How long can I run LNAV and VNAV for...for example right after takeoff I usually put them both on....is this alright or should I wait a little longer....also when coming in for a landing I ussually bring it in pretty close til doing an ILS approach...should I do this diffrent...?Thank youChad Moore

Hi Chad,Simple answer is you can use as needed. For the climb-out after takeoff, in my IFR experience (flying GA), typically ATC will vector me to my first waypoint and then I assume own NAV so I typically use "HDG SEL" mode until I get a "direct to" from ATC to my first waypoint. I then use LNAV. Concerning VNAV, again it is dependent on ATC. I typically use "VNAV" or "LVL CHG" depending on climb instructions (mostly VNAV). Landing is a different story. I typically use VNAV and LNAV through a STAR, but then I use "CHG LVL" and "HDG SEL" modes for vectors to the approach. If you are setup for a precision approach such as an "ILS", then LNAV and VNAV are not appropriate. You should be using "APP" mode from the time ATC gives you a heading to intercept the "LOC" or clears you for the approach. For a non-precision "VOR" approach, I will typically use "VOR LOC", "CHG LVL" and the clock. Maybe a RW NG pilot could chime in for further info.Again, these examples are for a "Typical" flight. What mode to use when depends signficantly on the specific situation. This is why the autopilot has many different modes!

Thanks George ....I have one other question.....What does CHG LVL do for me...ThanksChad Moore

Hi Chad,Quoting from the manual:"The LVL CHG mode coordinates pitch and thrust commands to make automatic climbs and descents to preselected altitudes at selected airspeeds."Take a look in the PMDG documentation directory under FS at the "Aircraft Operating Manual". It explains the autopilot modes in detail.