Do I need to be at FL180 when I reach Tulsawaypoint at 157 degrees? I am flying BYP5 approach. It is 161 miles to the BYP waypoint from Tulsa. It doesn't make since to fly at FL180 for 161 miles. Can anyone explain this.Here is the link for the STAR chart for KDFWhttp://flightaware.com/resources/airport/KDFW/STAR/BONHAM+FIVE

FL180 is not mandatory. FL180 is the minimum enroute atitude.

My cruise ALT is FL350. what would I put then for TUL waypoint alitude? I set it at FL180 and the flew at FL180 for 161 miles and then down to 5000.

It looks like depending on which way you are landing, you would plan for crossing LEMYN or KARLA at 11,000 so set that as your target assuming descend at pilot's discretion. Then monitor your descent and if you are getting close to the min for a segment do an alt hold.scott s..

Okay. It shows KARLA at 5000 though. My FMC was set DOSOA- FL350, then TUL- FL180, KARLA- 5000 and then the FMC took over for COVIE etc. If KARLA shows 5000ft why would LEMYN be 11,000? It is closer to the airport. I feel stupid asking these questions but I am trying to be accurate instead of letting FS ATC tell me what to decend to throughout the entire flight. Is there maybe a good tutorial video to watch?

The altitudes depicted along the route are only minimum altitudes for those segments. Many of these FSX FMCs treat a minimum altitude as a mandatory altitude. Absent other instructions from ATC, set your FMS for KARLA at 11000 and 280 kts. landing north, or 11000 and 250 kts. landing south, with no other altitudes below cruise.