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An air carrier light transport could not maintain a newly assigned higher altitude.
| Attributes | |
| ACN | 252661 |
| Time | |
| Date | 199309 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : vhp |
| State Reference | IN |
| Altitude | msl bound lower : 31000 msl bound upper : 35000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zid |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 210 flight time total : 7500 flight time type : 280 |
| ASRS Report | 252661 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 9500 flight time type : 100 |
| ASRS Report | 252969 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : issued new clearance none taken : anomaly accepted |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Due to turbulence at FL310 we requested a climb to FL350. Our performance charts indicated we would be able to maintain 35000 ft at our existing weight. At 33500 ft center requested us to expedite to FL350. We did this resulting in an airspeed decrease to approximately 230 KIAS. Upon reaching FL350 we were unable to accelerate and in fact began to lose airspeed as well as experience light buffeting. We began an immediate descent calling center 3 times before successfully getting through and receiving a clearance back to FL310. By this time we were at FL340. Contributing causes: our 150 bags in cargo appeared heavier than the 24 pounds/per used for weight and balance calculations. Cockpit temperature information is only in 'RAT' format. Performance charts use static temperatures. Consequently you must convert the 'RAT' to static outside air temperature to utilize the charts. Our conditions were 22 degrees celsius above standard. Supplemental information from acn 252969: with 1000 ft to go, ATC asked us to pick up the rate. I increased the rate from 300 FPM to 500 FPM and lost 10 KTS doing so. At level off, I left the thrust at maximum climb and expected the aircraft to accelerate. To my surprise it began to decelerate and light pre-stall buffet was felt. At just 10 pounds more per passenger and bag, the extra 2700 pounds may have made it impossible to sustain FL350!
Original NASA ASRS Text
Title: AN ACR LTT COULD NOT MAINTAIN A NEWLY ASSIGNED HIGHER ALT.
Narrative: DUE TO TURB AT FL310 WE REQUESTED A CLB TO FL350. OUR PERFORMANCE CHARTS INDICATED WE WOULD BE ABLE TO MAINTAIN 35000 FT AT OUR EXISTING WT. AT 33500 FT CTR REQUESTED US TO EXPEDITE TO FL350. WE DID THIS RESULTING IN AN AIRSPD DECREASE TO APPROX 230 KIAS. UPON REACHING FL350 WE WERE UNABLE TO ACCELERATE AND IN FACT BEGAN TO LOSE AIRSPD AS WELL AS EXPERIENCE LIGHT BUFFETING. WE BEGAN AN IMMEDIATE DSCNT CALLING CTR 3 TIMES BEFORE SUCCESSFULLY GETTING THROUGH AND RECEIVING A CLRNC BACK TO FL310. BY THIS TIME WE WERE AT FL340. CONTRIBUTING CAUSES: OUR 150 BAGS IN CARGO APPEARED HEAVIER THAN THE 24 LBS/PER USED FOR WT AND BAL CALCULATIONS. COCKPIT TEMP INFO IS ONLY IN 'RAT' FORMAT. PERFORMANCE CHARTS USE STATIC TEMPS. CONSEQUENTLY YOU MUST CONVERT THE 'RAT' TO STATIC OUTSIDE AIR TEMP TO UTILIZE THE CHARTS. OUR CONDITIONS WERE 22 DEGS CELSIUS ABOVE STANDARD. SUPPLEMENTAL INFO FROM ACN 252969: WITH 1000 FT TO GO, ATC ASKED US TO PICK UP THE RATE. I INCREASED THE RATE FROM 300 FPM TO 500 FPM AND LOST 10 KTS DOING SO. AT LEVEL OFF, I LEFT THE THRUST AT MAX CLB AND EXPECTED THE ACFT TO ACCELERATE. TO MY SURPRISE IT BEGAN TO DECELERATE AND LIGHT PRE-STALL BUFFET WAS FELT. AT JUST 10 LBS MORE PER PAX AND BAG, THE EXTRA 2700 LBS MAY HAVE MADE IT IMPOSSIBLE TO SUSTAIN FL350!
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.