They are always advertising!
There are a number of very apparent reasons SERCO and Baghdad are always advertising!
SERCO's market share of ANS continues to shrink in the Middle East despite all efforts they make to hold onto what they've had.
They have an extremely troubling management/human resources problem within SERCO. The number of front line and HQ managers that have come and gone within SERCO is the past 5 years speaks to the internal troubles of the company.
The woman running the HR in Dubai for ATCO's in SERCO ME has no clue about proper recruiting and hiring practises and until she is gone they will continue to be advertising for applicants.
The Baghdad Contract in particular doesn't compensate enough for the increased risks associated with this location and instead relies on those whose last resort it is to apply for this posting. There isn't enough time off so that you can travel out of the base for R&R between cycles.
My suggestion is wait until another ANS provider is granted the contract for Baghdad and operates it in an entirely different way.