|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||airport : hgr.airport|
|Altitude||msl bound lower : 7500|
msl bound upper : 11000
|Controlling Facilities||artcc : zdc.artcc|
|Operator||general aviation : personal|
|Make Model Name||Bonanza 35|
|Operating Under FAR Part||Part 91|
|Flight Phase||cruise : level|
|Function||flight crew : single pilot|
|Qualification||pilot : atp|
|Experience||flight time last 90 days : 40|
flight time total : 19000
flight time type : 80
|Affiliation||government : faa|
|Function||controller : radar|
|Anomaly||aircraft equipment problem : critical|
other anomaly other
|Independent Detector||aircraft equipment other aircraft equipment : dual gps ald indications|
|Resolutory Action||flight crew : became reoriented|
flight crew : exited adverse environment
flight crew : overcame equipment problem
|Problem Areas||Flight Crew Human Performance|
Leg #3 of aircraft delivery (change of ownership) to 0g7. Aircraft previously had been based south florida for more than 3 months and tied down outside. Cruise VFR flight at 7500 ft; radar en route with ZDC (flight following). Situation: engine manifold indication observed gradually decreasing (15 mins estimated interval) from full throttle setting of 22 inches; deterioration continued to 17 inches. Flight conditions clear and cold (-10 degrees C; outside air temperature). Carburetor heat applied -- no relief. Flight instruments normal -- altitude indicating 7500 ft; stable. Decision made to descend to warmer more dense air. Descent initiated and discovered all pitot static instruments frozen in position. Airspeed zero. Applied pitot heat -- no immediate change. Consulted both GPS's for back-up flight conditions and found altitude indications of about 11000 ft; ground speed 89 KTS; outside air temperature was much colder than previously observed -20 degrees C. Initially I was incredulous concerning GPS altitude information; but realized it all added up. We had climbed 3500 ft without knowing it. Our only indication of a problem was decreasing manifold indications. Corrective action: informed ZDC of problem and altitude. Continued VFR flight using GPS altitude indications descending to 7500 ft where engine indications returned to normal. All pitot static indications remained frozen; with the exception of airspeed; which steadily increased to full scale 250 KIAS. Flight completed to 0g7 uneventfully.
Original NASA ASRS Text
Title: BE35 PLT IS SHOCKED TO DISCOVER HIS ACFT HAS CLBED FROM 7500 FT TO APPROX 11000 FT WITHOUT REGISTERING THE CHANGE ON HIS PITOT STATIC INSTS WHICH TURNED OUT TO HAVE ICED UP. BECAME AWARE THROUGH RESEARCH OF MYSTERIOUSLY FALLING MANIFOLD PRESSURE WHICH LED HIM TO INVESTIGATE ALT READOUTS OF 2 GPS NAV SYS ON BOARD.
Narrative: LEG #3 OF ACFT DELIVERY (CHANGE OF OWNERSHIP) TO 0G7. ACFT PREVIOUSLY HAD BEEN BASED S FLORIDA FOR MORE THAN 3 MONTHS AND TIED DOWN OUTSIDE. CRUISE VFR FLT AT 7500 FT; RADAR ENRTE WITH ZDC (FLT FOLLOWING). SIT: ENG MANIFOLD INDICATION OBSERVED GRADUALLY DECREASING (15 MINS ESTIMATED INTERVAL) FROM FULL THROTTLE SETTING OF 22 INCHES; DETERIORATION CONTINUED TO 17 INCHES. FLT CONDITIONS CLR AND COLD (-10 DEGS C; OUTSIDE AIR TEMP). CARB HEAT APPLIED -- NO RELIEF. FLT INSTS NORMAL -- ALT INDICATING 7500 FT; STABLE. DECISION MADE TO DSND TO WARMER MORE DENSE AIR. DSCNT INITIATED AND DISCOVERED ALL PITOT STATIC INSTS FROZEN IN POS. AIRSPD ZERO. APPLIED PITOT HEAT -- NO IMMEDIATE CHANGE. CONSULTED BOTH GPS'S FOR BACK-UP FLT CONDITIONS AND FOUND ALT INDICATIONS OF ABOUT 11000 FT; GND SPD 89 KTS; OUTSIDE AIR TEMP WAS MUCH COLDER THAN PREVIOUSLY OBSERVED -20 DEGS C. INITIALLY I WAS INCREDULOUS CONCERNING GPS ALT INFO; BUT REALIZED IT ALL ADDED UP. WE HAD CLBED 3500 FT WITHOUT KNOWING IT. OUR ONLY INDICATION OF A PROB WAS DECREASING MANIFOLD INDICATIONS. CORRECTIVE ACTION: INFORMED ZDC OF PROB AND ALT. CONTINUED VFR FLT USING GPS ALT INDICATIONS DSNDING TO 7500 FT WHERE ENG INDICATIONS RETURNED TO NORMAL. ALL PITOT STATIC INDICATIONS REMAINED FROZEN; WITH THE EXCEPTION OF AIRSPD; WHICH STEADILY INCREASED TO FULL SCALE 250 KIAS. FLT COMPLETED TO 0G7 UNEVENTFULLY.
Data retrieved from NASA's ASRS site as of January 2009 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.