Narrative:

We were alerted to ferry an empty -700 from bwi to ZZZ. Because of the very short distance of the flight; we briefed the departure; the arrival; and the approach into ZZZ. Via ACARS I retrieved the current ATIS for both locations. Dispatch filed us to go west of the dc area (frdmn) and then back to ZZZ and climb to 10;000 ft. Our clearance via cpdlc amended that to simply 'fly runway heading; climb and maintain 4000 ft.' the captain suspected that we might get short vectors and never go above 4000 ft; so he briefed that once the aircraft was cleaned up he would engage the autopilot and set lvl chng to ensure we did not pop through our altitude. Takeoff roll and initial climb were uneventful (with the exception that we were climbing very quickly since we were light weight) and passing about 1500 ft MSL we were clean. The captain engaged the autopilot and lvl chng and selected 220 knots to shallow out the climb. At approximately 3800 ft MSL we encountered what I believe was wake turbulence from a preceding aircraft and the autopilot kicked off. By the time we recognized that the autopilot was off we were already 300 ft above our altitude and still climbing. I called out 'altitude' at the same time the captain was pushing the nose over; we topped out at 4420 ft MSL. As we were descending through 4350ish; potomac approach called us to maintain 4000 ft. Ironically; we might have been better off just hand flying the aircraft instead of relying on the automation to keep us out of trouble. The turbulence and subsequent autopilot disengagement happened at exactly the wrong time.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737 NG First Officer reported overshooting their cleared altitude departing BWI after encountering possible wake turbulence.

Narrative: We were alerted to ferry an empty -700 from BWI to ZZZ. Because of the very short distance of the flight; we briefed the departure; the arrival; and the approach into ZZZ. Via ACARS I retrieved the current ATIS for both locations. Dispatch filed us to go west of the DC area (FRDMN) and then back to ZZZ and climb to 10;000 FT. Our clearance via CPDLC amended that to simply 'Fly runway heading; climb and maintain 4000 FT.' The Captain suspected that we might get short vectors and never go above 4000 FT; so he briefed that once the aircraft was cleaned up he would engage the autopilot and set LVL CHNG to ensure we did not pop through our altitude. Takeoff roll and initial climb were uneventful (with the exception that we were climbing very quickly since we were light weight) and passing about 1500 FT MSL we were clean. The Captain engaged the autopilot and LVL CHNG and selected 220 knots to shallow out the climb. At approximately 3800 FT MSL we encountered what I believe was wake turbulence from a preceding aircraft and the autopilot kicked off. By the time we recognized that the autopilot was off we were already 300 FT above our altitude and still climbing. I called out 'altitude' at the same time the Captain was pushing the nose over; we topped out at 4420 FT MSL. As we were descending through 4350ish; Potomac Approach called us to maintain 4000 FT. Ironically; we might have been better off just hand flying the aircraft instead of relying on the automation to keep us out of trouble. The turbulence and subsequent autopilot disengagement happened at exactly the wrong time.

Data retrieved from NASA's ASRS site 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.