What this profile covers
Normal, abnormal, runaway, mistrim, or unexpected trim behavior and its effect on control forces, attitude, speed, and system response.
Why it matters
Safe control depends on a shared understanding of aircraft state, selected and active modes, system limits, and the intended flight path. For trim system events, useful analysis connects the immediate event with exposure, defenses, recurrence, and the wider operating system rather than treating one observation as a final conclusion.
Manual control, flight-guidance modes, automation behavior, protections, energy, and upset prevention.
Understand the subject before interpreting a signal.
In plain language, this profile examines normal, abnormal, runaway, mistrim, or unexpected trim behavior and its effect on control forces, attitude, speed, and system response.
Build a multi-source picture
- Selected, armed, active, and degraded mode states
- Commands compared with aircraft response
- Crew reports, procedures, and training context
- Software standard, system status, and maintenance evidence
Timing, relationships, and recurrence
Relevant recorded context may include radio altitude, vertical speed, pitch attitude, engine thrust, ground spoiler position. Use validated mappings and examine signal relationships over the applicable flight phase.
Do not turn an observation into a conclusion
Automation state data can show what the system recorded, but not the crew's intention, understanding, or causal reasoning without corroborating evidence.
Keep controlling material visible
Apply the current approved manuals, procedures, authority requirements, investigation evidence, and validated organizational definitions for any operational decision.
Radio altitude
Height derived from radio altimetry, normally representing the distance from the aircraft to terrain directly below within the system's operating range.
Open parameter guide ↗ft/min or m/sVertical speed
The aircraft's vertical rate. Different recorded sources and smoothing can produce materially different values, especially during flare and touchdown.
Open parameter guide ↗degPitch attitude
Aircraft body attitude above or below the local horizontal reference.
Open parameter guide ↗% / ratio / aircraft-specificEngine thrust
One or more recorded measures of commanded or produced propulsion; the correct signal depends on engine and aircraft type.
Open parameter guide ↗deg or discreteGround spoiler position
Position or deployment state of panels used to reduce lift and increase wheel loading after touchdown.
Open parameter guide ↗discreteLanding gear status
Command, position, lock, and ground-sensing states associated with the landing gear; these are separate signals with different meanings.
Open parameter guide ↗From a broad topic to a defensible safety review.
Define
State what trim system events means for the aircraft, operation, authority, and organization in scope.
Verify
Confirm the provenance, quality, timing, units, completeness, and limitations of every data source used.
Describe
Reconstruct what happened and quantify relevant exposure before discussing causes or corrective action.
Corroborate
Compare flight data with reports, operational context, technical evidence, and authoritative source material.
Test barriers
Identify which preventive, recovery, and consequence-mitigation controls should have worked and how their performance can be measured.
Assure
Assign proportionate action and verify whether the control and safety performance improve without harmful unintended effects.
Questions before conclusions
- Q1
How is trim system events defined for the aircraft, operation, authority, and organization being reviewed?
- Q2
Which precursors, recorded signals, reports, and external data would confirm the event and describe its context?
- Q3
Which preventive, recovery, and consequence-reduction barriers should work, and where could they weaken?
- Q4
What does recurrence, exposure, severity potential, or change over time show before choosing a safety action?
4 connected event profiles
These are terminology and family connections for exploration—not claims that FDM alone can determine the topic.
Takeoff trim setting deviation
Pitch-trim position is outside the applicable operator-defined band for the planned takeoff condition.
Open FDM profile ↗FDM-039 · CruiseCabin altitude warning
A recorded cabin-altitude warning or high cabin-altitude condition occurs during pressurised flight.
Open FDM profile ↗FDM-059 · Approach stabilityApproach configuration incomplete at gate
Gear, flap, slat, spoiler-arm, or other required landing configuration is incomplete at a validated approach gate.
Open FDM profile ↗FDM-119 · Systems & warningsAnti-ice configuration mismatch
Anti-ice or de-ice system state differs from the validated environmental, phase, or procedure context.
Open FDM profile ↗Go deeper into the closest ASIP research guides.
Unstable Approach
Recognize when path, speed, configuration, power, or crew readiness has moved outside applicable stabilized-approach criteria.
Open intelligence brief ↗Aircraft SystemsFlight-Deck Automation
Use mode awareness, active monitoring, and aircraft-response verification to keep automation aligned with crew intent.
Open intelligence brief ↗Human FactorsHuman Factors and Fatigue
Study how workload, fatigue, expectation, communication, interface design, and organizational conditions shape performance.
Open intelligence brief ↗12 useful starting points
Original ASIP summaries lead to publisher pages. ASIP does not copy or host the reports.
A330-300 Trimmable Horizontal Stabilizer Damage
Official Airbus Safety First material indexed for aviation safety. Open the publisher source for the complete document, scope, and current status.
Open official sourceAnnex 19 — Safety Management, Third Edition
Annex 19 consolidates ICAO safety-management provisions, including State safety responsibilities, SMS, safety-data collection and processing, and the protection and sharing of safety information.
Open official sourceAnnual Safety Review 2025
EASA's review uses occurrence and accident information to describe performance across aviation domains and to support the European safety-risk-management process.
Open official sourceStatistical Summary of Commercial Jet Airplane Accidents, 1959–2024
Boeing's 56th annual statistical summary organizes commercial-jet accident data using stated definitions and the CAST/ICAO occurrence taxonomy.
Open official sourceIATA Annual Safety Report — 2024
IATA's 61st annual report provides an interactive, method-defined view of commercial aviation accident performance and contributing-factor classifications.
Open official sourceAC 120-92D — Safety Management Systems for Aviation Service Providers
FAA guidance explains performance-based, scalable approaches to integrating safety policy, risk management, assurance, and promotion into aviation organizations.
Open official sourceAC 91-79B — Aircraft Landing Performance and Runway Excursion Mitigation
This FAA circular brings together landing-performance planning, time-of-arrival assessment, RCAM information, and operational practices for reducing runway-excursion risk.
Open official sourceSafety Alert SA-077 — Stabilized Approaches Lead to Safe Landings
The NTSB alert highlights the need to establish and maintain a stabilized approach and to go around when an approach falls outside applicable criteria.
Open official sourceHigh Load Event Reporting
The Airbus Safety First article explains why a pilot report remains central after a suspected high-load event and how recorded reports and analysis tools can support the applicable maintenance process.
Open official sourceSafety Management Manual (Doc 9859), Fourth Edition
ICAO's fourth-edition manual explains how safety data, risk management, assurance, culture, and governance work together in State and service-provider safety management.
Open official sourceGo-Around Decision-Making and Execution Project — Final Report
The Flight Safety Foundation project examines go-around policy compliance, decision biases, operational pressures, and the risks that also need to be managed during go-around execution.
Open official sourceCAP 739 — Flight Data Monitoring, Second Edition
CAP 739 presents FDM as the systematic, proactive use of routine digital flight data within a non-punitive, just safety culture.
Open official sourceCommon Taxonomy Team
International work on common aviation occurrence categories and definitions for consistent reporting and analysis.
Open referenceSafety Risk Management
European safety-risk process connecting data, safety issues, risk portfolios, priorities, and safety action.
Open referenceAnnual programmes and reports
Annual safety reviews and risk portfolios used to identify key risk areas, safety issues, and emerging issues.
Open referenceEuropean Plan for Aviation Safety 2025
A broad evidence-based portfolio showing the scale and connected nature of current aviation safety issues.
Open referenceOperational issues index
A practical discovery index for operational safety subjects; official authority and manufacturer sources remain controlling where applicable.
Open reference