Algorithm 01
Quaternion Gyroscope Integration
Gyroscope ω rates integrated as a unit quaternion at 60Hz. Avoids gimbal lock entirely. Full mathematical detail in the app.
Algorithm 02
Mahony-Style AHRS Drift Correction
Accelerometer gravity vector cross-product used to correct quaternion drift. Proportional-integral feedback keeps long-haul accuracy without GPS.
Algorithm 03
Yaw-Immune Bank Angle Extraction
World-right vector projected through the attitude quaternion. Horizontal magnitude denominator makes bank completely immune to heading rotation.
Algorithm 04
Tilt-Blend Pitch / Bank Fusion
Quaternion attitude blended with raw accelerometer tilt as a function of cosine-tilt. Handles any phone mounting angle without configuration.
Algorithm 05
Turbulence RMS Classifier
High-pass filtered accelerometer RMS mapped to FAA severity thresholds. Per-aircraft gross weight normalisation — a 747 damps far more than an E175.
Algorithm 06
ISA Pressure-Altitude Conversion
Standard atmosphere formula converts barometric pressure to pressure altitude. QNH correction gives indicated altitude. All running from the phone's baro sensor.
Algorithm 07
Three-Phase Cabin Pressurisation Model
Unpressurised → ramp → cruise differential model estimates true plane altitude from cabin pressure. Aircraft-specific max differential applied per type.
Algorithm 08
Auto Takeoff / Landing Detection
Cabin altitude rate-of-change triggers automatic flight phase transitions. No GPS needed — baro alone detects pressurisation start.
Algorithm 09
Great-Circle Route Progress
Haversine formula computes bearing and distance between departure and arrival. GPS position projected onto the great-circle track for real progress.
Algorithm 10
GPS-Off Dead Reckoning
In aeroplane mode, aircraft cruise TAS and elapsed time compute estimated position along the great-circle. Closest airport scoring still works.
Algorithm 11
Jet Stream ETA Correction
Ground speed estimated from GPS track speed. Deviation from cruise TAS attributed to headwind/tailwind and applied to remaining ETA.
Algorithm 12
Divert Airport Heading-Weighted Score
3,500+ airport database scored by distance and heading alignment. Reachability score updated every 30 seconds using current GPS bearing.
Algorithm 13
Per-Axis Gyro Scale Calibration
360° rotation integration measures actual vs expected angular change per axis. Scale factors stored permanently and applied at sensor read time.
Full Detail in the App
The complete mathematical derivations, source equations, and implementation notes are documented inside GeekFlight itself — in the Technical Reference section.
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