| ACSI No.: | 17 |
| Issue No.: | 1 |
| Issue Date: | 1998-12-10 |
| AARD File: | 5009-3-17 |
Aircraft Certification Staff Instruction (ACSI)
Subject: AIRBORNE COLLISION AVOIDANCE SYSTEMS (ACAS) AND TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEMS (TCAS)
Table of Contents
5.0 REQUIREMENTS TO EQUIP WITH TCAS
7.1 Approval - General
7.2 Aircraft Installation Approval
7.3 TCAS Flight Testing
7.3.1 Flight Test Requirements and Support
7.3.2 Flight Test Guidance
7.3.3 Aircraft Flight Manual Supplement (AFMS)
7.3.4 Regional Flight Test Witnessing
8.0 MODE S TRANSPONDER APPROVAL AND UNIQUE CODES
1.0 Background
The Federal Aviation Administration (FAA) requires the installation and operation of Traffic Alert and Collision Avoidance Systems (TCAS) in commercial aircraft certified with 10 seats or greater and flying in U.S. airspace. Since its introduction in late 1991, TCAS technology and its operational use have matured. TCAS certification is no longer a Transport Canada Headquarters function as all Regions have become qualified to issue TCAS approvals, including the airworthiness review of foreign TCAS STCs. The ICAO designation for such systems is Airborne Collision Avoidance system (ACAS).
2.0 Purpose
The purpose of this ACSI is to provide HQ and Regional Aircraft Certification personnel, including delegates with guidance for the airworthiness approval of TCAS and operational considerations.
3.0 References
- AC 20-131A - Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II) and Mode S Transponders, dated 3/29/93 or later revisions.
- ASI 22 - Modification Approval Procedures.
- ACPL No. 6 - Review of foreign STCs.
- ACSI No. 5 - Mode S Transponder Approvals.
- FAA Technical Standard Order, TSO C119A or later revisions.
- FAA Technical Standard Order, TSO C-118 or later revisions.
- ACSI 43 - Regional Flight Test Procedures.
4.0 General Information
The TCAS II system consists of a computer, pilot displays, a mode S transponder, modified instantaneous vertical speed indicators, controls, wiring and antenna(s). The system will display proximate traffic, and provides traffic advisories and resolution advisories.
4.1 Definitions
- A Resolution Advisory (RA) is a voice command and visual guidance provided by TCAS II to avoid a potential collision.
- A Traffic Advisory (TA) is a caution presented to the pilot to inform him of the position of another aircraft in the immediate vicinity.
NOTE:
In order to provide Traffic Advisories, other aircraft must at minimum be equipped with a functioning transponder with or without an altitude encoding capability. In order to provide Resolution Advisories to prevent collisions, other aircraft must be equipped with a functioning transponder that has altitude encoding capability. In an encounter between two TCAS II equipped aircraft, their computers will communicate and coordinate to provide complementary Resolution Advisories. Aircraft without transponders are invisible to TCAS equipped aircraft.
- TCAS I is a functional subset of TCAS II in that it provides Traffic Advisories only and does not command any maneuvers.
- Traffic and Collision Avoidance Device (TCAD) is a generic term applied to less sophisticated equipment which can determine bearing, range and altitude of transponder equipped aircraft , and display such targets on a cockpit display. These systems generally lack the bearing accuracy and detection range of TCAS I and TCAS II. No maneuvers are commanded. TCAD is not required by regulation and it is considered a non essential advisory system only. As such , its installation is approved on a non hazard basis.
5.0 Requirements to Equip with TCAS
For Canadian registered aeroplanes wishing to operate in United States airspace, the following apply (Ref FAR 129.18):
- TCAS I is required for Commercial Aeroplanes with 10 to 30 Passenger Seats.
- TCAS II is required for Commercial Aeroplanes with more than 30 Passenger Seats.
6.0 Transport Canada Position
Transport Canada has not mandated TCAS installation but encourages the installation of the system.
7.0 Approvla Requirements
7.1 Approvals - General
Airworthiness and operational approval for Canadian operators must be obtained from Transport Canada before TCAS systems are operated in Canadian airspace. Prior to operation in the United States airspace, airworthiness and operational approvals must be obtained from the FAA through Transport Canada.
7.2 Aircraft Installation Approval
7.2.1 Application for Canadian and foreign approvals of TCAS installations should be submitted to Transport Canada Regional Aircraft Certification offices in accordance with ASI No. 22 guidelines. TCAS installations incorporated on imported aircraft must be reviewed in accordance with the provisions set forth in ACPL No. 6.
7.2.2 Where requesting an airworthiness approval, the method specified in FAA Advisory Circular AC20131A provides an acceptable means of demonstrating compliance with the appropriate requirements of Airworthiness Manual, Chapter 525.
7.3 TCAS Flight Testing
7.3.1 Flight Test Requirements and Support
Flight evaluation requirements and required support from Headquarters will be provided in accordance with the guidelines specified in ACSI No. 43. The appropriate flight test data should be submitted to Aircraft Certification Flight Test division early in the program.
7.3.2 Flight Test Guidance
Specific guidance on cockpit installation aspects and the flight tests required for Mode S (Ref. ACSI No. 5) and TCAS equipment installations is available on request from Aircraft
7.3.3 Aircraft Flight Manual Supplement (AFMS)
Guidance on the preparation of a suitable AFMS for Mode S and TCAS is available on request from Aircraft Certification Flight Test.
7.3.4 Regional Flight Test Witnessing
Unless special considerations prevail, Aircraft Certification Flight Test will not normally participate in flight testing of TCAS equipment installations. Aircraft Certification Flight Test staff should, however, be consulted for guidance as necessary.
The RMAC may designate a suitably qualified individual to witness any required flight test. The individual should have demonstrated past relevant capability to witness the appropriate flight test.
8.0 Mode S Transponder Approval and Unique Codes
Mode S transponders perform all the functions of Mode A and C transponders, and have data link capability. Mode S transponders are required for TCAS II. A Mode S transponder may be installed to replace a Mode A or C transponder without necessitating the installation of a TCAS. Each Canadian registered aircraft with a Mode S transponder must receive a unique code assignment through their Transport Canada General Aviation Division
NOTE:
For details on Mode S Transponder installation approvals, refer to ACSI No. 5.
9.0 TCAS Self Test
The TCAS self test feature suspends normal TCAS function while the test is in progress from 8 to 25 seconds. Since the TCAS has diagnostic functions running at all times when powered up, there is no reason for a pilot initiated self test in flight. Accordingly, it has been Transport Canada's policy to require the Self Test feature to be de-activated in flight. However, this policy has often caused engineering changes, approval delays and additional costs to operators for aircraft imported with this feature not deactivated.
The activation of the TCAS Self Test feature in flight should continue to be strongly discouraged for all new TCAS installations in Canada. Imported aircraft may be accepted with this feature. However, consideration should be given to maintaining a consistent configuration in an operator's fleet.
10.0 Operational Approval
TCAS II operational approval is obtained through Transport Canada Commercial and Business Aviation Division. The local Regional Office should be contacted.
Original signed by:
K. Mansfield
Director, Aircraft Certification