Altitude deviation altitude excursion during temperature loss of aircraft control.

Attributes
ACN	297889
Time
Date	199503
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : trm
State Reference	CA
Altitude	msl bound lower : 8625 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 15 flight time total : 700 flight time type : 400
ASRS Report	297889
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

Second leg of flight. First leg VFR with heavy turbulence. Refuel, file at barstow/daggett airport. VFR climb to soggi intersection. Numerous frequency changes, delay before IFR pick-up. Again, heavy turbulence until above 7500 ft. Given vectors 120 degrees, then direct psp, then direct trm at 9000 ft. Calm air. Head down on chart. Very abrupt aircraft movement, passenger (daughter) cried out. Felt left roll and pitch up. Heads up, 30 degree left bank, 10 degree pitch. Stall warning horn. Airspeed just below 80 KIAS. Nose down, right rudder, right aileron, climb power. Heading ok, but altitude loss. Vsi scan showed recovery from 1000 FPM down toward level flight -- very slow recovery. Stop descent 8625 ft. Very slow positive rate, recover to 9000 ft assigned. At time of event, received traffic call with request to verify altitude. Informed controller in 'down draft' correcting slowly to 9000. He was initially very distressed but did not further comment. I had been briefed for turbulence, including PIREP from 737 of 'moderate chop' at 11000 ft near trm. By incident time, I had been in at least that for about 2 hours or so. When descent occurred, I had just begun to relax with smooth air. Maintained turbulence air penetration speed just in case which lowered stall margin but may have prevented aircraft damage. The initial pitch up felt like about 2 G. In retrospect, I should have notified the ATC of my situation, but I completely forgot about him in the attempt to control the aircraft. I actually had trouble figuring out what he was talking about when he called because of loss of situational awareness. After I landed and thought about it for several hours, I realized that I had not thought to file a PIREP, which was a significant oversight, as the 737 captain had at least given me some form of warning. I guess I was thinking only of my situation regarding the altitude bust. However, if this had been a fully loaded 172 with a 160 hp engine, instead of a lightly loaded 180 hp model, the descent would have been much further, perhaps with a stall spin situation. In the future, I will reconsider my route of flight when I am briefed about such air conditions in high mountains. Over the desert this was an upset. Over hills, this might have been much worse.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION DURING TEMP LOSS OF ACFT CTL.

Narrative: SECOND LEG OF FLT. FIRST LEG VFR WITH HVY TURB. REFUEL, FILE AT BARSTOW/DAGGETT ARPT. VFR CLB TO SOGGI INTXN. NUMEROUS FREQ CHANGES, DELAY BEFORE IFR PICK-UP. AGAIN, HVY TURB UNTIL ABOVE 7500 FT. GIVEN VECTORS 120 DEGS, THEN DIRECT PSP, THEN DIRECT TRM AT 9000 FT. CALM AIR. HEAD DOWN ON CHART. VERY ABRUPT ACFT MOVEMENT, PAX (DAUGHTER) CRIED OUT. FELT L ROLL AND PITCH UP. HEADS UP, 30 DEG L BANK, 10 DEG PITCH. STALL WARNING HORN. AIRSPD JUST BELOW 80 KIAS. NOSE DOWN, R RUDDER, R AILERON, CLB PWR. HDG OK, BUT ALT LOSS. VSI SCAN SHOWED RECOVERY FROM 1000 FPM DOWN TOWARD LEVEL FLT -- VERY SLOW RECOVERY. STOP DSCNT 8625 FT. VERY SLOW POSITIVE RATE, RECOVER TO 9000 FT ASSIGNED. AT TIME OF EVENT, RECEIVED TFC CALL WITH REQUEST TO VERIFY ALT. INFORMED CTLR IN 'DOWN DRAFT' CORRECTING SLOWLY TO 9000. HE WAS INITIALLY VERY DISTRESSED BUT DID NOT FURTHER COMMENT. I HAD BEEN BRIEFED FOR TURB, INCLUDING PIREP FROM 737 OF 'MODERATE CHOP' AT 11000 FT NEAR TRM. BY INCIDENT TIME, I HAD BEEN IN AT LEAST THAT FOR ABOUT 2 HRS OR SO. WHEN DSCNT OCCURRED, I HAD JUST BEGUN TO RELAX WITH SMOOTH AIR. MAINTAINED TURB AIR PENETRATION SPD JUST IN CASE WHICH LOWERED STALL MARGIN BUT MAY HAVE PREVENTED ACFT DAMAGE. THE INITIAL PITCH UP FELT LIKE ABOUT 2 G. IN RETROSPECT, I SHOULD HAVE NOTIFIED THE ATC OF MY SIT, BUT I COMPLETELY FORGOT ABOUT HIM IN THE ATTEMPT TO CTL THE ACFT. I ACTUALLY HAD TROUBLE FIGURING OUT WHAT HE WAS TALKING ABOUT WHEN HE CALLED BECAUSE OF LOSS OF SITUATIONAL AWARENESS. AFTER I LANDED AND THOUGHT ABOUT IT FOR SEVERAL HRS, I REALIZED THAT I HAD NOT THOUGHT TO FILE A PIREP, WHICH WAS A SIGNIFICANT OVERSIGHT, AS THE 737 CAPT HAD AT LEAST GIVEN ME SOME FORM OF WARNING. I GUESS I WAS THINKING ONLY OF MY SIT REGARDING THE ALT BUST. HOWEVER, IF THIS HAD BEEN A FULLY LOADED 172 WITH A 160 HP ENG, INSTEAD OF A LIGHTLY LOADED 180 HP MODEL, THE DSCNT WOULD HAVE BEEN MUCH FURTHER, PERHAPS WITH A STALL SPIN SIT. IN THE FUTURE, I WILL RECONSIDER MY RTE OF FLT WHEN I AM BRIEFED ABOUT SUCH AIR CONDITIONS IN HIGH MOUNTAINS. OVER THE DESERT THIS WAS AN UPSET. OVER HILLS, THIS MIGHT HAVE BEEN MUCH WORSE.

Data retrieved from NASA's ASRS site as of July 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.