Narrative:

Landing gear failed to retract after takeoff. Followed checklist and called ZZZZ maintenance and ZZZ technician for troubleshooting. Could not determine cause and declared emergency with ATC. Briefed flight attendants and passenger and returned for a normal uneventful landing. ZZZZ maintenance determined problem to be 'proximity detector processing unit.' after airplane was fixed; we flew flight to ZZZ1 and had normal gear operations.

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Original NASA ASRS Text

Title: A300-600R AIRBUS FLT CREW IS UNABLE TO RAISE THE LNDG GEAR AFTER TKOF; DECLARES AN EMER AND RETURNS TO THEIR DEP ARPT.

Narrative: LNDG GEAR FAILED TO RETRACT AFTER TKOF. FOLLOWED CHKLIST AND CALLED ZZZZ MAINT AND ZZZ TECHNICIAN FOR TROUBLESHOOTING. COULD NOT DETERMINE CAUSE AND DECLARED EMER WITH ATC. BRIEFED FLT ATTENDANTS AND PAX AND RETURNED FOR A NORMAL UNEVENTFUL LNDG. ZZZZ MAINT DETERMINED PROB TO BE 'PROX DETECTOR PROCESSING UNIT.' AFTER AIRPLANE WAS FIXED; WE FLEW FLT TO ZZZ1 AND HAD NORMAL GEAR OPS.

Data retrieved from NASA's ASRS site as of January 2009 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.