Advisory Circular (AC) No. 302-012

International Civil Aviation Organization Type A Obstacle Charts

Issuing Office: Civil Aviation
AC 302-012
File Classification No.: Z 5000-34 Issue No.: 01
RDIMS No.: 4456252-V17 Effective Date: 2012-04-24


  1. This Advisory Circular (AC) is provided for information and guidance purposes. It describes an example of an acceptable means, but not the only means, of demonstrating compliance with regulations and standards. This AC on its own does not change, create, amend or permit deviations from regulatory requirements, nor does it establish minimum standards.

1.1  Purpose

  1. The purpose of this document is to provide information, guidance, roles and responsibilities for the preparation, completion, publishing, and amendment of International Civil Aviation Organization (ICAO) Type A – Obstacle Charts, in accordance with recognized international standards and guidance.

1.2  Applicability

  1. This document applies to all operators of airports designated for international commercial flight operations, international air operators, aeronautical information service providers, Transport Canada Civil Aviation (TCCA) Headquarters (HQ) and regional personnel. This guidance is also available to the aviation industry for information purposes.

1.3  Description of Changes

  1. Not applicable.


2.1  Reference Documents

  1. It is intended that the following reference materials be used in conjunction with this document:

    1. Aeronautics Act (R.S., 1985, c. A-2);

    2. Civil Air Navigation Services Commercialization Act (CANSCA), Assented to 20th June, 1996;

    3. Part III, Subpart 02 of the Canadian Aviation Regulations (CARs)—Airports;

    4. Part VIII, Subpart 03 of the CARsAeronautical Information Services;

    5. ICAO Annex 4 to the Convention on International Civil Aviation– Aeronautical Charts;

    6. ICAO Annex 9 to the Convention on International Civil Aviation– Facilitation;

    7. ICAO Annex 11 to the Convention on International Civil Aviation– Air Traffic Services;

    8. ICAO Annex 15 to the Convention on International Civil Aviation—Aeronautical Information Services;

    9. Transport Canada Publication (TP) 312, —Aerodrome Standards and Recommended Practices;

    10. TP 14371, Transport Canada Aeronautical Information Manual (TC AIM); and

    11. NAV CANADA publication – AIP Canada (ICAO)

2.2  Cancelled Documents

  1. As of the effective date of this document, the following document is cancelled:

    1. Aerodrome Safety Circular (ASC) 2001-009, Issue 1, dated 2001-07-10— ICAO Type A Obstacle Charts.

  2. By default, it is understood that the publication of a new issue of a document automatically renders any earlier issues of the same document null and void.

2.3  Definitions and Abbreviations

  1. The following definitions are used in this document:

    1. Aeronautical chart: a representation of a portion of the Earth, its culture and relief, specifically designated to meet the requirements of air navigation as defined by ICAO Annex 4;

    2. Aeronautical information services: the services necessary to meet the requirements of Annexes 4 and 15 to the Convention that relate to aeronautical information; and

    3. Obstacle: all fixed (whether temporary or permanent) and mobile objects, or parts thereof, that are located on an area intended for the surface movement of aircraft or that extend above a defined surface intended to protect aircraft in flight.

      Note: The term obstacle is used in ICAO Annex 4 solely for the purpose of specifying the charting of objects that are considered a potential hazard to the safe passage of aircraft in the type of operation for which the individual chart series is designed.

  2. The following abbreviations are used in this document:

    1. AIS: Aeronautical Information Services; and

    2. ICAO: International Civil Aviation Organization;


  1. Prior to June 1996, the International Civil Aviation Organization (ICAO) Type A Obstacle Charts were produced for and under the authority of the Minister of Transport. Operators of Canadian international airports and some others that served large commercial aircrafts were required by section 2.3.4 of Transport Canada Publication (TP) 312 to provide to the certifying authority Transport Canada Civil Aviation (TCCA) detailed survey data of significant obstructions in the take-off flight path of each runway used by international air operators.

  2. On June 20th, 1996 the Civil Air Navigation Services Commercialization Act (CANSCA) respecting the commercialization of civil air navigation services (BILL C-20) received royal assent. The Act transferred the management and control of air navigation services from the Minister of Transport to the new corporation NAV CANADA.

  3. Part II of the Aeronautics Act, designated NAV CANADA as the authority in Canada responsible for providing aeronautical information services for the purposes of Annex 4 and 15 to the Chicago Convention and air traffic control services for the purposes of Annex 11 to the Chicago Convention. As such, the production and publication of ICAO Type A Obstacle Charts is the responsibility of NAV CANADA in accordance with CANSCA.

  4. Subsection 803.01(2) of the Canadian Aviation Regulations (CARs) states: "No person shall provide aeronautical information services except in accordance with the standards set out in Annexes 4 and 15 to the Convention."

  5. Airports designated for international commercial flights operations may be referred to as international airports for the purpose of this document.

  6. International airport operators are required to comply with ICAO Type A Obstacle Charts standards. They also have to make those Charts available for international air operators.

  7. Air operators use obstacle data provided in the format of an ICAO Type A Chart for operational planning purposes only. Obstacles identified using the Type A Obstacle Charts criteria are not limiting for an airport, although it may be limiting for an air operator.


4.1  Airport Operators

  1. Operators of airports that receive international air operations are responsible for compiling aeronautical data used in the development and production of ICAO Type A Obstacle Charts. Excluded are those airports whose only international air operations are between the United States and Canada. These air operations classified in Canada, as transborder air operations, are not necessary subject to all ICAO Annex 9 – Facilitation standards.

  2. In accordance with section 2.3.4 of TP 312, the airport operators of each airport provide to NAV CANADA – AIS Data Collection Division the obstacle information needed to compile and produce the Type A Obstacle Charts for all runway departure paths used by international air operators in agreement with international requirements.

  3. In addition, the operators advise and provide the aeronautical data to TCCA Regional Office, in order to verify compliance with the standards.

  4. To meet Canada's obligations as an ICAO member State and in accordance with Subpart 302 of the CARs and associated section 2.3.4 of TP 312, the following information needs to be provided to the AIS service provider for each runway take-off flight path area, intended to be used by international commercial air operators as follows:

    1. runway designation;

    2. runway true bearing, length, width, and surface type;

    3. length and width of the clearway, if provided;

    4. dimensions of the take-off flight path area;

    5. runway threshold and departure end elevations;

    6. location, height above mean sea level (MSL), and nature of objects within the take-off flight path area identified as obstacles; and

    7. the date the obstacle survey was completed.

  5. In addition to the mandatory chart information specified in the aerodrome standards, the following data should be provided with the survey package when possible, to facilitate the processing of the aeronautical data:

    1. magnetic variation;

    2. obstacles lateral distance from the runway centreline;

    3. measurements in feet to avoid conversion errors; and

    4. only the obstacles located inside the defined take-off flight path area.

4.2  Transport Canada Civil Aviation Regional Office

  1. The operator's respective TCCA regional office should be copied or informed during the process of exchanging survey information between the airport operator and NAV CANADA (the aeronautical information service provider).

  2. For more information, please contact a TCCA Regional Office which can be found at the following address:

4.3  Aeronautical Information Service Provider, NAV CANADA Inc.

  1. In order to develop and produce ICAO Type A Obstacle Charts, the following steps are followed by NAV CANADA:

    1. Receive and compile verified survey data from airport operator;

    2. Complete charts draft;

    3. Send the draft charts back to the airport operator for further information verification and final approval;

    4. When approval is received from the airport operator, remove the "Draft" label on the charts;

    5. Publish the charts;

    6. Advertise their availability in the Aeronautical Information Publication (AIP) Canada (ICAO);

    7. Aeronautical Information Regulation and Control (AIRAC) cut-off dates must be respected during the completion of this process.


5.1  New charts

  1. The operator of an international airport requiring a new ICAO Type A Obstacle Chart shall have the airport surveyed in accordance with the requirements set out in Chapter 3 of Annex 4, Aerodrome Obstacle Chart—ICAO Type A (Operating Limitations) and in Section 2.3.4 of TP 312. This survey (clearly identifying which obstacles are to be depicted) will be sent to NAV CANADA and the appropriate TCCA regional office for verification. The date of the survey will be clearly indicated on the survey document.

  2. Appendix A illustrates what obstacle data is needed by NAV CANADA to prepare a Type A Obstacle Chart. International airport operators submitting information must supply the obstacle data using this or an equivalent format.

  3. A copy of Annex 4 to the Convention on International Civil Aviation – Aeronautical Charts can be ordered using the following e-SHOP link from the ICAO Web site:

5.2  Revised charts

  1. TCCA Standards requires that an obstacle survey shall not exceed 5 years between surveys in accordance with section of TP 312 or as determined by the certifying authority, taking into consideration the level of building activity in the area. It has to be noted that a survey is not required if it can be ascertained and reported that there are no new obstacles in the take-off flight path area. In that case, the date of this confirmation statement will appear on the chart.

  2. Sending the info package 6 months prior to the 5 years deadline is considered a good practice in order to give NAV CANADA enough time to produce and publish the charts.

  3. If a correction is required, either the current chart with appropriate markings indicated or the survey data shall be submitted to NAV CANADA by the airport operator specifying what obstacle is to be deleted and/or added on the chart since the last publication.

5.3  Conclusion

  1. Understanding the ICAO Type A Obstacle Charts requirements will contribute to the timely dissemination of this information to industry users.

  2. In summary, NAV CANADA – AIS is responsible for drafting/revising the chart as requested, labelling it as "DRAFT" and returning it to the operator for verification. When the airport operator has agreed with the draft chart, a written statement to that effect will be given to the NAV CANADA – AIS, who will then remove the "DRAFT" label, have the chart published and advertise its availability in the next amendment of the AIP Canada (ICAO) that can be obtained on the NAV CANADA web site at:


  1. Not applicable.


  1. Not applicable.


For more information, please contact the:
TCCA Regional Offices:

Web Link:

Suggestions for amendment to this document are invited, and should be submitted via the Standards Branch "AART Documentation Services" mailbox at the following e-mail address:

Original signed by

Aaron McCrorie
Director, Standards
Civil Aviation
Transport Canada


  1. RUNWAY and CLEARWAY DATA: Provide information on the length, width and profile of each runway and clearway.

  2. LIST OF OBSTACLES: Provide a list of the obstacles to be depicted at each end of the runway as shown in the sample list. Specify where the ground distance is measured from, whether it is the end of the clearway (line A-B) or the bottom of the departure runway.


    Number Type of Feature Elevation
    (Feet ASL)
    Ground Distance
    (from line A-B)
    Ground Distance off Centreline
    (from line C-D)
    1. Lamp Standard 155.95 2195.05 -410.11
    2. Tree-top 172.52 3500.10 75.54
    3. Tree-top 195.77 5090.20 -767.25
  3. PROFILE VIEW: It is required to show obstacles which penetrate the 1.2% slope. It is not required to show obstacles in the shadow (See Reference: ICAO Annex 4, Chapter 3, Paragraph of a previous obstacle even if it penetrates the 1.2% slope.

    Diagram C. Profile View:

    Text Description

    Diagram C: Profile View

    The Profile view requires to show obstacles which penetrate the 1.2% slope. It is not required to show obstacles in the shadow (See Reference: ICAO Annex 4, Chapter 3, Paragraph of a previous obstacle even if it penetrates the 1.2% slope.

    Diagram C gives an example of a Type A Obstacles Charts Profile View depicting the location of each obstacle penetrating the 1.2% slope with its elevation above sea level (ASL) and its distance from the end the runway or clearway.

    Vertical axis represents the elevation in feet of each obstacle (Above Sea Level).
    Horizontal axis represents the distances in feet from the runway threshold.

    In the example provided, obstacles distance is measured from the end of the clearway.
    Runway length is 7000 feet and clearway length is 1000 feet. So all distance measurements start from 8000 feet (end of clearway: line A-B).
    Only obstacles penetrating the 1.2% slope are represented.

    In that example, number 1 depiction represents the obstacle listed in table B as a "Standard Lamp" and number 2 and 3 represent the obstacles listed in table B as "Tree Tops".
    Number 1 obstacle's elevation is 155.95 feet (ASL) and its distance is 2195.05 feet from the end of the clearway located at 8000 feet from the threshold (Number 1 is 10 195.05 feet from the threshold).
    Number 2 obstacle's elevation is 172.52 feet (ASL) and its distance is 3500.10 feet from the end of the clearway located at 8000 feet from the threshold (Number 2 is 11 500.10 feet from the threshold).
    Number 3 obstacle's elevation is 195.77 feet (ASL) and its distance is 5090.20 feet from the end of the clearway located at 8000 feet from the threshold (Number 3 is 13 090.20 feet from the threshold).
    All elevations and ground distances correspond to the scales represented on the vertical and horizontal axis.

  4. PLAN VIEW: It is required to show obstacles within the area of the splay.

    Diagram D. Plan View:

    Text Description

    The Plan View requires to show obstacles within the area of the splay in the take-off flight path area.

    Diagram D gives an example of a Type A Obstacles Charts Plan View depicting the location of each identified obstacle penetrating the 1.2% slope in the take-off flight path area with its elevation (rounded) above sea level.

    The Plan View shows a depiction of the runway, the clearway and the Type A Obstacle Chart splay of the take-off flight path area.
    Inside that splay are depicted all obstacles penetrating the 1.2% slope.
    The clearway length is 1000 feet (maximum allowed) and its width is 600 feet.
    Line A-B represents the end of the clearway from where all obstacle distances are measured.
    Line C-D represents runway and clearway centreline extension.
    Obstacles 1, 2 and 3 are depicted at ground distances corresponding to those provided in Table B, from Line A-B.
    Obstacle 1 shows an elevation of 156 feet (155.95 feet rounded).
    Obstacle 2 shows an elevation of 173 feet (172.52 feet rounded).
    Obstacle 3 shows an elevation of 196 feet (195.77 feet rounded).
    The signs + and - specify which side of the runway centreline extension (line C-D) is located each obstacle.

    This information provided by professional and recognized surveyors will be sent to NAV CANADA. The Type A Obstacles Chart that will be published by NAV CANADA might be similar to the example provided in the "ICAO Type A Obstacle Charts Advisory Circular" or it may present minor differences in its finalized version, but all the information specified in this example needs to be provided.

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