[Federal Register Volume 62, Number 238 (Thursday, December 11, 1997)]
[Notices]
[Pages 65305-65306]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-32451]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Traffic Advisory System (TAS) Airborne Equipment

AGENCY: Federal Aviation Administration.

ACTION: Notice of availability for public comment.

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SUMMARY: This notice announces the availability of and requests 
comments on a proposed Technical Standard Order (TSO) pertaining to 
traffic advisory system (TAS) airborne equipment. The proposed TSO 
prescribes the minimum operational performance standards that traffic 
advisory system (TAS) airborne equipment must meet to be identified 
with the marking ``TSO-C147.''

DATES: Comment must identify the TSO file number and be received on or 
before February 20, 1998.

ADDRESSES: Send all comments on the proposed technical standard order 
to: Technical Programs and Continued Airworthiness Branch, AIR-120, 
Aircraft Engineering Division, Aircraft Certification Service, Federal 
Aviation Administration, 800 Independence Avenue, SW., Washington, DC 
20591. Or deliver comments to: Federal Aviation Administration, Room 
815, 800 Independence Avenue, SW., Washington, DC 20591. Comment must 
identify the TSO file number.

FOR FURTHER INFORMATION CONTACT: Ms. Bobbie J. Smith, Technical 
Programs and Continued Airworthiness Branch, AIR-120, Aircraft 
Engineering Division, Aircraft Certification Service, Federal Aviation 
Administration, 800 Independence Avenue, SW., Washington, DC 20591, FAX 
No. (202) 267-5340.

Comments Invited

    Interested persons are invited to comment on the proposed TSO 
listed in this notice by submitting such written data, views, or 
arguments as they desire

[[Page 65306]]

to the above specified address. Comments received on the proposed 
technical standard order may be examined, before and after the comment 
closing date, in Room 815, FAA Headquarters Building (FOB-10A), 800 
Independence Avenue, SW., Washington, DC 20591, weekdays except Federal 
holidays, between 8:30 a.m. and 4:30 p.m. All communications received 
on or before the closing date for comments specified above will be 
considered by the Director of the Aircraft Certification Service before 
issuing the final TSO.

Background

    This TSO is proposed for a new system of airborne equipment 
designated TAS. TAS is an airborne traffic advisory system that 
interrogates ATC transponders in nearby aircraft and uses computer 
processing to identify and advise the crew of potential and predicted 
collision threats. The system is designed to protect a volume of 
airspace around the TAS equipped aircraft by assisting pilots in the 
visual acquisition of intruder traffic. TAS is similar to TCAS I with 
changes in the power output and display requirements that make it more 
encomical, and therefore more appealing, to the General Aviation 
community. There are two classes of TAS equipment:

Class A. Traffic Display and Aural Alerting

    Class A systems provide a flight deck traffic display that 
indicates the relative position and altitude of ATC transponder-
equipped aircraft. Class A systems will provide appropriate aural and 
visual advisories to assist the flightcrew in visually acquiring the 
threat aircraft when TAS predicts a penetration of the protected 
airspace. TAS assist the flightcrew in visually acquiring the intruding 
aircraft. Traffic advisories indicate the relative positions of 
intruding aircraft that meet certain range and altitude criteria and 
are approximately 30 seconds from the closest point of approach. 
Traffic advisories can be generated for aircraft with operative Mode S, 
Mode C or Mode A (non-altitude reporting) transponders. The aural alert 
message ``Traffic-Traffic,'' spoken once, shall be used to inform the 
crew of a Traffic Advisory (TA). The TAS equipment is viewed as a 
supplement to the pilot who, with the aid of the ATC system, has the 
primary responsibility for avoiding mid-air collisions. The TAS system 
provides no indication of aircraft without operative transponders.

Class B. Aural Alerting and Annunciation Only

    Class B systems do not include a cockpit traffic display. Class B 
systems will provide appropriate aural advisories and visual 
annunciations to assist the flightcrew in visually acquiring the threat 
aircraft when TAS predicts a penetration of the protected airspace. 
Traffic advisories indicate the relative positions of intruding 
aircraft that meet certain range and altitude criteria and are 
approximately 30 seconds from the closest point of approach. They 
assist the flightcrew in visually acquiring the intruding aircraft. The 
aural alert message ``Traffic-Traffic,'' spoken once, shall be used to 
inform the crew of a Traffic Advisory (TA). This aural alert message 
will be accompanied by a discrete visual annunciation indicating that a 
TA is currently active. This annunciation will remain as long as the TA 
is active and will extinguish when no TAs are active. TAs will, upon 
crew command, generate an aural message defining the relative position 
of ATC transponder-equipped aircraft. Traffic advisories can be 
generated for aircraft with operative Mode S, Mode C, or Mode A (non-
altitude reporting) transponders. The TAS equipment is viewed as a 
supplement to the pilot who, with the aid of the ATC system, has the 
primary responsibility for avoiding mid-air collisions. The TAS system 
provides no indication of aircraft without operative transponders. RTCA 
Document No. DO-160C sets forth the environmental standards for the 
Traffic Advisory System. RTCA Document DO-178B sets forth the minimum 
performance requirements for software for the Traffic Advisory System 
and requires that each article be marked with the appropriate software 
level. Because the proposed TSO calls for 2 classes of equipment, the 
TSO also requires that each article be marked as equipment Class A or 
Class B, as applicable.
    The minimum performance standards for this Traffic Advisory System 
TSO differ slightly from those standards in RTCA DO-197 (TCAS 1). This 
TSO was developed specifically, but not exclusively for the general 
aviation market. The Traffic Advisory System has a lower radiated power 
output than TCAS 1 and gives an alert as to the presence of intruder 
aircraft. However, TCAS 1 has resolution alert that gives the pilot 
directional commands when intruder aircraft are present. These 
differences make the Traffic Advisory System more economical for the 
general aviation community. The exceptions to RTCA DO-197A are detailed 
in the Appendix 1 of this TSO. In order to comply with TSA-C147, the 
applicant must also meet the performance standards set forth in RTCA 
Document No. DO-197A, with the stated exceptions in Appendix 1.

How To Obtain Copies

    A copy of the proposed TSO-C147 may be obtained via Internet 
(http://www.faa.gov/avr/air/100home.htm) or on request from the office 
listed under ``For Further Information Contact.'' Copies of RTCA, Inc. 
Document No. DO-197A, ``Minimum Operational Performance Standards for 
An Active Traffic Alert and Collision Avoidance System I (ACTIVE TCAS 
1),'' dated September 12, 1994. RTCA Document No. 160D, ``Environmental 
Conditions and Test Procedures for Airborne Equipment,'' dated July 29, 
1997; and RTCA Document No. DO-178B, ``Software Considerations in 
Airborne Systems and Equipment Certification,'' dated 1, 1992, may be 
purchased from the RTCA Inc., 1140 Connecticut Avenue, NW., Suite 1020, 
Washington, DC 20036.

    Issued in Washington, DC, on December 5, 1997.
Henri P. Branting,
Acting Manager, Aircraft Engineering Division, Aircraft Certification 
Service.
[FR Doc. 97-32451 Filed 12-10-97; 8:45 am]
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