B737-700 FLT CREW ENTERS ICING CONDITIONS WITHOUT THE PITOT HEAT ON; RESULTING IN ERRONEOUS INST INDICATIONS AND AN ACFT OVERSPD.
Synopsis
B737-700 FLT CREW ENTERS ICING CONDITIONS WITHOUT THE PITOT HEAT ON; RESULTING IN ERRONEOUS INST INDICATIONS AND AN ACFT OVERSPD.
Narrative
WHILE PUSHING RECALL; THE FO HAD TO MOVE THE RECALL BUTTON WITH HIS FINGERS TO MAKE THE LIGHTS GO OUT. AFTER HE DID; I PUSHED MY SIDE AND NO LIGHT WAS ON AFTER RECALL. UPON TKOF ROLL; THE MASTER CAUTION LIGHT CAME ON. I SAW THAT THE YAW DAMPER WAS OFF. I TURNED IT BACK ON AND SAID CONTINUE. UPON DEP FROM PDX; THE TWR TOLD US TO EXPECT MODERATE TURB. WE ENCOUNTERED MODERATE TURB AND MODERATE ICING AROUND 8000 FT MSL. WE HAD A L FMC FAIL. THE FO LOST HIS MAP AND HAD A FLAG. THE CAPT'S SIDE LOOKED NORMAL; SO I TOOK CTL. I NOTICED THE AIRSPD WAS AROUND 160 KTS ON BOTH THE STANDBY SYS AND THE HSI AIRSPEED. I DID NOT WANT TO PULL THE NOSE UP WITH THE AIRSPD THAT LOW THE CTLRS WERE VERY HVY; ALSO THE WIND NOISE WAS GETTING LOUDER BUT I DON'T THINK IT WAS REGISTERING THAT THE PITOT TUBES WERE BLOCKED. I WAS VERY CONCERNED ABOUT GOING INTO AN UNUSUAL ATTITUDE. I WAS VERY GENTLE ON THE YOKE. WE WERE IN IMC THE WHOLE TIME WITH MODERATE TURB AND MODERATE ICE. ABOUT THIS TIME THE FO SAW THAT THE PITOT HEAT WAS OFF. HE TURNED THE HEAT ON AND THE SYS CAME UP NORMALLY. GOD LOVE MY FO! WE HAD AN OVERSPD CLACKER SHORTLY AFTER TURNING THE HEAT BACK ON; WE CLBED TO A LOWER THAN FILED CRUISE ALT AND LANDED AT LAX. WE ALSO CRUISED AT A LOWER THAN FILED CRUISE SPD FOR THE OVERSPD EVENT. WHILE I THOUGHT I TURNED THE HEAT ON; I MOST LIKELY DID NOT AND WITH RECALL LIGHT PROB I MIGHT HAVE OVERLOOKED IT. SUPPLEMENTAL INFO FROM ACN 690373: AFTER THROTTLES HAD ADVANCED AND STABILIZED; THE MASTER CAUTION LIGHT CAME ON. I HAD NO INDICATIONS ON MY ANNUNCIATOR. I THOUGHT THE CAPT SAID LNAV DISCONNECT; AS I HAD PUSHED LNAV BUT IT DID NOT ENGAGE ON THE GND -- TOO BIG OF AN ANGLE BTWN LNAV AND RWY. THE MASTER CAUTION WENT OUT AND HE SAID 'CONTINUE.' AFTER THE WAYPOINT CROWN; WE TURNED TO A HDG OF 120 DEGS. WE ENTERED THE CLOUDS; TURB AND LIGHT ICING/SNOW. I WAS HAND FLYING AND NOTICED MY VERT GUIDANCE DISAPPEARED. I TOLD THE CAPT; THEN I NOTICED MY AIRSPD WAS SLOWING. I HELD A PITCH OF ABOUT 10 DEGS AND MADE SURE THE THROTTLES WERE UP AND GOOD INDICATIONS ON ENG INSTS. THE CAPT WAS SAYING WE WERE GETTING TOO SLOW; SO I STARTED TO LOWER THE NOSE A FEW DEGS. THE TURB WAS GETTING WORSE. THE CAPT SAID HE HAD THE CTLS AND AT WHICH POINT I LOOKED AT THE OVERHEAD PANEL AND SAW THE PITOT PROBE HEAT OFF. I TURNED THE PITOT PROB HEAT ON AND THE AIRSPD CAME BACK; AND ENTERED INTO THE RED HASH. I SAID WE WERE GOING TOO FAST AND HAD TO SLOW. THE CAPT GAVE ME THE CTLS. I HELD THE THROTTLES BACK UNTIL WE WERE AT 250 KTS; GOT THE AUTOPLT ENGAGED. WE WERE AT ABOUT 10000 FT AT THIS TIME. I SAW THE AIRSPD AT 320 KTS OR SO AND HEARD THE CLACKER BEFORE SLOWING. AT THIS TIME MY INNER 'DU' HAD THE MAP FLAG DISPLAYED. WE CLBED; RESTORED DUAL FMC AND THE REST OF THE FLT WAS UNEVENTFUL. SUPPLEMENTAL INFO FROM ACN 690564: I DID NOT GET TO SLEEP UNTIL 2 O'CLOCK AM THE DAY OF THE INCIDENT. I AWOKE AT APPROX 5:30 O'CLOCK AM AND WAS UNABLE TO RETURN TO A RESTFUL SLEEP BECAUSE OF MAID SVC; WEED BLOWER IN ANOTHER HOTEL'S PARKING LOT; AND MAINT WAS BEING PERFORMED ON SOME OF THE TELEVISIONS ON MY FLOOR.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.