It is prohibited for the company to contact employees who were away from home and off duty, except in exceptional circumstances, including if there had been a flight delay or cancellation.
Mount Cook already provides the staff with accommodation, transport to and from the airport and pays overnight and meal allowances.
Appearing for the union Peter Cranney argued the staff away from home overnight were working and were entitled to pay under the Minimum Wage Act.
He claimed there were limitations to an employee's ability to pursue personal activities and while off duty they could not take up secondary employment.
Kevin Thompson, appearing for Mount Cook, acknowledged it could be an inconvenience for staff to stay away from home but it didn't reach the constraints required to be determined work.
Thompson also accepted prohibition on consuming alcohol, 10 hours before the rostered start time, was a restriction but argued it applied to all cabin crew regardless of their location.
The Employment Court maintained three factors were used to assess the definition of work; constraints placed on the employee, responsibilities of the employee and the benefit to the employer.
A case involving the determination of whether a community service worker was working during a sleepover at a community home was used, along with other case law, to identify the criteria.
The worker could not leave the house without permission, had to be available to be woken if needed by a resident, could not drink alcohol and could not have visitors without permission.
Judge Smith accepted staff might be inconvenienced but unlike in the example case there was absolutely nothing required of them.
"What is clear is that after one duty day ends and before the next one begins the employees are free to do as they please.
"The fact that the employees are away from home is not enough by itself to amount to a constraint of the sort that was persuasive in those earlier cases."
Judge Smith was unable to reach a determination about the other dispute which related to whether the salary paid to part-time cabin crew in the collective agreement complied with Minimum Wage Orders.
There was a benefit to Mount Cook in having staff stay overnight, Judge Smith conceded but it wasn't enough to tip the scales.
"When all of these assessment factors are weighed up the absence of any constraints on the employees, in combination with them having no responsibilities or duties to perform, are extremely persuasive."
Judge Smith ruled part-time cabin crew who were away from home overnight were not working within the meaning of the Act.
He said it would not be appropriate to make a decision whether the salary paid to part-time cabin crew in the collective agreement complied with Minimum Wage Orders from the information provided, and invited further submissions from both parties.
