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###### Department of Transportation

###### Federal Aviation Administration

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Notice of intent to cancel Technical Standard Order (TSO)-C129a, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS), and request for public comment.

# SUMMARY:

This notice announces the FAA's intent to cancel TSO-C129a, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS). The effect of the cancelled TSO will result in no new TSO-C129a design or production approvals. However, cancellation will not affect production according to an existing TSO authorization (TSOA). Articles produced under an existing TSOA can still be installed according to existing airworthiness approvals and applications for new airworthiness approvals will still be processed.

# DATES:

Comments must be received on or before September 15, 2011.

# FOR FURTHER INFORMATION CONTACT:

                        Mr. Kevin Bridges, AIR-130, Federal Aviation Administration, 470 L'Enfant Plaza, Suite 4102, Washington, DC 20024. Telephone (202) 385-4627, fax (202) 385-4651, e-mail to:                         *kevin.bridges@faa.gov.*

# SUPPLEMENTARY INFORMATION:

## Comments Invited

You are invited to comment on the cancellation of the TSO 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.

## Background

                    On September 21, 2009, the FAA published TSO-C196, Airborne Supplemental Navigation Sensors for Global Positioning System Equipment Using Aircraft-Based Augmentation; an updated minimum performance standard for GPS sensors not augmented by satellite-based or ground-based systems (                    *i.e.,*                     TSO-C129a Class B and Class C). The FAA has also published two GPS TSOs augmented by the satellite-based augmentation system (TSO-C145c, Airborne Navigation Sensors Using the Global Positioning System Augmented by the Satellite-Based Augmentation System; and, TSO-C146c, Stand-Alone Navigation Equipment Using the Global Positioning System Augmented by the Satellite-Based Augmentation System).                

                    TSO-C145c, TSO-C146c, and TSO-C196 incorporate more stringent standards that make the GPS equipment more accurate and robust than sensors                           ( print page 50809)                        built to the minimum requirements in TSO-C129a. Two examples of these improvements are: (1) A requirement for the receiver to properly account for satellite range error if it is reflected in the User Range Accuracy index (commonly referred to as being “Selective Availability aware”); and, (2) requirements to ensure performance is not degraded due to an increasing radio frequency noise environment as other satellite systems become available.                

Since 1995, there has been one application for TSOA for TSO-C129a. Therefore, we believe that it is appropriate to cancel TSO-C129a, given the eventual obsolescence of TSO-C129a equipment, and the lack of industry interest in new TSO-C129a product designs.

Issued in Washington, DC, on August 1, 2011.

Susan J.M. Cabler,

Assistant Manager, Aircraft Engineering Division, Aircraft Certification Service.

[FR Doc. 2011-20812 Filed 8-15-11; 8:45 am]

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