Date: 201704
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: 2
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Weather
Primary problem: Weather

Narrative: This was our first day working as a Crew on our final third leg assignment. Our flight was 35 minutes late due to FA connection and thunderstorms were present in ZZZ. The ATIS was changing rapidly and provided 4 updates in less than an hour; pressure dropped from 29.60 to 29.50 in the 30 minutes prior to departure. We taxied to Runway XXC for departure at ZZZ; and were encountering extended taxi time as several aircraft went missed due to low ceilings and ZZZ Tower was issuing 20 miles in trail separation with simultaneous departures off Runway YR and XXC and landing YR. ATC congestion was busy and the Tower was doing a good job reporting the rapidly changing weather conditions with wind and pressure reports. As we neared our departure sequence the intensity of rainfall and lightning was increasing. No adverse windshear reports were present on the field and no aircraft were reporting any windshear after takeoff. Prior to our clearance to taxi into position on XXC; the Captain requested an updated wind report from Tower. The Tower reported wind direction at 100 and speed of 8 knots. We updated this data in the Performance Computer which directed a new flap setting of 10 degrees. We completed the Departure Plan Checklist and set the flaps accordingly. Additionally the Performance Computer data included windshear; max thrust; and wet good settings. The hold down VR was 126 if I recall correctly based on a 142.2 takeoff weight. The Captain did a good job of briefing the windshear profile; should we encounter it after takeoff. He reviewed the emergency thrust; and configuration callouts which helped to develop our shared mental model. Tower informed us that the weather had cleared the runway moving east rapidly and to use caution for frequent lightning in the area. ZZZ Tower issued takeoff clearance off XXC and to turn to heading of 090. We initiated the takeoff and complied with the wind shear profile VR takeoff. Shortly after raising the landing gear; I observed a significant decrease in airspeed of 15 knots. I called out wind shear to the Captain and I increased the thrust above max thrust setting. The Captain began a reduction in pitch to compensate for the degraded airspeed when the EGPWS declared WIND SHEAR decreasing performance warning. The Captain immediately pushed the thrust to emergency thrust and began following the escape guidance. I began calling out airspeed and altitude trends and it took a short time for the aircraft to display positive trends. The windshear event was brief; but had a significant negative performance effect on the aircraft. As the windshear warning extinguished; the Captain directed necessary MCP mode changes to prevent flap over speed during retraction. I alerted the Tower of our windshear event and 20 knot airspeed loss. ZZZ Tower ceased departures after our report. We still had a heading and 3000 FT hold down altitude to comply with while changing to Departure frequency. We did not observe any engine exceedance but our focus at the time was on aircraft recovery. Lighting in the area was very bright and proved to be a significant distraction. We contacted Dispatch via ACARS in cruise and informed them of the windshear encounter and to ask Maintenance if they received any engine exceedance. The rest of the flight was without incident and we contacted Maintenance at destination to discuss if a Maintenance entry was required. The Captain and I reviewed the event and discussed if there was anything we could have improved during the recovery. Between the two of us this was the first time in our airline career that we had ever encountered a true windshear event after takeoff. I explained the best practice in dealing with a windshear event is to not ever be in a position to encounter one in the first place. My position was that while we knew of thunderstorms in the airport vicinity; there were no adverse reports of windshear reporting on the airport; or by the multiple aircraft departing ahead of us.  There was no information that would lead us to have delayed or discontinued the takeoff as the predictive windshear did not alert either.  We believed our practice of updating the takeoff data to reflect the most accurate winds was good practice as was our discussion of the windshear profile plan should it be encountered. I believe our CRM measures proved to be a valuable tool in managing the threat. However; I will conclude with RRM (Risk and Resource Management) perhaps being the most overlooked aspect of this situation. Risk is inherent in what we do; but weather like this in proximity to ZZZ proves to be a high risk environment; and we could have possibly benefited from more information with Dispatch as a resource offering guidance to help manage or aide in the operation as a whole in determining the factors involved when operating multiple flights in a high threat environment.




Synopsis: B737NG First Officer reported experiencing windshear shortly after gear retraction. An EGPWS wind shear warning and an airspeed loss both occur as the Captain recovered using maximum thrust.