NTSB CAROL · Event
Event ATL91IA094
Aircraft involved
Probable cause & findings
THE CAPTAIN'S FAILURE TO MAINTAIN A PROPER GLIDE PATH AFTER DISCONNECTION OF THE AUTOPILOT DURING THE FINAL APPROACH. FACTORS IN THIS ACCIDENT WERE: THE CAPTAIN'S FAILURE TO FOLLOW COMPANY PROCEDURES FOR CATEGORY II APPROACHES, THE FIRST OFFICER'S FAILURE TO ADEQUATELY MONITOR THE APPROACH DURING THE FINAL PHASE, PRIOR TO TOUCHDOWN, AND THE LOW VISIBILITY AT THE TIME OF THE ACCIDENT.
Factual narrative
FLT 1206 WAS ON FINAL FOR A CAT II ILS RWY 2L APCH. THE LAST RPRTD RVR PRIOR TO LANDING WAS 700 FT, & 1200 FT RVR WAS RPRTD AS THE FLT CROSSED THE OUTER MARKER. MINIMUMS FOR THE APCH WERE 1200 FT RVR. ON SHORT FINAL, THE CAPT SAW APCH LIGHTS & DISCONNECTED THE AUTOPILOT AS THE ACFT DSCNDD BELOW 200 FT AGL. THE ACFT TOUCHED DOWN 408 FT SHORT OF THE RWY THRESHOLD, DAMAGING THE APCH LIGHTING SYS & THE ACFT. DFDR READOUT REVEALED THE ACFT RATE OF DSCNT INCREASED FROM 720 FPM TO 1400 FPM AFTER THE AUTOPILOT WAS DISCONNECTED, WHILE AIRSPEED REMAINED CONSTANT. INSPN OF THE ACFT NAV EQUIP & ARPT NAV AIDS REVEALED NO EVIDENCE OF MALFUNCTION. ALTHOUGH THE CAPT STATED THAT HE HAD THE APCH LIGHTS VISUALLY, HE WAS UNAWARE THE ACFT HAD LANDED SHORT. THE FLT ENGINEER STATED HE FELT THE ACFT HAD INDEED LANDED SHORT. THE CAPT DISCONNECTED THE AUTOPILOT AT ABOUT 200 FEET AGL, ALTHOUGH COMPANY PROCEDURES REQUIRED USE OF THE AUTOPILOT DOWN TO DECISION HEIGHT (100 FT AGL). Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_1991_ATL91IA094.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (autopilot). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- arXiv 2025 · arXiv preprint
ROSflight 2.0: Lean ROS 2-Based Autopilot for Unmanned Aerial Vehicles
ROSflight is a lean, open-source autopilot ecosystem for unmanned aerial vehicles (UAVs). Designed by researchers for researchers, it is built to lower the barrier to entry to UAV research and acceler…
- arXiv 2025 · arXiv preprint
ROSplane 2.0: A Fixed-Wing Autopilot for Research
Unmanned aerial vehicle (UAV) research requires the integration of cutting-edge technology into existing autopilot frameworks.
- arXiv 2024 · arXiv preprint
A Data-Driven Autopilot for Fixed-Wing Aircraft Based on Model Predictive Control
Autopilots for fixed-wing aircraft are typically designed based on linearized aerodynamic models consisting of stability and control derivatives obtained from wind-tunnel testing.
- arXiv 2022 · arXiv preprint
Experimental Flight Testing of a Fault-Tolerant Adaptive Autopilot for Fixed-Wing Aircraft
This paper presents an adaptive autopilot for fixed-wing aircraft and compares its performance with a fixed-gain autopilot.
- arXiv 2021 · arXiv preprint
An Adaptive Digital Autopilot for Fixed-Wing Aircraft with Actuator Faults
This paper develops an adaptive digital autopilot for a fixed-wing aircraft and compares its performance with a fixed-gain autopilot.
- arXiv 2020 · arXiv preprint
Reinforcement Learning for Robust Missile Autopilot Design
Designing missiles' autopilot controllers has been a complex task, given the extensive flight envelope and the nonlinear flight dynamics.
Browse the full corpus — academia portal ↗