV routes that are part of the regional ATS route network.
3. H, J, V, W – Routes that are not part of the regional ATS route network and are not RNAV routes.
4. Q, T, Y, Z – RNAV routes that are not part of the regional ATS route network.

b. If applicable, a supplementary letter is prefixed to the basic designator:

1. K – Indicates a low-level route primarily for helicopters.
2. U – Indicates that the route or a portion of it is in upper airspace.
3. S – Indicates a route designated exclusively for supersonic aircraft during acceleration, deceleration, and supersonic flight.

c. If applicable, a supplementary letter may be suffixed to the basic designator:

1. F – Indicates that only advisory service is provided on the route or a portion thereof.
2. G – Indicates that only flight information service is provided on the route or a portion thereof.
3. Y – For RNP1 routes at and above FL200, requiring turns between 30° and 90° to be executed within the tolerance of a tangential arc with a 22.5 NM radius.
4. Z – For RNP1 routes at and below FL190, requiring turns between 30° and 90° to be executed within the tolerance of a tangential arc with a 15 NM radius.

In voice communications, the basic letter of the designator should be pronounced using the ICAO spelling alphabet. Prefixes K, U, and S should be pronounced as follows:

• K = “Kopter”
• U = “Upper”
• S = “Supersonic”

The range of VHF transmissions is normally about 7% more than an actual line of sight, and can be determined by the formula:

a. General

1. The FAA developed WAAS to enhance the accuracy, integrity, and availability of GPS signals, enabling GPS to serve as the primary aviation navigation system from takeoff through approach. WAAS is a key component of the FAA’s strategic goal to establish a seamless satellite-based navigation system, improving both capacity and safety.
2. The International Civil Aviation Organization (ICAO) has established Standards and Recommended Practices (SARPs) for satellite-based augmentation systems (SBAS), including WAAS. Similar systems are being developed worldwide, such as EGNOS (European Geostationary Navigation Overlay System) in Europe and GAGAN (GPS and Geo-Augmented Navigation) in India. The integration of these systems will create a global navigation capability with improved accuracy, availability, and integrity compared to standalone GPS.

RNP Level and Typical Application with Primary Route Width (NM) – Centerline to Boundary

• RNP 0.1 to 1.0 – RNP AR Approach Segments: 0.1 to 1.0 NM
• RNP 0.3 to 1.0 – RNP Approach Segments: 0.3 to 1.0 NM
• RNP 1 – Terminal and En Route: 1.0 NM
• RNP 2 – En Route: 2.0 NM
• RNP 4 – Projected for oceanic/remote areas with 30 NM separation: 4.0 NM
• RNP 10 – Oceanic/remote areas with 50 NM lateral separation: 10.0 NM

True

MAGNETIC.

Ceiling And Visibility OK (CAVOK) replaces visibility, RVR, present weather, and cloud if:

1. Visibility is 10 km or more.
2. No cumulonimbus or towering cumulus, and no other cloud below 1,500 m (5,000 ft) or below the highest minimum sector altitude, whichever is greater.
3. No significant present weather.

• DR (Low Drifting): Phenomena occurring below 2 meters above ground.
• BL (Blowing): Phenomena occurring 2 meters or more above ground.
• GR (Hail): Hailstones 5mm or larger in diameter.
• GS (Small Hail): Hailstones less than 5mm in diameter.
• BR (Mist): Visibility 1,000m to 5,000m.
• FG (Fog): Visibility below 1,000m.
• VC (Vicinity): 8km to 16km from the aerodrome reference point.

• FEW – Few (1-2 oktas)
• SCT – Scattered (3-4 oktas)
• BKN – Broken (5-7 oktas)
• OVC – Overcast (8 oktas)

The Global Reporting Format (GRF) standardizes runway surface condition assessment, reporting channels, and operational use to ensure a harmonized international methodology for determining required take-off and landing distances.

The maximum validity of a SNOWTAM is reduced from 24 hours to 8 hours. If not replaced within this period, it automatically becomes invalid.

NOTAMN — New NOTAM
NOTAMR — Replaces a previous NOTAM
NOTAMC — Cancels a NOTAM
NOTAMS — SNOWTAM

Non-intersecting runways with extended centerlines converging or diverging at 15 degrees or less.

RHP

• One minute if at or below 4,250 m (14,000 ft).
• One and a half minutes if above 4,250 m (14,000 ft).

• Sector 1: Parallel entry (110°)
• Sector 2: Offset entry (70°)
• Sector 3: Direct entry (180°)

7500 – Unlawful interference/ Hijack
7600 – Communication Failure
7700 – Distress

Noise Abatement Departure Procedures (NADP)

1. NADP 1

• Power/thrust reduction at or above 240 m (800 ft) above aerodrome elevation.
• Flap/slat retraction delayed until reaching 900 m (3000 ft) above aerodrome elevation.
• At 900 m (3000 ft), accelerate, retract flaps/slats as scheduled, and transition to normal en-route climb.
• Initial climb speed to the noise abatement initiation point: V2 + 20 km/h (V2 + 10 kt).

2. NADP 2

• Flap/slat retraction begins at or above 240 m (800 ft) but before 900 m (3000 ft) above aerodrome elevation.
• Positive rate of climb maintained throughout flap/slat retraction.
• Intermediate flap retraction may occur below the minimum altitude if needed for performance.
• Power/thrust reduction occurs along the acceleration segment to ensure satisfactory acceleration.
• At 900 m (3000 ft), transition to normal en-route climb.
• Initial climb speed to the noise abatement initiation point: V2 + 20 km/h (V2 + 10 kt).

3. NADP A

• Takeoff to 450 m (1500 ft):
  • Takeoff power
  • Takeoff flaps
  • Climb at V2 + 20 to 40 km/h (V2 + 10 to 20 kt) (or as limited by body angle).
• At 450 m (1500 ft): Reduce thrust to no less than climb power/thrust.
• 450 m (1500 ft) to 900 m (3000 ft): Maintain V2 + 20 to 40 km/h (V2 + 10 to 20 kt).
• At 900 m (3000 ft): Accelerate smoothly to en-route climb speed with flap retraction on schedule.

• 4. NADP B

  • Takeoff to 300 m (1000 ft) above aerodrome elevation:
    • Takeoff power/thrust
    • Takeoff flaps
    • Climb at V2 + 20 to 40 km/h (V2 + 10 to 20 kt)
  • At 300 m (1000 ft):
    • Maintain a positive rate of climb
    • Retract flaps on schedule
    • Reduce thrust to normal climb power/thrust
  • From 300 m (1000 ft) to 900 m (3000 ft):
    • Continue climb at no more than VZF + 20 km/h (VZF + 10 kt)
  • At 900 m (3000 ft):
    • Smoothly accelerate to en-route climb speed.

Prohibition of Landing

Need for Special Precautions While Approaching or Landing

Horizontal white dumb-bell when displayed in a signal area indicates that aircraft are required to land, take-off and taxi on runways and taxiways only.

The same horizontal white dumb-bell but with a black bar placed perpendicular to the shaft across each circular portion of the dumb-bell when displayed in a signal area indicates that aircraft are required to land and take-off on runways only, but other maneuvers need not be confined to runways and taxiways.

Closed Runways or Taxiways

A) WINGWALKER/GUIDE

B) Identify Gate

C) STRAIGHT AHEAD

D) PROCEED TO NEXT SIGNALMAN OR AS DIRECTED BY TOWER/GROUND CONTROL

E) Turn

F) STOP

G) CHOCKS ON

H) DO NOT TOUCH CONTROLS (TECHNICAL/SERVICING COMMUNICATION SIGNAL)

I ) CONNECT GROUND POWER (TECHNICAL/SERVICING COMMUNICATION SIGNAL)

A) RECOMMENDED EVACUATION

B) RECOMMENDED STOP .RECOMMEND EVACUATION IN PROGRESS BE HALTED

C) EMERGENCY CONTAINED

D) FIRE

In the event of a 30-minute delay beyond the estimated off-block time for a controlled flight or a 60-minute delay for an uncontrolled flight.

a. SUPER (J): Aircraft types designated as such in Doc 8643, Aircraft Type Designators.
b. HEAVY (H): Aircraft with a maximum takeoff weight (MTOW) of 136,000 kg or more.
c. MEDIUM (M): Aircraft weighing more than 7,000 kg but less than 136,000 kg.
d. LIGHT (L): Aircraft with an MTOW of 7,000 kg or less.

• If in contact with ATC: Follow ATC instructions.
• If not in contact with ATC:
  • Turn left or right by 30 degrees and fly parallel for 5 NM (15 NM in oceanic airspace).
  • Climb or descend by 500 feet.
  • Turn on external lights.
  • Contact other aircraft on 121.5 MHz, 243 MHz, or 123.45 MHz.

Communication Failure Procedures

a. If in Visual Meteorological Conditions (VMC):

1. Continue flying in VMC.
2. Land at the nearest suitable aerodrome.
3. Report arrival to the appropriate ATC unit by the most expeditious means.

b. If in Instrument Meteorological Conditions (IMC) or unable to continue in VMC:

1. In procedural airspace (where procedural separation is applied):
   • Maintain last assigned speed and level (or minimum flight altitude, if higher) for 20 minutes after failing to report over a compulsory reporting point.
   • Thereafter, adjust level and speed as per the filed flight plan.
2. In airspace with ATS surveillance (radar, ADS-B):
   • Maintain last assigned speed and level (or minimum flight altitude, if higher) for 7 minutes after the later of:
     i. Reaching the last assigned level or minimum flight altitude.
     ii. Setting transponder to Code 7600 or ADS-B indicating loss of communication.
     iii. Failing to report over a compulsory reporting point.
   • Thereafter, adjust level and speed as per the filed flight plan.
3. If under radar vectoring or RNAV offset without a specified limit:
   • Rejoin the current flight plan route as soon as possible, but no later than the next significant point, considering minimum flight altitude.
4. Proceed via the current flight plan route to the designated navigation aid or fix serving the destination aerodrome.
   • Hold over this aid or fix if required for compliance with step 5.
5. Commence descent at or as close as possible to:
   • The expected approach time (EAT) last received and acknowledged.
   • If no EAT was received, use the estimated time of arrival (ETA) from the flight plan.
6. Conduct a normal instrument approach as specified for the designated navigation aid or fix.
7. Land, if possible, within 30 minutes of either:
   • The ETA from step 5.
   • The last acknowledged EAT, whichever is later.

Strategic Lateral Offset Procedures (SLOP)

SLOP are approved procedures allowing aircraft to fly on a parallel track up to 2 NM right of the centerline, relative to the direction of flight. This mitigates lateral overlap probability caused by increased navigation accuracy and reduces wake turbulence encounters.

An operator must ensure that meteorological visibility to CMV conversion is not used:

• For takeoff or when calculating any required RVR minimum below 800m.
• When reported RVR is available.
• When no Approach Lighting System (ALS) is available.
• If a landing minimum is charted as R550m (up to R750m) and no RVR is reported, the minimum visibility for landing is 800m.

Emergency Communication Frequencies

• VHF: 121.5 MHz
• UHF: 243.0 MHz
• HF: 500 kHz, 2182 kHz, 8364 kHz

Aircraft Classification Number (ACN)

A numerical value representing the relative impact of an aircraft on a pavement, based on a specified standard subgrade category. ACN values for selected aircraft types are provided by aircraft manufacturers or ICAO.

Pavement Classification Number (PCN)

PCN represents the bearing strength of a pavement for unrestricted operations and is determined and reported by the appropriate authority. It is qualified by pavement type, subgrade strength, tire pressure, and calculation method, using the following codes:

1. Pavement Classification Number (PCN):

• An aircraft with an ACN equal to or less than the reported PCN can operate on the pavement, subject to any tire pressure limitations.

2. Type of Pavement:

• R — Rigid
• F — Flexible

3. Subgrade Strength Category:

• A — High
• B — Medium
• C — Low
• D — Ultra-low

4. Tire Pressure Category:

• W — Unlimited, no pressure limit
• X — High, limited to 1.75 MPa (254 psi)
• Y — Medium, limited to 1.25 MPa (181 psi)
• Z — Low, limited to 0.50 MPa (73 psi)

5. Pavement Calculation Method:

• T — Technical evaluation
• U — Using aircraft experience

Example: PCN 80/R/B/W/T

Indicates a rigid pavement with a medium-strength subgrade, assessed by technical evaluation, having a PCN of 80, with no tire pressure limitation.

Blind Transmission

A transmission sent from one station to another when two-way communication cannot be established, but it is believed that the receiving station is able to receive the message.

2 hours.

150 ft

The minimum performance standard an aircraft must meet to be granted a Certificate of Airworthiness by the appropriate authority.

The average performance expected to be achieved by a fleet of the same aircraft type.

Net performance is derived by reducing gross performance in a specified manner to account for degradation factors that cannot be precisely measured, such as:

• Variation in operating techniques and maintenance practices.
• Performance degradation due to fleet aging.
• Environmental condition deviations from assumed standards.

Clearway

A defined rectangular area on ground or water over which an aircraft may conduct a portion of its initial climb to a specified screen height.

• Begins at the end of the runway (RWY).
• Maximum length is half the runway length.
• Minimum width extends 75 m (250 feet) on either side of the extended runway centerline.
• No obstacles or terrain should project above a plane sloping up at 1.25% from the end of the runway within the clearway.

Corrosive.

It is the Excepted Quantities Provision

Certain dangerous goods, when shipped in very small quantities, may be exempt from stringent dangerous goods regulations under the Excepted Quantities provision.

• Packages may be identified with an Excepted Quantities Label (Excepted Quantity Mark) instead of the standard hazard class labeling.
• The maximum allowable quantity per inner packaging and complete package varies based on the type of goods and the mode of transport (IATA, ADR, IMDG).
• A maximum of 1,000 packages is permitted per transport unit across all transport modes.
• Similar to Limited Quantities, not all dangerous goods qualify for shipment under this provision.

• Decision Altitude (DA) is referenced to mean sea level (MSL).
• Decision Height (DH) is referenced to the threshold elevation.

Eddy Dissipation Rate (EDR)

Eddy Dissipation Rate (EDR) is a measure of atmospheric turbulence intensity. It quantifies the rate at which turbulent kinetic energy dissipates in the atmosphere and is used in aviation to assess turbulence severity.

• Measured in m²/s³, with higher values indicating stronger turbulence.
• Considered an objective and standardized turbulence metric.
• Used in automated turbulence reporting systems for improved flight safety.

PANS OPS 3 is an ICAO document that establishes standardized procedures and guidelines for the design, review, and conduct of instrument flight procedures, ensuring safe and efficient aircraft operations under instrument flight rules.