When an airline purchases a new passenger jet, they often have a choice of engines (from different manufacturers). Why is this?
I would expect that one of the engine options is "best" and that all customers would buy that option. Thus it wouldn't be worthwhile to certify and offer the other (unwanted) options. Evidently this is not the case, so the question is why.
I can think of two possible reasons for this:
- Different customers may have different requirements (e.g. shorthaul versus longhaul routes, operating in hot or cold environments) and different engine options have differing performance (e.g. better cruise efficiency versus climb efficiency or better performance in hot/cold temperatures). But I can't imagine that the requirements would be significantly different and, if they were very different, they would buy a totally different plane, not just a different engine.
- Business/legal considerations: Perhaps airlines have contracts with engine manufacturers separate from aircraft manufacturers. e.g. British Airways may have a special relationship with Rolls Royce (possibly due to trade tariffs). But, again, I would imagine that airlines would always seek the most efficient engines, rather than signing such contracts.
Are either (or both) of these reasons right or is there a totally different reason?