Narrative:

XXXX en route at FL180 advised me of a battery overheat condition and that he needed lower immediately. I descended aircraft to 11000 ft and asked if he was declaring an emergency or needed assistance. He said 'no,' but right after that I lost radar contact with him. About 1 min later, he said the situation was becoming more serious, as he thought he might have a battery fire. He said he wanted to land as soon as possible and asked if his arrival airport (still 50 mi away) was the closest. I said 'no' and cleared him to fay, 7 mi off his right. Aircraft declared emergency with approach control and landed safely. This was a pilot who kept his cool and continued to re-evaluate the condition of his aircraft. Had he chosen to press on to his original destination, the outcome might have been different. Callback conversation with reporter revealed the following information: controller was not made aware of final determination to cause of problem by pilot.

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Original NASA ASRS Text

Title: C501 ADVISES ZDC CTLR OF BATTERY OVERHEAT PROB, DECLARES AN EMER AND LANDS AT FAY DUE TO CONTINUED DEVELOPING PROBS.

Narrative: XXXX ENRTE AT FL180 ADVISED ME OF A BATTERY OVERHEAT CONDITION AND THAT HE NEEDED LOWER IMMEDIATELY. I DSNDED ACFT TO 11000 FT AND ASKED IF HE WAS DECLARING AN EMER OR NEEDED ASSISTANCE. HE SAID 'NO,' BUT RIGHT AFTER THAT I LOST RADAR CONTACT WITH HIM. ABOUT 1 MIN LATER, HE SAID THE SIT WAS BECOMING MORE SERIOUS, AS HE THOUGHT HE MIGHT HAVE A BATTERY FIRE. HE SAID HE WANTED TO LAND ASAP AND ASKED IF HIS ARR ARPT (STILL 50 MI AWAY) WAS THE CLOSEST. I SAID 'NO' AND CLRED HIM TO FAY, 7 MI OFF HIS R. ACFT DECLARED EMER WITH APCH CTL AND LANDED SAFELY. THIS WAS A PLT WHO KEPT HIS COOL AND CONTINUED TO RE-EVALUATE THE CONDITION OF HIS ACFT. HAD HE CHOSEN TO PRESS ON TO HIS ORIGINAL DEST, THE OUTCOME MIGHT HAVE BEEN DIFFERENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CTLR WAS NOT MADE AWARE OF FINAL DETERMINATION TO CAUSE OF PROB BY PLT.

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.