FDM-008Ground & taxi

Asymmetric thrust during taxi

A sustained difference between left and right propulsion parameters appears during taxi movement.

4Signal groups
1Flight phases
14Safety topics
12Reading links

What the profile screens for

A sustained difference between left and right propulsion parameters appears during taxi movement.

Why it matters

The pattern may be deliberate steering technique, system behaviour, or a propulsion asymmetry that needs context and validation.

Flight-phase contextTaxi
Risk lensesRunway excursion / abnormal runway contactOperational procedure deviation

Build the event around relationships—not one number.

01 · Gate

Define the operating context

Identify the taxi state, aircraft configuration, location, and any required external data before applying logic.

02 · Detect

Screen the signal relationship

Use validated combinations of left engine thrust, right engine thrust, steering angle; avoid treating one isolated value as the whole event.

03 · Validate

Confirm it is a genuine event

Check polarity, units, source, recording rate, dropouts, air/ground logic, persistence, and false-positive mechanisms.

04 · Contextualise

Connect data to the safety question

Review procedures, reports, weather, airport and traffic context, exposure, recurrence, and the strength of the related barriers.

Recorded signals that may help explain the event.

left engine thrustright engine thruststeering anglegroundspeed

Questions before conclusions

  1. Q1

    Are left engine thrust, right engine thrust, steering angle valid, correctly decoded, time-aligned, and sampled well enough for this event?

  2. Q2

    What changed immediately before, during, and after the asymmetric thrust during taxi indication?

  3. Q3

    How do aircraft configuration, weather, airport geometry, automation state, and crew reports change the interpretation?

  4. Q4

    Which current flight manual, SOP, maintenance, or operator event definition controls the final conclusion?

Safety topics that broaden the event review.

Topic atlas12 operational connections
SAT-003 · Runway safety

Runway confusion

Misidentification of runway, taxiway, intersection, direction, or airport geometry before a takeoff, landing, crossing, or line-up action.

Open topic profile ↗
SAT-006 · Runway safety

Runway condition code

Use and cross-checking of runway condition assessment codes, contaminant descriptions, temperature, and reported braking information.

Open topic profile ↗
SAT-007 · Runway safety

Runway occupancy

Time and movement patterns while entering, crossing, lining up, landing, vacating, or otherwise occupying an active runway.

Open topic profile ↗
SAT-008 · Runway safety

Runway lighting and markings

The role, condition, interpretation, and operational limitations of runway, taxiway, stop-bar, centreline, and approach visual aids.

Open topic profile ↗
SAT-009 · Runway safety

Runway hotspots

Airport locations with complex geometry or a history of confusion, incursion, excursion, or surface-navigation difficulty requiring heightened awareness.

Open topic profile ↗
SAT-092 · Ground operations & maintenance

Aircraft towing

Control of route, speed, clearance, steering, braking, communication, lighting, wing walkers, and equipment during aircraft towing.

Open topic profile ↗
SAT-093 · Ground operations & maintenance

Ramp collision

Contact risk among aircraft, vehicles, equipment, structures, or people in congested ramp and stand environments.

Open topic profile ↗
SAT-094 · Ground operations & maintenance

Ground damage

Aircraft damage during parking, movement, servicing, loading, maintenance, or weather exposure, including detection and reporting barriers.

Open topic profile ↗
SAT-095 · Ground operations & maintenance

Foreign object debris

Objects on operational surfaces or in work areas that can damage aircraft, engines, tyres, systems, vehicles, or people.

Open topic profile ↗
SAT-096 · Ground operations & maintenance

Aircraft de-icing

Inspection, fluid selection and application, holdover assessment, contamination checks, communication, sequencing, and clean-aircraft assurance.

Open topic profile ↗
SAT-097 · Ground operations & maintenance

Aircraft fueling

Fuel type, quantity, quality, bonding, pressure, spill, fire, communication, passenger, and vehicle risk during aircraft refueling or defueling.

Open topic profile ↗
SAT-099 · Ground operations & maintenance

Maintenance error

Unintended maintenance action or omission shaped by task design, data, tools, access, handover, pressure, supervision, and verification.

Open topic profile ↗
Deep briefs2 detailed research guides

12 useful starting points

Terminology and topic relationships select these links; the publisher source remains authoritative.

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IATA Annual Safety Report — 2024

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U.S. Federal Aviation AdministrationRelated safety-topic match

AC 91-79B — Aircraft Landing Performance and Runway Excursion Mitigation

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EASA

Easy Access Rules for Air Operations — ORO.AOC.130

Official source
EASA / EOFDM

European Operators Flight Data Monitoring forum

Official source
FAA

AC 120-82 — Flight Operational Quality Assurance

Official source
UK CAA

CAP 739 — Flight Data Monitoring

Official source
ICAO

Doc 10000 — Manual on Flight Data Analysis Programmes

Official source