I just recently got the pmdg 737. I have done the first tutorial flight only two times now. On the 2nd time I did the first tutorial I got the message saying nav out of date on the fmc. I just cleared it out. But I am not sure if this is gonna effect future flights? Thanks.

You can ignor the Nav Data Out of Date message, or choose to update the data (updated nav data is published every month) through a source like Navigraph ( www.navigraph.com ). The 737NGX comes with nav data that was current when PMDG initially released the a/c, so it is out of date and thus you get the message. Suggest you read through the two threads below to get a sense of what different people think regarding the value of updating the nav data (which you can choose to do every month, a few times a year, once a year, never, etc).  What makes sense for you depends on what type of flying you will be doing with the 737NGX.

 

http://forum.avsim.net/topic/377023-navigraph-explanation-please/

http://forum.avsim.net/topic/350750-nav-data-out-of-date/

 

Al