Narrative:

Captain and copilot's pitot static system in error. Airspeed difference 18 KT altitude 1300 ft. At cruise TAS calculations indicated copilot's instruments most accurate.

Google
 

Original NASA ASRS Text

Title: ACR WDB EXPERIENCES A PROBLEM WITH ITS KIFIS PITOT STATIC SYS WHILE CLBING OUT AND LEVELING ON AN EXTENDED OVERWATER OP.

Narrative: CAPT AND COPLT'S PITOT STATIC SYS IN ERROR. AIRSPD DIFFERENCE 18 KT ALT 1300 FT. AT CRUISE TAS CALCULATIONS INDICATED COPLT'S INSTS MOST ACCURATE.

Data retrieved from NASA's ASRS site as of July 2007 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.