Narrative:

Our aircraft departed ord runway 9R behind several large transport aircraft. There was a B787; two B737s; then our flight. All flights were spending minimum time on the runway prior to departure. Our airplane climbed to fra (flap retraction altitude) with altitude-T/O-1 (reduced) power and the airplane was reconfigured for the ord 2 departure profile. At approximately 1;600 ft AGL; the PF noted the pli (pitch limit indicator) displayed and rapidly approaching the flight director. The PF was hand-flying and reduced the pitch to approximately 8 degrees nose up. The airspeed was slowly accelerating through 170 knots with a wings-level; 'runway heading' straight climbout assigned. The pli continued to descend into the flight director and was observed to turn red followed by a momentary (1 sec) stick shaker actuation. The wake from the preceding aircraft was obviously felt as the PF continued to lower the pitch to approximately 3 degrees nose up as we continued to accelerate through the wake turbulence. As fast as the pli appeared; it vanished as we continued to climb and accelerate. Approximately 8-10 seconds later accelerating through 184 knots at an altitude of about 1;900 ft AGL; the pli again reappeared once again and descended into the flight director; turning red; and causing the stick shaker to activate briefly once again for about .5 seconds. Our aircraft could be felt to have entered and exited both burbles of wake turbulence as we continued our climb and acceleration to 240 knots. Total pitch attitude never exceeded a reasonable climb attitude (-0 deg and +8 deg) during the wake encounter. Total bank angle never exceeded an estimated 20 degrees either left or right. Our aircraft continued a normal climbout afterwards and proceeded to our landing destination with no further events. The biggest threat we faced was an assumed 'time pressure' with ATC while being cleared for takeoff behind a successive lineup of one heavy and two very large aircraft before our takeoff. We were given wake turbulence caution upon receiving our takeoff clearance. We underestimated the wake because all previous three departures were straight out keeping the wake over the departure end of the runway with a 4 knot quartering tailwind observed when beginning our takeoff roll. Another threat was that all departures were having the same 'runway heading' instructions on departure. An error made by the PF was the underestimation of the lingering effects of this wake phenomenon over the extended runway centerline. Also; 'max thrust' was not called for by the PF since the pli appeared and disappeared very quickly from the pfd suggesting that it would be a brief encounter with possible wake and that an aggressive thrust change would not be necessary. The PF felt that the steep pitch angle of the ord 2 departure could be sacrificed instead of adding excess thrust since we had already achieved fra and the airplane was configured for flaps 0 and accelerating already in a wings-level (maximum lift production) attitude. Another threat not associated with this event would have been the use of autopilot immediately after departure. It would have definitely caused an upset and a more significant roll/pitch dilemma if the pilot was not actively receiving feedback through the control column. Both PF and pm discovered this concept through effective communication during the wake turbulence event and recovery. The PF was glad to have been hand-flying when this event occurred to be able to take immediate action and respond with deliberate control inputs to keep the airplane from becoming a uas. Also; smooth rudder input prevented any unnecessary yaw/roll at the slower climbout speed.adopting standard separation minima and sticking with that should be a priority of ATC. Defined distances; rather than implied; should be mandated for keeping dangerous wake turbulence events to a minimum. Also; when given a takeoff clearance; do not rush the departure! Wait a few seconds to watch the preceding airplane and its flight path to see and evaluate where it goes! Consider briefing the input of maximum thrust when a possible wake turbulence encounter may exist! It's better to have the extra thrust already to preclude a secondary shaker activation. Also; do not use the autopilot if/when close separation between departures could pose a wake turbulence threat. Always hand fly up to fra so effective control feedback can be felt through the control column giving the PF the most accurate information possible necessary to thwart a wake turbulence/windshear encounter!

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Original NASA ASRS Text

Title: EMB-145LR Captain reported a brief stick shaker resulted from a wake turbulence encounter departing ORD.

Narrative: Our aircraft departed ORD Runway 9R behind several large transport aircraft. There was a B787; two B737s; then our flight. All flights were spending minimum time on the runway prior to departure. Our airplane climbed to FRA (Flap Retraction Altitude) with ALT-T/O-1 (reduced) power and the airplane was reconfigured for the ORD 2 departure profile. At approximately 1;600 ft AGL; the PF noted the PLI (Pitch Limit Indicator) displayed and rapidly approaching the flight director. The PF was hand-flying and reduced the pitch to approximately 8 degrees nose up. The airspeed was slowly accelerating through 170 knots with a wings-level; 'runway heading' straight climbout assigned. The PLI continued to descend into the flight director and was observed to turn red followed by a momentary (1 sec) stick shaker actuation. The wake from the preceding aircraft was obviously felt as the PF continued to lower the pitch to approximately 3 degrees nose up as we continued to accelerate through the wake turbulence. As fast as the PLI appeared; it vanished as we continued to climb and accelerate. Approximately 8-10 seconds later accelerating through 184 knots at an altitude of about 1;900 ft AGL; the PLI again reappeared once again and descended into the flight director; turning red; and causing the stick shaker to activate briefly once again for about .5 seconds. Our aircraft could be felt to have entered and exited both burbles of wake turbulence as we continued our climb and acceleration to 240 knots. Total pitch attitude never exceeded a reasonable climb attitude (-0 deg and +8 deg) during the wake encounter. Total bank angle never exceeded an estimated 20 degrees either left or right. Our aircraft continued a normal climbout afterwards and proceeded to our landing destination with no further events. The biggest threat we faced was an assumed 'time pressure' with ATC while being cleared for takeoff behind a successive lineup of one heavy and two very large aircraft before our takeoff. We were given wake turbulence caution upon receiving our takeoff clearance. We underestimated the wake because all previous three departures were straight out keeping the wake over the departure end of the runway with a 4 knot quartering tailwind observed when beginning our takeoff roll. Another threat was that all departures were having the same 'runway heading' instructions on departure. An error made by the PF was the underestimation of the lingering effects of this wake phenomenon over the extended runway centerline. Also; 'Max Thrust' was not called for by the PF since the PLI appeared and disappeared very quickly from the PFD suggesting that it would be a brief encounter with possible wake and that an aggressive thrust change would not be necessary. The PF felt that the steep pitch angle of the ORD 2 departure could be sacrificed instead of adding excess thrust since we had already achieved FRA and the airplane was configured for flaps 0 and accelerating already in a wings-level (maximum lift production) attitude. Another threat not associated with this event would have been the use of autopilot immediately after departure. It would have definitely caused an upset and a more significant roll/pitch dilemma if the pilot was not actively receiving feedback through the control column. Both PF and PM discovered this concept through effective communication during the wake turbulence event and recovery. The PF was glad to have been hand-flying when this event occurred to be able to take immediate action and respond with deliberate control inputs to keep the airplane from becoming a UAS. Also; smooth rudder input prevented any unnecessary yaw/roll at the slower climbout speed.Adopting standard separation minima and sticking with that should be a priority of ATC. Defined distances; rather than implied; should be mandated for keeping dangerous wake turbulence events to a minimum. Also; when given a takeoff clearance; do not rush the departure! Wait a few seconds to watch the preceding airplane and its flight path to see and EVALUATE where it goes! Consider briefing the input of MAX THRUST when a possible wake turbulence encounter MAY EXIST! It's better to have the extra thrust already to preclude a secondary shaker activation. Also; do not use the autopilot if/when close separation between departures could pose a wake turbulence threat. Always hand fly up to FRA so effective control feedback can be felt through the control column giving the PF the most accurate information possible necessary to thwart a wake turbulence/windshear encounter!

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.