DC9-51 exercises emergency authority/authorized as buffet occurs at FL350 over per, ok.

Attributes
ACN	453282
Time
Date	199910
Day	Thu
Local Time Of Day	0601 To 1200
Place
State Reference	OK
Altitude	msl bound lower : 31000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 50
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 122 flight time total : 19000 flight time type : 600
ASRS Report	453282
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument pilot : flight engineer
Experience	flight time last 90 days : 4 flight time total : 13200 flight time type : 4
ASRS Report	453283
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance non adherence : far other anomaly other other spatial deviation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : exited adverse environment other
Supplementary
Problem Areas	Aircraft ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft was cleared to FL350. We requested FL310 because too heavy for FL350. After leveling at FL310 for some time, cruising at mach .77 and approximately 285 KIAS, we determined using company charts that we could accept FL350. While climbing through FL340, aircraft performance began to deteriorate and we were climbing at approximately 300 FPM. We leveled at FL35O, but aircraft airspeed continued to deteriorate, at which time we requested lower from ATC. ATC advised us that we couldn't get lower because of opposite direction traffic at FL330. At that time the aircraft began to buffet and we had no choice but to descend. We made a left turn (south) and advised ATC that we were descending. ATC turned the FL330 traffic to their left as well (north) and we continued descent to FL350. No further incident.

Original NASA ASRS Text

Title: DC9-51 EXERCISES EMER AUTH AS BUFFET OCCURS AT FL350 OVER PER, OK.

Narrative: ACFT WAS CLRED TO FL350. WE REQUESTED FL310 BECAUSE TOO HVY FOR FL350. AFTER LEVELING AT FL310 FOR SOME TIME, CRUISING AT MACH .77 AND APPROX 285 KIAS, WE DETERMINED USING COMPANY CHARTS THAT WE COULD ACCEPT FL350. WHILE CLBING THROUGH FL340, ACFT PERFORMANCE BEGAN TO DETERIORATE AND WE WERE CLBING AT APPROX 300 FPM. WE LEVELED AT FL35O, BUT ACFT AIRSPD CONTINUED TO DETERIORATE, AT WHICH TIME WE REQUESTED LOWER FROM ATC. ATC ADVISED US THAT WE COULDN'T GET LOWER BECAUSE OF OPPOSITE DIRECTION TFC AT FL330. AT THAT TIME THE ACFT BEGAN TO BUFFET AND WE HAD NO CHOICE BUT TO DSND. WE MADE A L TURN (S) AND ADVISED ATC THAT WE WERE DSNDING. ATC TURNED THE FL330 TFC TO THEIR L AS WELL (N) AND WE CONTINUED DSCNT TO FL350. NO FURTHER INCIDENT.

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.