B757 captain reports encountering a mountain wave at FL370 which initially causes an over-speed and ...

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

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.

Attributes
ACN	1068232
Time
Date	201302
Local Time Of Day	0001-0600
Place
Locale Reference	ZDV.ARTCC
State Reference	CO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Tablet
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 18000 Flight Crew Type 5000
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence

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.