The latest experience in fly gives a good lesson. The monopoly is ever dangerous because all resource is concentrated in one point, if this fall, fall many, many years of effort. So I do like Boeing sell the McDonnell Douglas Company to achieve a good balance of safety and improve its product with healthy competition. DC8 and DC10 was very good products. The last one fell because a bold & screw specification was not observed in the building process. Why?. I don't know the answer.