B737-700
Flight Crew Last 90 Days 419; Flight Crew Type 5500
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action
Aircraft; Weather
MEL 35-4-02 requires flight below FL250 with two unusable POBs [Portable Oxygen Bottle]. Heavy weather and icing at filed FL240 dictated a climb above the weather for safety of flight. Captain exercised emergency authority and elected to climb out of the poor weather conditions. Note: During climb to get out of poor weather conditions; excessive engine vibration was noted on #2 engine and the Engine Vibration Checklist had to be accomplished; suspected ice on the fan blades. Approximately 12 minutes of flight was conducted in the clear at FL340. Once passed heavy precipitation conditions; a descent back down to FL240 was made. Remainder of flight was uneventful and accomplished below FL250 per MEL 35-4-02.
We were cruising at FL240 due to an MEL restriction that restricted us to FL250 due to two POBs used on the previous flight for a medical emergency. We encountered a wide line of weather and experienced moderate rime icing. We elected to climb to FL330 since ATC advised this altitude was above the weather. We stayed at FL330 above the weather until clear of the line and then descended back to FL240 as soon as possible.
B737 flight crew reports being dispatched with an MEL requiring flight at FL250 and below. Enroute heavy weather and icing conditions are encountered and the crew elects to climb to FL340 until clear of the weather 12 minutes later.