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A B737-300 flight, while accelerating to 300 KTS, unexpectedly climbs 200 ft above it's level cruise altitude after selecting a lover altitude on the altitude selector on frequency with ZAU, il.
| Attributes | |
| ACN | 523839 |
| Time | |
| Date | 200109 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | intersection : claud |
| State Reference | IL |
| Altitude | msl single value : 2500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc tower : ind.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival star : pmm |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 523839 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Experience | flight time last 90 days : 210 flight time total : 6000 flight time type : 210 |
| ASRS Report | 524022 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other anomaly other |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | flight crew : became reoriented flight crew : overrode automation flight crew : regained aircraft control |
| Consequence | Other |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Aircraft |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
First officer absent from flight deck using facilities. Obtained ATC clearance from FL280 to FL200 at claud intersection at pilot discretion and increase speed from 280K to 320K when able. With autoplt on, altitude was set to 20000 and speed increased to 300K in level flight. Airplane entered an uncommanded climb with the autoplt still engaged. Immediately upon notice of climb, airplane placed into immediate descent, and throttles retarded to idle manually. Descent continued to FL200 at claud and speed then increased to 320K as able first officer returned to flight deck just after descent initiated, and ATC informed of leaving FL280 for FL200 with for present. Supplemental information from acn 524022: approximately 48 plus hours after our flight together, I received a phone call from this particular captain. Told me that on our flight together, he may have deviated from FL280 by 200 ft high just prior to our descent while I was using the bathroom and absent from the cockpit. He also said that at the time of the occurrence, he felt it was a non event and therefore, never bothered to brief me upon my return to the cockpit. Later however, he changed his mind and felt that we should both submit a report on the event that happened.
Original NASA ASRS Text
Title: A B737-300 FLT, WHILE ACCELERATING TO 300 KTS, UNEXPECTEDLY CLIMBS 200 FT ABOVE IT'S LEVEL CRUISE ALT AFTER SELECTING A LOVER ALTITUDE ON THE ALT SELECTOR ON FREQ WITH ZAU, IL.
Narrative: FO ABSENT FROM FLT DECK USING FACILITIES. OBTAINED ATC CLRNC FROM FL280 TO FL200 AT CLAUD INTXN AT PLT DISCRETION AND INCREASE SPEED FROM 280K TO 320K WHEN ABLE. WITH AUTOPLT ON, ALTITUDE WAS SET TO 20000 AND SPEED INCREASED TO 300K IN LEVEL FLT. AIRPLANE ENTERED AN UNCOMMANDED CLIMB WITH THE AUTOPLT STILL ENGAGED. IMMEDIATELY UPON NOTICE OF CLIMB, AIRPLANE PLACED INTO IMMEDIATE DESCENT, AND THROTTLES RETARDED TO IDLE MANUALLY. DESCENT CONTINUED TO FL200 AT CLAUD AND SPEED THEN INCREASED TO 320K AS ABLE FO RETURNED TO FLT DECK JUST AFTER DESCENT INITIATED, AND ATC INFORMED OF LEAVING FL280 FOR FL200 WITH FOR PRESENT. SUPPLEMENTAL INFO FROM ACN 524022: APPROX 48 PLUS HRS AFTER OUR FLT TOGETHER, I RECEIVED A PHONE CALL FROM THIS PARTICULAR CAPT. TOLD ME THAT ON OUR FLT TOGETHER, HE MAY HAVE DEVIATED FROM FL280 BY 200 FT HIGH JUST PRIOR TO OUR DESCENT WHILE I WAS USING THE BATHROOM AND ABSENT FROM THE COCKPIT. HE ALSO SAID THAT AT THE TIME OF THE OCCURRENCE, HE FELT IT WAS A NON EVENT AND THEREFORE, NEVER BOTHERED TO BRIEF ME UPON MY RETURN TO THE COCKPIT. LATER HOWEVER, HE CHANGED HIS MIND AND FELT THAT WE SHOULD BOTH SUBMIT A RPT ON THE EVENT THAT HAPPENED.
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.