Sam,
Search the Cove and you’ll find a lot of advice, for example:
Implementation of QMS
Even if not for an airline, the principles are the same. Start by studying how your airline already works as a system to fulfill customer needs.
And here is a document you may find valuable:
https://skybrary.aero/sites/default/files/bookshelf/4620.pdf. Airlines already tend to operate above and beyond the requirements of ISO 9001 so you’ll not have that much to do.
John