A Vermont woman whose bizarre behavior caused a security scare on a trans-Atlantic flight in 2006 is expected to plead insanity at her trial in Boston.

Authorities said Catherine Mayo urinated on the floor of the cabin and made statements the pilot and crew believed were references to Al Qaeda and the Sept. 11 terrorist attacks.

She was arrested in August of 2006, when the London-to-Washington flight was diverted to Boston, and charged with interfering with a flight crew.

Mayo is scheduled to appear in U.S. District Court Monday for a trial before Judge Nancy Gertner.

Prosecutors have said they believe Mayo, who lived in Braintree, Vt., at the time, was mentally ill and not linked to any terrorist group.