Narrative:

[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.

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Original NASA ASRS Text

Title: B737-800 First Officer reported wake encounter from preceding B737-900 with resultant roll and moderate chop.

Narrative: [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.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.