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Technical Standard Order (TSO)-C65a, Airborne Doppler Radar Ground Speed and/or Drift Angle Measuring Equipment (For Air Carrier Aircraft)

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Notice of cancellation of Technical Standard Order (TSO)-C65a, Airborne Doppler Radar Ground Speed and/or Drift Angle Measuring Equipment (For Air Carrier Aircraft).


This notice announces the FAA's cancellation of TSO-C65a. The effect of the cancelled TSO will result in no new TSO-C65a design or production approvals. However, cancellation will not affect current production of articles with an existing TSO authorization (TSOA). Articles produced under an existing TSOA can still be installed per the existing airworthiness approvals.


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:



The Doppler radar ground speed and/or drift angle measuring equipment described by this TSO was used to provide inputs to semiautomatic self-contained dead reckoning navigation systems which were not continuously dependent on information derived from ground based or external navigation aids. The system employed radar signals to detect and measure ground speed and drift angle, using the aircraft compass system as its directional reference. This approach is less accurate than Inertial Navigation Systems (INS), and the use of an external reference is required for periodic updates if acceptable position accuracy is to be achieved on long range flights. Use of INS and Global Positioning System (GPS) has rendered TSO-C65a Doppler sensor equipment that provides inputs to dead reckoning navigation systems obsolete.

On August 18, 1983, the FAA published TSO-C65a. The FAA has no record of any TSO-C65a applications dating back to 1990. Our research indicates there are no new TSO-C65a applications in progress, and there are no authorized manufacturers manufacturing, advertising, or selling TSO-C65a compliant equipment. Given the obsolescence of the equipment, and the lack of industry interest in new TSO-C65a product design, the FAA is cancelling TSO-C65a.


Request for comments of our proposed cancellation of TSO-C65a as published in 77 FR 37470, June 21, 2012, produced no comments.


TSO-C65a is cancelled effective February 1, 2013.

Issued in Washington, DC, on August 28, 2012.

Susan J.M. Cabler,

Assistant Manager, Aircraft Engineering Division, Aircraft Certification Service.

[FR Doc. 2012-21632 Filed 8-31-12; 8:45 am]