i am using pmdg with the fmc and i set up the fmc to fly from prestwick to stansteadwhich when i take off, controls the plane fine untill the ATC tells me to turn a different heading for the approach.how do i choose the approach on the FMC so it flys me in on the approach and lines me up for the runway?if i turn the heading atc wants then when i push lnav again it says not on intercept heading. and won't ingage,

Please have a read at the "Forum Rules" pinned in this forum: you are required to sign your real name on each and every post.Regarding your problem: LNAV is not made to cope with ATC vectoring.Once you're under radar vectoring, you are expected to fly the vectors given. You can have a little help using HDG mode, but do not expect LNAV to work.Eighter fly on LNAV, or follow FS ATC.Your choice.