# Yaw Estimate Error

Source: https://forum.modalai.com/topic/5033/yaw-estimate-error
Category: Development Drones (https://forum.modalai.com/category/44/development-drones)
Tags: starling
Posted: 2026-02-04 23:08:15 UTC by Nitin Varma Vegesna
Replies: 2 · Views: 454

## Nitin Varma Vegesna · 2026-02-04 23:08:15 UTC

Hello,

In /etc/modalai/voxl-px4.conf set GPS to NONE. Then set the PX4 parameters SYS_HAS_GPS, and SYS_HAS_MAG to 0. Set EKF2_MAG_TYPE to None. Set EKF2_GPS_CTRL to 0. This is when my GPS was broken. 

I was getting Preflight Fail: heading estimate not stable and Preflight Fail: Yaw estimate error

How could I fix the error? Is there any calibration or anything else that needs to be done?  I was looking at QGC and yaw seemed to move smoothly when i yawed so I don't know what the issue is. /mavros/local_position/odom seems to be properly providing the drone's pose as well, at least the position and yaw.

## Reply by lhermosillo · 2026-02-05 01:12:36 UTC

@Nitin-Varma-Vegesna Are you using EKF2_EV_CTRL to supplement the GPS denial?

## Reply by Nitin Varma Vegesna · 2026-02-06 06:06:47 UTC (in reply to lhermosillo)

@lhermosillo It was 15 with/without the GPS.