Compass error

Overview

Magnetometer error blocks GPS and stable flight. Calibration and interference removal.

Common on: DJI Mini/Mavic/Air, Autel, FPV with GPS module (BN-220, M10), INAV GPS rescue.

Symptoms

Typical "Compass error" signs in flight, app or OSD:

• Compass error in app — red icon
• GPS disabled until calibration completes
• Yaw drift — aircraft rotates without input
• RTH in wrong direction
• Unexpected ATTI mode
• Log satellite count, HDOP and RTH status before arming.

Common causes

Before replacing parts, rule out software, mechanical and environmental causes:

• Metal platforms — car roof, rebar, metal roofing
• Magnetic objects — speakers, tools, phone on aircraft
• Damaged magnetometer after crash
• Transport near magnets (loudspeakers, tools)
• Cables around GPS module — EMI

Tools needed

Prepare before diagnostics — saves time in the field:

• Open area away from metal
• DJI Fly / Pilot or Betaflight Configurator
• Flight log export

Step-by-step fix

Work safely: battery off when working on ESC/motors; props removed; after repair — VLOS test flight.

• 1. Move to open area, 5+ m from vehicles and metal.
• 2. DJI: calibration — horizontal 360° + vertical rotation per animation.
• 3. Reboot aircraft and RC; repeat away from interference.
• 4. FPV: check mag alignment, FC orientation and GPS module distance.
• 5. If error persists — replace GPS/compass module or service.

Additional diagnostics

Log satellite count, HDOP and RTH status before arming.

Compare behaviour indoors vs outdoors — confirms GPS limitation.

FPV: Betaflight GPS tab — baud 57600/115200, mag alignment.

When to contact service

If any of the following apply — do not fly and contact authorised service:

• GPS still shows no satellites after calibration and firmware update.
• After crash — physical GPS antenna or cable damage.
• Compass wrong even in open field — service required.

Prevention

Prevention reduces failure risk and supports EASA Open / VLOS compliance:

• Do not store on car roof
• Dedicated carry case without magnets
• Compass check ritual after transport

Frequently asked questions

Is it safe to fly with "Compass error"?

No if the fault affects navigation, power, ESC or link. Fix on the ground first, then conduct a VLOS test flight in open area.

How long does diagnosis take?

Most “Compass error” cases — 15–45 min on the ground. Complex ones (firmware, hardware) may need 1–2 h and service.

Can I fly without compass calibration?

DJI and most GPS drones block arming without compass. FPV with GPS module needs magnetometer for correct heading.