Safety & tech

Hover drift and toilet bowl

Aircraft drifts, flies in circles or cannot hold position. Common on: DJI Mini/Mavic/Air, Autel, FPV with GPS module (BN-220, M10), INAV GPS rescue.

A2STS editorial12 min read

Contents

Overview

Aircraft drifts, flies in circles or cannot hold position.

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

Symptoms

Typical "Hover drift and toilet bowl" signs in flight, app or OSD:

  • GPS mode — slow circling (toilet bowl)
  • ATTI mode — strong drift in wind
  • Position hold drifts away from home
  • Log satellite count, HDOP and RTH status before arming.

Common causes

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

  • GPS multipath between buildings
  • Misaligned compass — wrong heading correction
  • Wind exceeds aircraft capability in ATTI
  • INAV/Betaflight GPS Rescue wrong P gains

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.

  • Fly in open area — check if issue disappears.
  • Recalibrate compass and IMU.
  • DJI: compass + IMU + vision cal; update firmware.
  • FPV INAV: check mag alignment and GPS baud rate.

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 arm GPS mode without full lock
  • Respect wind limits per spec

Frequently asked questions

Is it safe to fly with "Hover drift and toilet bowl"?
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 “Hover drift and toilet bowl” cases — 15–45 min on the ground. Complex ones (firmware, hardware) may need 1–2 h and service.
Must I register repair with the NAA?
No mandatory repair registration, but a maintenance log is recommended for commercial operations.

Authority & sources

A2STS Editorial · Reviewed by: EASA UAS syllabus aligned