<< >> NASA ASRS Report 190932, September 1991

Flight testing small transport aircraft, encountered severe updraft. Aircraft exceeded assigned altitude 500 causing less than standard separation.

Attributes
ACN	190932
Time
Date	199109
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : atw
State Reference	WI
Altitude	msl bound lower : 5000 msl bound upper : 5500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : grb
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	other personnel other
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 270 flight time total : 17000 flight time type : 400
ASRS Report	190932
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude altitude deviation : overshoot conflict : airborne less severe non adherence : clearance
Independent Detector	other controllera other other : unspecified cockpit
Resolutory Action	flight crew : regained aircraft control flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Filed IFR to 14000 ft to check out pressurization problem (possible cabin leak) cleared to 5000 in rain and moderate turbulence. The pilot was just leveling at 5000 ft and I was checking cabin differential and leaks and felt the aircraft ballooning up with a severe updraft. The pilot was reducing power and pushing controls forward to maintain altitude. The aircraft finally stabilized at 5500 ft and I heard departure control tell him to maintain 5000 ft because of traffic at 6000 and 3 mi away. He descended back to 5000 ft and later was told that the alarm went off and there would be a report filed.

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Original NASA ASRS Text

Title: FLT TESTING SMT ACFT, ENCOUNTERED SEVERE UPDRAFT. ACFT EXCEEDED ASSIGNED ALT 500 CAUSING LTSS.

Narrative: FILED IFR TO 14000 FT TO CHK OUT PRESSURIZATION PROBLEM (POSSIBLE CABIN LEAK) CLRED TO 5000 IN RAIN AND MODERATE TURB. THE PLT WAS JUST LEVELING AT 5000 FT AND I WAS CHKING CABIN DIFFERENTIAL AND LEAKS AND FELT THE ACFT BALLOONING UP WITH A SEVERE UPDRAFT. THE PLT WAS REDUCING PWR AND PUSHING CTLS FORWARD TO MAINTAIN ALT. THE ACFT FINALLY STABILIZED AT 5500 FT AND I HEARD DEP CTL TELL HIM TO MAINTAIN 5000 FT BECAUSE OF TFC AT 6000 AND 3 MI AWAY. HE DSNDED BACK TO 5000 FT AND LATER WAS TOLD THAT THE ALARM WENT OFF AND THERE WOULD BE A RPT FILED.

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.