Narrative:

MTR dove from above to avoid IMC conditions. He was above and ahead, dove to approximately our altitude then dove again lower. We were assigned FL280 and held it. He had no ATC clearance to descend and initiated it on his own. Initially we thought an aircraft was going down, but realized what was occurring by listening to ATC's side of conversation (other aircraft UHF-us and ATC VHF). Corrective action unnecessary since we had visual contact. Being behind we could observe what the pilot was attempting. To dive below the bases of oncoming clouds--in other words, avoiding IMC in the positive control area. I voluntarily called center after landing and found out the fighter pilot set-off the snitch-patch. Center was upset with his deviation. I became upset at his disregard for other aircraft and people.

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Original NASA ASRS Text

Title: MTR ALT DEVIATION EXCURSION FROM CLRNC ALT OBSERVED BY ACR MLG IN TRAIL IN PCA.

Narrative: MTR DOVE FROM ABOVE TO AVOID IMC CONDITIONS. HE WAS ABOVE AND AHEAD, DOVE TO APPROX OUR ALT THEN DOVE AGAIN LOWER. WE WERE ASSIGNED FL280 AND HELD IT. HE HAD NO ATC CLRNC TO DSND AND INITIATED IT ON HIS OWN. INITIALLY WE THOUGHT AN ACFT WAS GOING DOWN, BUT REALIZED WHAT WAS OCCURRING BY LISTENING TO ATC'S SIDE OF CONVERSATION (OTHER ACFT UHF-US AND ATC VHF). CORRECTIVE ACTION UNNECESSARY SINCE WE HAD VISUAL CONTACT. BEING BEHIND WE COULD OBSERVE WHAT THE PLT WAS ATTEMPTING. TO DIVE BELOW THE BASES OF ONCOMING CLOUDS--IN OTHER WORDS, AVOIDING IMC IN THE PCA. I VOLUNTARILY CALLED CENTER AFTER LNDG AND FOUND OUT THE FIGHTER PLT SET-OFF THE SNITCH-PATCH. CENTER WAS UPSET WITH HIS DEV. I BECAME UPSET AT HIS DISREGARD FOR OTHER ACFT AND PEOPLE.

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.