Most operators would plan routes to stay within an acceptable range of adequate airfield in case of emergencies. The most crucial emergencies dealing with degraded aircraft performance. So far everyone has been quick to point out just the loss of power in an OEI situation. But what about performance. Basic multi engine doctrine taught that with an engine failure on a twin aircraft. Not only did you lose half the power, but suffered an 80% degradation in aircraft performance. This being because now the failed engine is dead weight creating only drag. Most twin jets have nacelles and engines that have bigger surface area than the competing 3 or more aircraft.
So when you lose an engine on a trijet sure you've only lost 1/3 the power, but performance wise. Smaller engine, less weight, less drag. This probably means you can continue to cruise at higher altitudes and speeds for the given weights, temperatures, and etc. It was about 2 years ago that British Airways 747-400 lost an engine on departure out of LAX and continued it's flight to London. Would an twin engine whatever have done that? I am only using the BA flight as an example, I am not commenting on whether is was wrong or right.