Your company is living in fairyland, applying for work visa extensions just because someone has experience within an airline. Until they are granted
PR status or obtain a Hong Kong passport they are just contract workers on a two year rolling basis.
Most immigration departments take the necessary steps to protect their industries and now is the time for Hong Kong to protect the local workforce and follow the policy and procedures presented in their documentation.
To quote a few government documents online ;
"Promoting the employment of local workers and protecting the rights and benefits of employees top the agenda for the Government."
"The Hong Kong government strongly advocates that employers must give first preference to the local workforce for filling job vacancies."
"long-established Government policy that priority in employment should be given to the local workforce and importation of foreign workers should only be allowed when there is proven manpower shortage in specific trades that cannot be filled by local workers."
"While giving employment priority to local workers, we will stay vigilant and explore with stakeholders the pros and cons of increasing imported labour on an appropriate and limited scale to support our development as a high value-added and diversified economy."
The immigration department and Legco will continue to be lobbied until there is a much higher percentage of locally qualified crew re-employed in Hong Kong.
Best of luck.