Large transport climbing has mild buffet. Requests lower.

Attributes
ACN	250546
Time
Date	199308
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : pmm
State Reference	MI
Altitude	msl bound lower : 38500 msl bound upper : 39000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 540 flight time total : 16000 flight time type : 12000
ASRS Report	250546
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Flight was cleared to climb to FL390. Autoplt was engaged as was altitude select, mach hold and VOR tracking. At about 38700 ft MSL, aircraft began a mild buffet (.80 mach climb speed). Autoplt was disengaged and nose pushed down. At about 38600 ft I attempted to raise nose and climb. Mild buffet (not stick shaker) began again. Nose lowered and at 38500 ft (mach .81) I leveled off and told first officer to get descent clearance to FL350. Controller said no, to maintain FL390. We said we had buffet and needed lower. He responded by clearing us to FL350. No further buffet and a normal flight after. 2 flight attendants at back of aircraft during buffet phase said that one of the engines sounded like it was compressor stalling. Aircraft inspected on ground, all was normal.

Original NASA ASRS Text

Title: LGT CLBING HAS MILD BUFFET. REQUESTS LOWER.

Narrative: FLT WAS CLRED TO CLB TO FL390. AUTOPLT WAS ENGAGED AS WAS ALT SELECT, MACH HOLD AND VOR TRACKING. AT ABOUT 38700 FT MSL, ACFT BEGAN A MILD BUFFET (.80 MACH CLB SPD). AUTOPLT WAS DISENGAGED AND NOSE PUSHED DOWN. AT ABOUT 38600 FT I ATTEMPTED TO RAISE NOSE AND CLB. MILD BUFFET (NOT STICK SHAKER) BEGAN AGAIN. NOSE LOWERED AND AT 38500 FT (MACH .81) I LEVELED OFF AND TOLD FO TO GET DSCNT CLRNC TO FL350. CTLR SAID NO, TO MAINTAIN FL390. WE SAID WE HAD BUFFET AND NEEDED LOWER. HE RESPONDED BY CLRING US TO FL350. NO FURTHER BUFFET AND A NORMAL FLT AFTER. 2 FLT ATTENDANTS AT BACK OF ACFT DURING BUFFET PHASE SAID THAT ONE OF THE ENGS SOUNDED LIKE IT WAS COMPRESSOR STALLING. ACFT INSPECTED ON GND, ALL WAS NORMAL.

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.