[Federal Register Volume 77, Number 121 (Friday, June 22, 2012)]
[Pages 37733-37734]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-15237]



Federal Aviation Administration

Technical Standard Order (TSO)-C68a, Airborne Automatic Dead 
Reckoning Computer Equipment Utilizing Aircraft Heading and Doppler 
Ground Speed and Drift Angle Data (for Air Carrier Aircraft)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of intent to cancel Technical Standard Order (TSO)-C68a, 
Airborne automatic dead reckoning computer equipment utilizing aircraft 
heading and Doppler ground speed and drift angle data (for air carrier 


SUMMARY: This notice announces the FAA's intent to cancel TSO-C68a, 
Airborne automatic dead reckoning computer equipment utilizing aircraft 
heading and Doppler ground speed and drift angle data. The effect of 
the cancelled TSO-68a will result in no new TSO-C68a design or 
production approvals.

DATES: Comments must be received on or before July 23, 2012.

FOR FURTHER INFORMATION CONTACT: Mr. Albert Sayadian, AIR-130, Federal 
Aviation Administration, 470 L'Enfant Plaza, Suite 4102, Washington, DC 
20024. Telephone (202) 385-4652, fax (202) 385-4651, email to: 


Comments Invited

    You are invited to comment on the cancellation of the TSO-C68a by 
submitting written data, views, or arguments to the above address. 
Comments received may be examined, both before and after the closing 
date at the above address, weekdays except Federal holidays, between 
8:30 a.m. and 4:30 p.m. The Director, Aircraft Certification Service, 
will consider all comments received on or before the closing date.


    Doppler radar is a semiautomatic self-contained dead reckoning 
navigation system (radar sensor plus computer) which is not 
continuously dependent on information derived from ground based or 
external aids. The system employs radar signals to detect and measure 
ground speed and drift angle, using the aircraft compass system as its 
directional reference. Doppler is less accurate than Inertial 
Navigation System (INS), however, and the use of an external reference 
is required for periodic updates if acceptable position

[[Page 37734]]

accuracy is to be achieved on long range flights. Use of INS and Global 
Positioning System (GPS) has rendered TSO-C68a systems obsolete. The 
FAA has no record of any applications for TSO-C68a since it was 
published in 1983. Given the obsolescence of the equipment and the lack 
of industry interest in TSO-C68a product designs, we propose cancelling 

    Issued in Washington, DC, on June 18, 2012.
Susan J.M. Cabler,
Assistant Manager, Aircraft Engineering Division, Aircraft 
Certification Service.
[FR Doc. 2012-15237 Filed 6-20-12; 8:45 am]