AD Amdt-39-11473
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Various | Transport Category | Airworthiness Directives; Various Transport Category Airplanes Equipped With Mode ``C'' Transponder(s) With Single Gillham Code Altitude Input |
Unsafe Condition
Reports indicate that during level flight, TCAS II issued false advisories due to inaccurate airplane altitude reporting from Mode 'C' transponders with single Gillham code altitude input, potentially causing flightcrew deviation from assigned flight paths and increasing risk of mid-air collision.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect and test the Mode 'C' transponder(s), air data computer, and certain wiring connections for discrepancies. Perform corrective actions if necessary.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Revised compliance times as specified in the new amendment.
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Affected Aircraft
Various transport category airplanes equipped with certain Mode 'C' transponders with single Gillham code altitude input.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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