B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Instructor
Flight Crew Last 90 Days 150; Flight Crew Total 11000; Flight Crew Type 3100
Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Took Evasive Action
Environment - Non Weather Related
[We were] departing IAH in a 737-800 at about 17;000 FT; 11 miles behind a 737-900 on the Junction departure over CUZZZ Intersection. Smooth air with wind on the nose bearing 275 degrees at 18 KTS. We were suddenly in moderate chop which lasted 4 or 5 seconds then stopped and then resumed for another 4 or 5 seconds with a significant amount of right rolling. Autopilot handled it; though I quickly moved my hands to the yoke to be ready to take the aircraft away from the autopilot if necessary. At this point I selected a max rate climb mode in the FMC in order to climb above the wake and flight path of the leading -900. We asked ATC for the type ahead of us and reported the wake encounter. The -900 was about 3;300 FT higher than we were. Both aircraft were climbing. No injuries in the back though the flight attendants were up and about preparing to start their service. My concern afterward was that our separation from the lead aircraft at 11 miles was enough that we could just as easily have been following a heavy aircraft with a much stronger wake.
B737-800 First Officer reported wake encounter from preceding B737-900 with resultant roll and moderate chop.