B757 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Total 18000; Flight Crew Type 5000
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Aircraft; Weather
ATC warned us of moderate turbulence beginning in 20 minutes. We seated the passengers and flight attendants prior to that time. Without any warning; we encountered a rapid increase of airspeed of about 40 knots. Max speed was noted at .864 mach; 340 KTS. I immediately pulled the power to idle; the overspeed continued for about 20 seconds. I began a slow climb to bleed off speed. We gained less than 200 FT then went back to FL370. In seconds; the plane went from 310 KTS to 220 KTS. I increased thrust to the firewall and there was no increase of speed for about 10-15 seconds. We initiated a descent; with ATC clearance; to get back speed and at that time encountered moderate turbulence. We were in smooth air during the over/under speed and we are confident that no structural damage occurred. Many messages were exchanged between Dispatch and Maintenance; the decision was made to continue to destination. After stabilized; we attempted to locate the buffet speed chart in the manual on our Ipad's. It took me three attempts to login (error message about no wi-fi signal) and a total of more than 5 minutes to get to the performance section. No amount of searches could locate the appropriate document via the search function. I finally searched page by page in the performance chapter and found it. The use of the Ipad is not intuitive and would be vastly improved had I received instruction when given the Ipad.
B757 Captain reports encountering a mountain wave at FL370 which initially causes an over-speed and slight climb then an under-speed with a requested descent to regain speed with maximum power set. Difficulties finding performance information in the iPad are also reported.