What was found
BURNING SMELL IN FLIGHT. PACK 2 IN MANUAL MODE, ALL THE WAY COLD. CREW PUT THE PACK 2 BACK IN AUTO MODE, AND THE SMELL SEEMED TO CLEAR. ALL INDICATIONS NORMAL, NO EICAS MESSAGES. POWER SETTING NEAR IDLE WHEN IT HAPPENED. NO SMOKE BAGGAGE/LAV ALARMS OR VISIUAL INDICATIONS. COCKPIT AND CABIN, STRONG SMELL, SMELLED LIKE A BURNING MATCH, NO VISIBLE INDICATIONS IN COCKPIT, A SLIGHT HAZE IN THE CABIN, AROUND ROW 9 AND 11, LASTED 3-5 MINUTES. DURING DECENT, 21,000FT DESCENDING BLEED 1/2 ON, APU BLLED OFF, CROSS BLEED AUTO, BOTH PACKS ON. HAPPENED IN ICING CONDITIONS, DID NOT DEICE PRIOR TO TAKEOFF. COMPLIED WITH FIM. NO SMELL PRESENT. NO FAULTS FOUND. VISUALLY INSPECTED #2 ACM. NO DEFECTS NOTED AT THIS TIME.