10 years ago an EK recruitment manager told me it cost a minimum of 2 million AED from recruitment to LHS...all the recruitment costs, costs of bringing in supporting the family, and training from RHS to LHS. Nowadays it would be 50% more than that at least.
Factor in say 3.5 million AED into the monthly pay difference between a new Captain and a 15 year Captain, and it's clearly better to retain an experienced Captain until retirement than it is to wave him goodbye to save at most 15,000AED a month. On that simple equation, it would take 19 years to recover the replacement costs of the experienced Captain with a new guy in the LHS (ex DE FO) and maybe 40% of that time for a DEC