<< >> NASA ASRS Report 383874, October 1997

A BE36 private pilot suffers a temporary loss of aircraft control as the aircraft executes an altitude excursion in a mountain wave encounter.

Attributes
ACN	383874
Time
Date	199710
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mtj
State Reference	CO
Altitude	msl bound lower : 16000 msl bound upper : 17400
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	general aviation : personal
Make Model Name	Bonanza 36
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute airway : v244 enroute airway : zdv enroute other
Flight Plan	IFR
Aircraft 2
Make Model Name	King Air C90 E90
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 578 flight time total : 1223 flight time type : 1050
ASRS Report	383874
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter other non adherence : clearance other anomaly
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation other

Narrative:

On oct/xx/97, I was on a business-related flight from 00V to 022 on V244 approximately 50 mi west of mtj. My assigned altitude was 16000 ft. Just prior to the occurrence, I was in clear sunshine approaching a dense front of clouds with mountain obscuration and tops appearing to be approximately 20000 ft. Upon entering the clouds, I immediately encountered moderate to severe turbulence and moderate rime icing. The airplane's autoplt was already engaged and holding the airplane at 16000 ft. I requested higher altitude due to rime icing twice, but got no answer. On the third call, I was answered by the controller. I disconnected the autoplt because my airspeed at times exceeded va (design maneuvering speed) and as I was speaking to the controller, I was lifted by an updraft at over 2000 FPM until reaching 17400 ft. After regaining control of the airplane, I requested FL180. The controller stated that it was probably unusable and cleared me to 17000 ft. The controller apparently had oncoming traffic (a king air) which was given a new heading to fly. There was nothing unusual on the remainder of the flight.

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Original NASA ASRS Text

Title: A BE36 PVT PLT SUFFERS A TEMPORARY LOSS OF ACFT CTL AS THE ACFT EXECUTES AN ALT EXCURSION IN A MOUNTAIN WAVE ENCOUNTER.

Narrative: ON OCT/XX/97, I WAS ON A BUSINESS-RELATED FLT FROM 00V TO 022 ON V244 APPROX 50 MI W OF MTJ. MY ASSIGNED ALT WAS 16000 FT. JUST PRIOR TO THE OCCURRENCE, I WAS IN CLR SUNSHINE APCHING A DENSE FRONT OF CLOUDS WITH MOUNTAIN OBSCURATION AND TOPS APPEARING TO BE APPROX 20000 FT. UPON ENTERING THE CLOUDS, I IMMEDIATELY ENCOUNTERED MODERATE TO SEVERE TURB AND MODERATE RIME ICING. THE AIRPLANE'S AUTOPLT WAS ALREADY ENGAGED AND HOLDING THE AIRPLANE AT 16000 FT. I REQUESTED HIGHER ALT DUE TO RIME ICING TWICE, BUT GOT NO ANSWER. ON THE THIRD CALL, I WAS ANSWERED BY THE CTLR. I DISCONNECTED THE AUTOPLT BECAUSE MY AIRSPD AT TIMES EXCEEDED VA (DESIGN MANEUVERING SPD) AND AS I WAS SPEAKING TO THE CTLR, I WAS LIFTED BY AN UPDRAFT AT OVER 2000 FPM UNTIL REACHING 17400 FT. AFTER REGAINING CTL OF THE AIRPLANE, I REQUESTED FL180. THE CTLR STATED THAT IT WAS PROBABLY UNUSABLE AND CLRED ME TO 17000 FT. THE CTLR APPARENTLY HAD ONCOMING TFC (A KING AIR) WHICH WAS GIVEN A NEW HEADING TO FLY. THERE WAS NOTHING UNUSUAL ON THE REMAINDER OF THE FLT.

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.