Emb-175 first officer reported that an altitude excursion; aircraft overspeed; and moderate turbulen...

Narrative:

At FL350; we started to experience light chop and the captain turned the seat belt sign on. Shortly after; we experienced mountain wave action with moderate turbulence. The captain immediately started to reduce the thrust to compensate for the raising airspeed as we tried to maintain altitude. I made a public address (PA); for passengers and flight attendants to take their seats and fasten their seat belts. As the captain tried to maintain altitude; the airspeed was rapidly rising. He told me that we were unable to maintain altitude and to advise ATC. I advised ATC we were unable to maintain altitude due to an updraft and needed higher and requested a block of FL350-FL360. ATC cleared us for the block. As the captain was recovering; the high-speed oral warning went off; but never received the associated master warning for high speed. As we continued the recovery process; I advised ATC we needed lower to FL330 for moderate turbulence. ATC cleared us to FL330 and passing through FL335; we entered smooth air. We reported to ATC that we experienced moderate turbulence with mountain wave action of plus or minus 500 feet and plus or minus 30 knots. After we reached FL330; the captain checked with the flight attendants to see if they and the passengers were okay; they were.

Original NASA ASRS Text

Title: EMB-175 First Officer reported that an altitude excursion; aircraft overspeed; and moderate turbulence resulted from a mountain wave encounter at FL350.

Narrative: At FL350; we started to experience light chop and the Captain turned the seat belt sign on. Shortly after; we experienced mountain wave action with moderate turbulence. The Captain immediately started to reduce the thrust to compensate for the raising airspeed as we tried to maintain altitude. I made a Public Address (PA); for passengers and Flight Attendants to take their seats and fasten their seat belts. As the Captain tried to maintain altitude; the airspeed was rapidly rising. He told me that we were unable to maintain altitude and to advise ATC. I advised ATC we were unable to maintain altitude due to an updraft and needed higher and requested a block of FL350-FL360. ATC cleared us for the block. As the Captain was recovering; the high-speed oral warning went off; but never received the associated master warning for high speed. As we continued the recovery process; I advised ATC we needed lower to FL330 for moderate turbulence. ATC cleared us to FL330 and passing through FL335; we entered smooth air. We reported to ATC that we experienced moderate turbulence with mountain wave action of plus or minus 500 feet and plus or minus 30 knots. After we reached FL330; the Captain checked with the Flight Attendants to see if they and the passengers were okay; they were.

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.

Attributes
ACN	1514340
Time
Date	201801
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	EMB ERJ 170/175 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence

Emb-175 first officer reported that an altitude excursion; aircraft overspeed; and moderate turbulence resulted from a mountain wave encounter at FL350.