Rain water which accumulated in a B757 east and east compartment flowed onto several computers at ro...

Narrative:

On initial taxi first officer airspeed and altimeter inoperative flags for a brief second and cleared. Later in the taxi captain's flight data (FD) failed and alternate source was selected problem cleared. After takeoff first officer flying at 800 ft AGL captain's airspeed and altimeter failed seemingly all captain's instruments went crazy with erroneous windshear and GPWS warnings. These warnings continued for several minutes. EICAS showed we had a mach/speed trim and rudder ratio failure. Center notified us they had a zero altitude readout from our transponder. Captain's instruments climbed and then descended warnings of too low terrain...whoop whoop pull up...terrain ...climb...too slow...flaps...you name it. First officer had good indications with autothrottles appearing to lag or inoperative. Initially leveling at 3;000 ft and then climbing to 6;000 ft running checklists with a very noisy and busy flight deck. The decision was made to divert back to the departure airport. ATC asked us if we wanted to declare emergency. We said no. Once setting up for approach and informing company we descended to 3;000 ft and were then cleared for localizer 30. With all the distractions horns and whistles we decided to not get an air return clearance from dispatch. We talked about it but decided to just get airplane on ground. Leveling at 3;000 ft captain's instruments appeared more normal. Gear down and flaps 30 was done early. Speed for flaps 30 was 128 plus 5...target speed 133. At one point all airspeeds showed 135 to 138 yet we had the alpha showing in the ADI. First officer was getting fast/slow flashing both fast and slow in his ADI. Captain's side showed the alpha as well. I did not notice fast/slow on my side. Both landing and taxi in was normal. I'm not sure what we could have done different to prevent this.

Original NASA ASRS Text

Title: Rain water which accumulated in a B757 E and E compartment flowed onto several computers at rotation causing the loss of several Captain's flight instruments; so the crew returned to the departure airport.

Narrative: On initial taxi First Officer airspeed and altimeter inoperative flags for a brief second and cleared. Later in the taxi Captain's Flight Data (FD) failed and alternate source was selected problem cleared. After takeoff First Officer flying at 800 FT AGL Captain's airspeed and altimeter failed seemingly all Captain's instruments went crazy with erroneous windshear and GPWS warnings. These warnings continued for several minutes. EICAS showed we had a Mach/SPD trim and rudder ratio failure. Center notified us they had a zero altitude readout from our transponder. Captain's instruments climbed and then descended warnings of TOO LOW TERRAIN...WHOOP WHOOP PULL UP...TERRAIN ...CLIMB...TOO SLOW...FLAPS...you name it. First Officer had good indications with autothrottles appearing to lag or inoperative. Initially leveling at 3;000 FT and then climbing to 6;000 FT running checklists with a very noisy and busy flight deck. The decision was made to divert back to the departure airport. ATC asked us if we wanted to declare emergency. We said no. Once setting up for approach and informing company we descended to 3;000 FT and were then cleared for LOC 30. With all the distractions horns and whistles we decided to not get an air return clearance from Dispatch. We talked about it but decided to just get airplane on ground. Leveling at 3;000 FT Captain's instruments appeared more normal. Gear down and flaps 30 was done early. Speed for flaps 30 was 128 plus 5...target speed 133. At one point all airspeeds showed 135 to 138 yet we had the ALPHA showing in the ADI. First Officer was getting Fast/Slow flashing both fast and slow in his ADI. Captain's side showed the ALPHA as well. I did not notice fast/slow on my side. Both landing and taxi in was normal. I'm not sure what we could have done different to prevent this.

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	1039085
Time
Date	201209
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZZ.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 70 Flight Crew Total 11000 Flight Crew Type 4000
Person 2
Function	First Officer Pilot Flying
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 13000 Flight Crew Type 700
Events
Anomaly	Aircraft Equipment Problem Critical

Rain water which accumulated in a B757 east and east compartment flowed onto several computers at rotation causing the loss of several captain's flight instruments; so the crew returned to the departure airport.