A union representing Cathay Pacific's cabin crew has withdrawn an application to stage a rally on Wednesday after the company declined permission for the event to take place on its premises.

The Cathay Pacific Airways Flight Attendants Union (FAU) earlier filed an application to police to hold a gathering outside the airline's headquarters to demand better working conditions.

"The company does not consent to the proposed assembly taking place on its premises, FAU will not be able to obtain the letter of no objection from the police authority," the union said in a statement on Tuesday.

However, it said it will press ahead with a work-to-rule campaign from Thursday to seek better roster arrangements and longer layovers.

Writing in an open letter, the union called for understanding from Hongkongers and its customers.

"From tremendous redundancy, huge permanent pay cut, outport allowance cut, manpower cut but increased workload, reduced rest time to reduced outport layover period, we have reached the edge," it wrote.

"These cuts also cause impact on customer safety and prolonged inflight service, which undoubtedly affect the overall experience of our valued passengers. Cathay Pacific claimed all the flight operations remain normal; however, this is not the truth."

The union said cabin crew members were left helpless and frustrated after one less staff was scheduled to be on board each flight since last year, adding that more than 30 flights departed without a full crew on January 1 this year.

It noted that flights between Hong Kong and Japan were the most affected, with only four crew members – instead of the original seven – working in the premium economy and economy class to serve 288 passengers.

"We are disheartened to see any impact on your travel plans; however, our fundamental call for treating us in a humane way has fallen on deaf ears. We have no choice but to implement work-to-rule starting from 19 January," the union said.

A passenger who set off for Thailand on Tuesday morning, Yvonne, told RTHK she is concerned the union's action will affect her return flight.

"I worry I cannot [return] on time...I hope everything is fine, and don't make trouble to travellers," she said.

Another passenger, Veronica, said employees can negotiate with their bosses for better working conditions, but what customers truly want is good service.

"The manpower is limited, I know that. But during the flight, our activities are also limited, because we all do not run [around], and also we just stay [at our seats] as much as we can. [Cabin crew] just serve the meal, then we can care for ourselves. That is good enough," she said.

Cathay, for its part, said it has been communicating directly with its cabin crew and had implemented changes to its rosters from this month.

The carrier told passengers that services will continue as scheduled.