Helicopter navigation experienced magnetic interference

What happened?

On a normal (passenger) crew change flight in an AW169 helicopter, crew noticed a “1-2 AHRS FAIL” caution displayed in the crew alert system shortly after departure from the offshore installation.  With this caution message, electronic helicopter heading information was completely lost.

Image: Wikipedia

What went wrong?  What were the causes?

After disembarking, the passengers were asked if they had any ferrous or magnetic parts in their luggage, which was initially denied.  After becoming aware of certain products possibly containing magnets, one of the passengers realized and admitted that he had two medium size stereo speakers in his luggage.

The cause of the instrument failure was found to be due to the presence of magnetic elements (speakers) in the luggage hold.

In bad weather conditions, navigation errors due to loss of orientation could have resulted in a far more serious outcome.

What actions were taken?

  • The helicopter equipment involved in the occurrence was checked for damages and for correct function. No damage nor discrepancies were found; the helicopter was released for service;
  • Check-in personnel now inform passengers that stereo speakers are not permitted on board helicopters;
  • Check-in personnel make random checks of passengers’ luggage (as approved by customer/passenger) for items not to be transported onboard helicopters;

What lessons were learned?

  • There is poor awareness amongst helicopter passengers as to what could constitute hazardous goods; information on such potentially hazardous items needs to be made more readily available;
  • Offshore facilities (helicopter departure lounges) are not displaying adequate lists or images of items which are not permitted on board helicopters; this needs to be addressed and rectified.