Summary
On November 06, 1990, a Aerospatiale ATR-42-300 (N972NA) was involved in an incident near San Juan, PR. All 44 people aboard were uninjured.
The National Transportation Safety Board determined the probable cause of this incident to be: THE IMPROPER USE OF AILERON TRIM AND THE IMPROPER PREPARATION FOR AUTO PILOT DISCONNECT BY THE FLIGHT CREW COMBINED WITH EXCESSIVE FORCES APPLIED BY THE AILERON TRIM SYSTEM RESULTING IN A DEPARTURE FROM CONTROLLED FLIGHT. CONTRIBUTING FACTORS TO THE INCIDENT WERE INADEQUATE AND MISLEADING AUTOPILOT WARNINGS, LACK OF CONSPICUITY OF THE AILERON TRIM INDICATOR, LACK OF FAA REGULATION GOVERNING CONTROL AUTHORITY IN MISTRIM CONDITIONS, AUTOPILOT SYSTEM MASKING OF MISTRIM CONDITIONS, AND THE LACK OF FAA REQUIREMENT FOR RECURRENT PILOT TRAINING IN AUTOPILOT USE.
This incident is documented in NTSB report MIA91IA022. AviatorDB cross-references NTSB investigation data with FAA registry records to provide comprehensive safety information for aircraft N972NA.
Accident Details
Probable Cause and Findings
THE IMPROPER USE OF AILERON TRIM AND THE IMPROPER PREPARATION FOR AUTO PILOT DISCONNECT BY THE FLIGHT CREW COMBINED WITH EXCESSIVE FORCES APPLIED BY THE AILERON TRIM SYSTEM RESULTING IN A DEPARTURE FROM CONTROLLED FLIGHT. CONTRIBUTING FACTORS TO THE INCIDENT WERE INADEQUATE AND MISLEADING AUTOPILOT WARNINGS, LACK OF CONSPICUITY OF THE AILERON TRIM INDICATOR, LACK OF FAA REGULATION GOVERNING CONTROL AUTHORITY IN MISTRIM CONDITIONS, AUTOPILOT SYSTEM MASKING OF MISTRIM CONDITIONS, AND THE LACK OF FAA REQUIREMENT FOR RECURRENT PILOT TRAINING IN AUTOPILOT USE.
Aircraft Information
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# MIA91IA022