Boeing Co (BA.N) said on Wednesday it would slow production of its 747-8 jumbo jet by 23 percent to one per month starting in March, an effort to keep the production line running amid sluggish demand for the iconic, humped-top plane. Boeing, the world’s largest plane maker, is currently building 747s at a rate of 1.5 a month and had already announced plans to reduce the rate to 1.3 a month from September. The company said the decision to slow production further was not related to Tuesday’s announcement that President Dennis Muilenburg will succeed Jim McNerney as chief executive on July 1.