# Airworthiness Directives; Trimble or FreeFlight Systems 2101 I/O Approach Plus Global Positioning System (GPS) Navigation Systems
> **Rule** · Final rule. · Published 2009-03-16 · Effective 2009-04-20 · 74 FR 11003
## Document
- **Document number:** E9-4942
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 74 FR 11003
- **Publication date:** 2009-03-16
- **Effective date:** 2009-04-20
- **FAA docket:** Docket No. FAA-2007-28689
## Abstract

This amendment adopts a new airworthiness directive (AD) for the Trimble or FreeFlight Systems 2101 I/O Approach Plus global positioning system (GPS) navigation system (2101 I/O Approach Plus system) that requires a software upgrade for this system. This amendment is prompted by an incident that led to the discovery of several annunciation errors with the 2101 I/O Approach Plus system. The actions specified by this AD are intended to prevent a pilot from making an unsafe decision based on erroneous information provided by the 2101 I/O Approach Plus system, which could result in loss of control of the aircraft.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2009/03/16/E9-4942/airworthiness-directives-trimble-or-freeflight-systems-2101-io-approach-plus-global-positioning)
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