Altitude deviation.

Attributes
ACN	298696
Time
Date	199503
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : yyc
State Reference	AB
Altitude	msl bound lower : 37700 msl bound upper : 39000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : czeg artcc : zfw
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time total : 23000
ASRS Report	298696
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : unable other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

Mountain wave, standing wave on the east ridge of the canadian rockies near banff -- caused airspeed to mach .87. Altitude dropped to FL377 before aircraft returned to FL390. Autoplt taken off -- high speed buffet. No secondary wave. Reported WX and altitude deviation to edmonton center.

Original NASA ASRS Text

Title: ALTDEV.

Narrative: MOUNTAIN WAVE, STANDING WAVE ON THE E RIDGE OF THE CANADIAN ROCKIES NEAR BANFF -- CAUSED AIRSPD TO MACH .87. ALT DROPPED TO FL377 BEFORE ACFT RETURNED TO FL390. AUTOPLT TAKEN OFF -- HIGH SPD BUFFET. NO SECONDARY WAVE. RPTED WX AND ALTDEV TO EDMONTON CTR.

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.