Capt PPRuNe,
Your 250 nm limit appears to be a company rule only. I can take off as long as I have an alternate within 2 hours flying time at one-engine-out speed (I have 4 engines). For twin-engined a/c within the company the limit is 60 mins. Our companies agree on the other conditions. Assuming then that the question refers to a 4-engined a/c, it is not as far-fetched as it may seem.