An A319 leaves its assigned altitude of FL370 when it encounters a mountain wave with a subsequent autoplt disconnect when approaching opposite direction traffic, a B747 at FL390 over ALS, co.

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Attributes
ACN	469692
Time
Date	200004
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : als.vor
State Reference	CO
Altitude	msl bound lower : 37000 msl bound upper : 37400
Environment
Flight Conditions	VMC
Weather Elements	other
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : level
Route In Use	enroute airway : ns.airway
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : level
Route In Use	enroute airway : ns.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : instrument pilot : multi engine pilot : cfi pilot : atp
Experience	flight time last 90 days : 180 flight time total : 19000 flight time type : 1400
ASRS Report	469692
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Experience	flight time last 90 days : 180 flight time total : 13000 flight time type : 2000
ASRS Report	469827
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : required legal separation non adherence : clearance other anomaly other anomaly other anomaly other
Independent Detector	atc equipment : conflict alert other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : overcame equipment problem flight crew : regained aircraft control flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 1600
Supplementary
Problem Areas	Environmental Factor Aircraft Weather
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

During cruise we encountered mountain wave just as an airline B747 passed over us at FL390. Due to mountain wave action we had an overspd and the autoplt disconnected and the aircraft left our assigned altitude in a climb. We gained 400 ft before we were able to arrest the climb manually and as a result caused an alert on ZDV's computer. A contributing factor was that we got no aural or visual warning that the autoplt disconnected. Our aircraft was extremely light due to maintenance ferry flight -- approximately 107000 pounds. There was a delayed response by autothrust to overspd condition caused by mountain wave. Factors affecting quality of human performance: A319 automation in normal law prevented us from being able to pitch the nose over to return to FL370 during overspd condition. Supplemental information from acn 469827: aircraft was on autoplt with managed speed (autothrottle). Airspeed increased beyond barber pole. Autoplt kicked off and aircraft started small climb to retard airspeed. After climb of 300-400 ft, I pushed over nose to descend back to FL370. As this was taking place, a B747 was passing overhead at FL390. No TCASII advisory took place.

Original NASA ASRS Text

Title: AN A319 LEAVES ITS ASSIGNED ALT OF FL370 WHEN IT ENCOUNTERS A MOUNTAIN WAVE WITH A SUBSEQUENT AUTOPLT DISCONNECT WHEN APCHING OPPOSITE DIRECTION TFC, A B747 AT FL390 OVER ALS, CO.

Narrative: DURING CRUISE WE ENCOUNTERED MOUNTAIN WAVE JUST AS AN AIRLINE B747 PASSED OVER US AT FL390. DUE TO MOUNTAIN WAVE ACTION WE HAD AN OVERSPD AND THE AUTOPLT DISCONNECTED AND THE ACFT LEFT OUR ASSIGNED ALT IN A CLB. WE GAINED 400 FT BEFORE WE WERE ABLE TO ARREST THE CLB MANUALLY AND AS A RESULT CAUSED AN ALERT ON ZDV'S COMPUTER. A CONTRIBUTING FACTOR WAS THAT WE GOT NO AURAL OR VISUAL WARNING THAT THE AUTOPLT DISCONNECTED. OUR ACFT WAS EXTREMELY LIGHT DUE TO MAINT FERRY FLT -- APPROX 107000 LBS. THERE WAS A DELAYED RESPONSE BY AUTOTHRUST TO OVERSPD CONDITION CAUSED BY MOUNTAIN WAVE. FACTORS AFFECTING QUALITY OF HUMAN PERFORMANCE: A319 AUTOMATION IN NORMAL LAW PREVENTED US FROM BEING ABLE TO PITCH THE NOSE OVER TO RETURN TO FL370 DURING OVERSPD CONDITION. SUPPLEMENTAL INFO FROM ACN 469827: ACFT WAS ON AUTOPLT WITH MANAGED SPD (AUTOTHROTTLE). AIRSPD INCREASED BEYOND BARBER POLE. AUTOPLT KICKED OFF AND ACFT STARTED SMALL CLB TO RETARD AIRSPD. AFTER CLB OF 300-400 FT, I PUSHED OVER NOSE TO DSND BACK TO FL370. AS THIS WAS TAKING PLACE, A B747 WAS PASSING OVERHEAD AT FL390. NO TCASII ADVISORY TOOK PLACE.

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.