B747 flight crew reports airspeed discrepancy and ultimate failure of first officer's airspeed indic...

Attributes
ACN	858357
Time
Date	200910
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B747-400
Component
Aircraft Component	Air Data Computer
Person 1
Function	Pilot Not Flying
Experience	Flight Crew Last 90 Days 255 Flight Crew Total 16000 Flight Crew Type 10700
Person 2
Function	Captain Pilot Flying
Experience	Flight Crew Last 90 Days 230 Flight Crew Total 30000 Flight Crew Type 10000
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Speed All Types

Narrative:

As the relief pilot; after checking the engines and egt; I noticed a difference in airspeeds and called out 20 KTS airspeed difference out loud. The captain stated he would use the lowest airspeed or rotate with 2000 ft remaining. I checked the airspeed with the stby instruments and saw that the captain's instruments were the same and the first officer's were slower. We rotated; climbed out; and cleaned up. I asked for the QRH to accomplish the airspeed disagree checklist. The first officer's instruments failed and the first officer and I ran the checklist. We coordinated with ATC and called dispatch and maintenance. I got the weather for ZZZ1 and ZZZ2 and the first officer checked the divert checklist and rvsm requirements. It was decided that we should return to ZZZ. We dumped fuel and the descent and landing was uneventful.

Original NASA ASRS Text

Title: B747 Flight Crew reports airspeed discrepancy and ultimate failure of First Officer's airspeed indicator during and after takeoff. Fuel is dumped and flight returns for uneventful landing.

Narrative: As the relief pilot; after checking the engines and EGT; I noticed a difference in airspeeds and called out 20 KTS airspeed difference out loud. The Captain stated he would use the lowest airspeed or rotate with 2000 FT remaining. I checked the airspeed with the stby instruments and saw that the Captain's instruments were the same and the First Officer's were slower. We rotated; climbed out; and cleaned up. I asked for the QRH to accomplish the Airspeed Disagree Checklist. The First Officer's instruments failed and the First Officer and I ran the checklist. We coordinated with ATC and called dispatch and maintenance. I got the weather for ZZZ1 and ZZZ2 and the First Officer checked the divert checklist and RVSM requirements. It was decided that we should return to ZZZ. We dumped fuel and the descent and landing was uneventful.

Data retrieved from NASA's ASRS site as of April 2012 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.

B747 flight crew reports airspeed discrepancy and ultimate failure of first officer's airspeed indicator during and after takeoff. Fuel is dumped and flight returns for uneventful landing.