Flight in mountain wave, wind shear.

Attributes
ACN	95146
Time
Date	198809
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bil
State Reference	MT
Altitude	msl bound lower : 400 msl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 50 flight time total : 4408 flight time type : 1700
ASRS Report	95146
Events
Anomaly	inflight encounter : weather other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control
Consequence	other Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

I was returning to great falls, mt, from billings, mt, VFR in our company small transport. I was holding about 800 to 1000' above ground level. I was staying low to avoid the much higher winds at altitude. I hit a wind shear and clear air turbulence with no warning, causing a loss of 400-500'. I was hand flying the aircraft and recovered about 300-400' above the ground and continued with no further problem to my destination. A cold front was about 75 mi north of the incident location. This might have been associated with it or it might have been some type of mountain wave coming from a nearby mountain range. Callback conversation with reporter revealed the following: reporter states terrain was almost level, just a bit rolling with mountains 10-15 mi on either side. Flight was below mountain tops. No injury or aircraft stress occurred. Pilot and passenger really scared because no matter what they did nothing helped. Turbulence was light chop.

Original NASA ASRS Text

Title: FLT IN MOUNTAIN WAVE, WIND SHEAR.

Narrative: I WAS RETURNING TO GREAT FALLS, MT, FROM BILLINGS, MT, VFR IN OUR COMPANY SMT. I WAS HOLDING ABOUT 800 TO 1000' ABOVE GND LEVEL. I WAS STAYING LOW TO AVOID THE MUCH HIGHER WINDS AT ALT. I HIT A WIND SHEAR AND CLEAR AIR TURB WITH NO WARNING, CAUSING A LOSS OF 400-500'. I WAS HAND FLYING THE ACFT AND RECOVERED ABOUT 300-400' ABOVE THE GND AND CONTINUED WITH NO FURTHER PROB TO MY DEST. A COLD FRONT WAS ABOUT 75 MI N OF THE INCIDENT LOCATION. THIS MIGHT HAVE BEEN ASSOCIATED WITH IT OR IT MIGHT HAVE BEEN SOME TYPE OF MOUNTAIN WAVE COMING FROM A NEARBY MOUNTAIN RANGE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATES TERRAIN WAS ALMOST LEVEL, JUST A BIT ROLLING WITH MOUNTAINS 10-15 MI ON EITHER SIDE. FLT WAS BELOW MOUNTAIN TOPS. NO INJURY OR ACFT STRESS OCCURRED. PLT AND PAX REALLY SCARED BECAUSE NO MATTER WHAT THEY DID NOTHING HELPED. TURB WAS LIGHT CHOP.

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