On numerous occasions I have programmed the fmc for an arrival prior to the start of the trip and then when receiving ATIS from the arrival airport I need to change the runway. After putting in the new arrival I get a message "Arrival n/a for the runway". It then appears that the vnav doesn't work properly. The runway I select on the fmc does have the stars on selected as an option.

 

All it means is the arrival you originally programmed doesn't tie up with the new runway. So when you change the arrival runway you may need to change the STAR too. The way STARS are defined varies around the world and between airports, so there is no general advice to give apart from to try and find a chart for the airport online and see which STARs are appropriate for the each runway you might be offered.  Seeing all the different STARs on a chart makes it obvious why some are more appropriate than others, with regards to your direction of arrival and the runway assigned.

 

If you can't find a chart you can always delete the STAR and vector yourself to the new runway using HDG SEL and FLCH instead of LNAV and VNAV.

On numerous occasions I have programmed the fmc for an arrival prior to the start of the trip and then when receiving ATIS from the arrival airport I need to change the runway. After putting in the new arrival I get a message "Arrival n/a for the runway". It then appears that the vnav doesn't work properly. The runway I select on the fmc does have the stars on selected as an option.

 

This happens because you're kind of doing things out of order.  Selecting an arrival runway is usually one of the last things you'll do during a flight, but for some reason, simmers like to fill it out prior to departure.  The solution is actually rather simple: don't enter the runway so early.

 

The message is popping up - as it should - because some STARs have different instructions for different runways.  As an example, some of the STARs into IAD are listed as STAR.19 or STAR.01.  I can't select one of the 01 Runways for the STAR.19, and I can't select on of the 19 Runways for the STAR.01.  The best way to avoid this is to not even select a runway until you're already on the STAR (which is how it's generally done in the real world, too).  That way, if you have to change the STAR, there won't be a conflict.

All it means is the arrival you originally programmed doesn't tie up with the new runway. So when you change the arrival runway you may need to change the STAR too. The way STARS are defined varies around the world and between airports, so there is no general advice to give apart from to try and find a chart for the airport online and see which STARs are appropriate for the each runway you might be offered.  Seeing all the different STARs on a chart makes it obvious why some are more appropriate than others, with regards to your direction of arrival and the runway assigned.

 

If you can't find a chart you can always delete the STAR and vector yourself to the new runway using HDG SEL and FLCH instead of LNAV and VNAV.

Thanks for the response kevinh, my understanding is that the FMC will list only those stars applicable to the selected runway. I am usually on the star and see a need to change the runway based on the ATIS received. I hit dep/app on the FMC and select the new runway which lists the current star that I am on so I believe it should be ok, however, I still get the message.

Thanks for the response kevinh, my understanding is that the FMC will list only those stars applicable to the selected runway. I am usually on the star and see a need to change the runway based on the ATIS received. I hit dep/app on the FMC and select the new runway which lists the current star that I am on so I believe it should be ok, however, I still get the message.

In theory yes, but no doubt that relates to how the STAR is coded in the nav data. You can't blame PMDG for that. Anyway If you have a STAR and approach selected then change the approach it probably won't filter out the STAR that is already selected. To be sure it filtered them properly you would have to clear that STAR, choose the new runway and then see what STARs were listed. But as I said, there's no substitute for checking the chart.