An employee who persistently, wilfully, and deliberately refuses to comply with lawful and reasonable instructions from their employer over an extended period, despite multiple opportunities to comply, is guilty of gross insubordination. When reviewing arbitration awards under section 145 of the LRA, a court applies an outcome-based test and will not interfere unless the decision falls outside the band of reasonableness. An applicant challenging such an award must demonstrate that any alleged defects in the arbitrator's reasoning had a distorting effect on the ultimate outcome. Personal circumstances, clean disciplinary record, and long service, while mitigating factors, may be outweighed by the seriousness of the misconduct, the employee's seniority, the nature of the position, operational considerations, and failure to show remorse.