EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; General Declared Emergency
Aircraft; Weather
Level at FL360; extensive ice was building up on the windscreen; extensive ice on First Officer's TAT probe. Airspeed began to bleed off slowly; added more thrust; then a slow steady lateral or rolling oscillation began with the autopilot on; possibly from ice forming on some flight controls; accompanied by the Number 2 pack closing. Disconnected the autopilot; and reported the condition to ATC and then declared an emergency with a request to a lower altitude and heading north out of the weather. In the descent First Officer's airspeed indicator behaved like an altimeter and decreased to an airspeed of approximately 85 to 90 KTS while the Captain and standby indicated 260 KTS. Called the Flight Attendant and told her of the situation and had her check for extensive ice on the wings. She said there was none. After descending to FL300 and approximately 15 minutes had passed; the First Officer's airspeed came back and synchronized with the Captain's and standby airspeed indicators. All aircraft indications and flight characteristics returned to normal. [We] notified Dispatch to recalculate fuel for possible alternate landing airport. Possible severe icing.
First Officer; pilot flying; [we were] cruising at FL360; airspeed started to decrease. Added power and airspeed did not change. Aircraft started to oscillate and then the Number 2 pack closed. Asked ATC to descend and turned off autopilot. [We] noticed the ice only on the TAT probe and wind screen. Airspeed was decreasing in the descent to indicate around 80 KTS. Decided that the pitot tube must be clogged. Declared an emergency and started to use standby instruments and Captain's instruments. [We] tried to seek better weather. After reaching FL300; leveled off and exited the clouds. At some point we asked the flight attendants to check the wings. She reported no ice anywhere she could see. The flight instruments came back on and started working normal; so we decided to un-declare the emergency and continue on with the flight. I think we had some severe ice that blocked the pitot/static system and caused the oscillations.
EMB145 flight crew experiences failure of the First Officer's airspeed indicator in icing conditions at FL360. A descent is requested with the First Officer's airspeed indicator dropping to 80 KTS; with the Captain's and standby indicating 260 KTS at FL300. The First Officer's airspeed returns to normal upon exiting icing conditions.