Narrative:

While cruising at FL270 near greensboro, nc, in contact with atl ARTCC we approached an area between 2 thunderstorm cells. We asked center if we could climb to FL290 to avoid the WX. Center answered unable due to crossing traffic at FL280. We could maintain VFR between the 2 cells and proceeded between them when lightning began to arc cloud to cloud immediately in front of our aircraft. Unless our altitude was increased immediately, a lightning strike was imminent. The captain advised that we must climb and to notify ATC. The center frequency was congested. Finally, I was able to break in on the frequency and advise center that we must leave FL270 to avoid the WX and are climbing. We maintained VFR and had the FL280 traffic in sight. We climbed approximately 600' to clear the arcing lightning and then descended to FL270. Center asked our altitude as we descended and we advised them we were at FL273. We were subsequently cleared to FL290. The crossing aircraft appeared to be a 2 engine turbo propeller and we advised center we had it in sight. The captain had no choice but to climb to avoid an almost certain encounter with a lightning strike. Under the circumstances, an altitude deviation in VFR with traffic insight was better than sustaining a lightning strike on the aircraft and the potential disaster that could result. If other aircraft had not congested the frequency with nonessential communications, we might have been able to advise center of the situation sooner.

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Original NASA ASRS Text

Title: PURPOSELY DEVIATED FROM ASSIGNED ALT TO AVOID IMMINENT LIGHTNING STRIKE. HAD CROSSING TRAFFIC IN SIGHT. NOTIFIED CENTER WHEN ABLE TO BREAK INTO CONGESTED FREQ. RETURNED TO ASSIGNED ALT.

Narrative: WHILE CRUISING AT FL270 NEAR GREENSBORO, NC, IN CONTACT WITH ATL ARTCC WE APCHED AN AREA BTWN 2 TSTM CELLS. WE ASKED CENTER IF WE COULD CLB TO FL290 TO AVOID THE WX. CENTER ANSWERED UNABLE DUE TO XING TFC AT FL280. WE COULD MAINTAIN VFR BTWN THE 2 CELLS AND PROCEEDED BTWN THEM WHEN LIGHTNING BEGAN TO ARC CLOUD TO CLOUD IMMEDIATELY IN FRONT OF OUR ACFT. UNLESS OUR ALT WAS INCREASED IMMEDIATELY, A LIGHTNING STRIKE WAS IMMINENT. THE CAPT ADVISED THAT WE MUST CLB AND TO NOTIFY ATC. THE CENTER FREQ WAS CONGESTED. FINALLY, I WAS ABLE TO BREAK IN ON THE FREQ AND ADVISE CENTER THAT WE MUST LEAVE FL270 TO AVOID THE WX AND ARE CLBING. WE MAINTAINED VFR AND HAD THE FL280 TFC IN SIGHT. WE CLBED APPROX 600' TO CLR THE ARCING LIGHTNING AND THEN DSNDED TO FL270. CENTER ASKED OUR ALT AS WE DSNDED AND WE ADVISED THEM WE WERE AT FL273. WE WERE SUBSEQUENTLY CLRED TO FL290. THE XING ACFT APPEARED TO BE A 2 ENG TURBO PROP AND WE ADVISED CENTER WE HAD IT IN SIGHT. THE CAPT HAD NO CHOICE BUT TO CLB TO AVOID AN ALMOST CERTAIN ENCOUNTER WITH A LIGHTNING STRIKE. UNDER THE CIRCUMSTANCES, AN ALT DEVIATION IN VFR WITH TFC INSIGHT WAS BETTER THAN SUSTAINING A LIGHTNING STRIKE ON THE ACFT AND THE POTENTIAL DISASTER THAT COULD RESULT. IF OTHER ACFT HAD NOT CONGESTED THE FREQ WITH NONESSENTIAL COMS, WE MIGHT HAVE BEEN ABLE TO ADVISE CENTER OF THE SITUATION SOONER.

Data retrieved from NASA's ASRS site as of August 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.