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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 intent to cancel 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 intent to cancel TSO-C65a, Airborne Doppler radar ground speed and/or drift angle measuring equipment (for air carrier aircraft).

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. Articles produced under an existing TSOA can still be installed per the existing airworthiness approvals, and all applications for new airworthiness approvals will still be processed.


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


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-C65a 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.


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, Airborne Doppler radar ground speed and/or drift angle measuring equipment (for air carrier aircraft). The FAA has no record of any TSO-C65a applications from 1990 onward. Our research indicates no new TSO-C65a applications are in progress, and no authorized manufacturers are 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 designs, we propose cancelling TSO-C65a.

Issued in Washington, DC, on June 18, 2012.

Susan J.M. Cabler,

Assistant Manager, Aircraft Engineering Division, Aircraft Certification Service.

[FR Doc. 2012-15209 Filed 6-20-12; 8:45 am]