Originally Posted by
ba_cityflyer
Presumably the purpose such a rule is to deter employees from preferring an airline which may not be the most cost-effective or direct option, for a given trip. Though this is solved simply by having a rule prohibiting this, or by having a TA book everything.
Our travel policy does actually spell this very exactly out. I.e. we are allowed to select a flight based on alliance, but it has to be inside of the same price as other flights and can not cause the flight time to be much larger.