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Unexplained yaw on rotation at liftoff causes concern for crew who requested crash fire rescue equipment monitoring at destination. Uneventful landing with no problems found on inspection.
| Attributes | |
| ACN | 471974 |
| Time | |
| Date | 200004 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : den.airport |
| State Reference | CO |
| Altitude | agl single value : 0 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : den.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | climbout : initial climbout : takeoff landing : roll |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : multi engine pilot : instrument pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 6500 flight time type : 2400 |
| ASRS Report | 471974 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Environmental Factor Aircraft |
| Primary Problem | Ambiguous |
Narrative:
An unusual yaw was felt on takeoff from sacramento. On takeoff, after nosewheel liftoff but before main gear liftoff, aircraft made a single, small, but definite yaw. It did not feel like a normal wind-induced yaw. Gear was left extended until 1500 ft AGL to verify no unusual vibrations were present. Possibilities discussed with all onboard pilot and cabin crew resources, and with company dispatch. All agreed overwhelming probable cause was an unusual wind gust, decision made, however, to conduct a maximum flaps (minimum speed) landing monitored by crash and rescue equipment in the low probability event it had been caused by a deflated tire. Runway at sacramento was also checked for any tire debris. Landing was uneventful and inspection found no problems. Maintenance found nothing wrong during inspection at gate.
Original NASA ASRS Text
Title: UNEXPLAINED YAW ON ROTATION AT LIFTOFF CAUSES CONCERN FOR CREW WHO REQUESTED CFR MONITORING AT DEST. UNEVENTFUL LNDG WITH NO PROBS FOUND ON INSPECTION.
Narrative: AN UNUSUAL YAW WAS FELT ON TKOF FROM SACRAMENTO. ON TKOF, AFTER NOSEWHEEL LIFTOFF BUT BEFORE MAIN GEAR LIFTOFF, ACFT MADE A SINGLE, SMALL, BUT DEFINITE YAW. IT DID NOT FEEL LIKE A NORMAL WIND-INDUCED YAW. GEAR WAS LEFT EXTENDED UNTIL 1500 FT AGL TO VERIFY NO UNUSUAL VIBRATIONS WERE PRESENT. POSSIBILITIES DISCUSSED WITH ALL ONBOARD PLT AND CABIN CREW RESOURCES, AND WITH COMPANY DISPATCH. ALL AGREED OVERWHELMING PROBABLE CAUSE WAS AN UNUSUAL WIND GUST, DECISION MADE, HOWEVER, TO CONDUCT A MAX FLAPS (MINIMUM SPD) LNDG MONITORED BY CRASH AND RESCUE EQUIP IN THE LOW PROBABILITY EVENT IT HAD BEEN CAUSED BY A DEFLATED TIRE. RWY AT SACRAMENTO WAS ALSO CHKED FOR ANY TIRE DEBRIS. LNDG WAS UNEVENTFUL AND INSPECTION FOUND NO PROBS. MAINT FOUND NOTHING WRONG DURING INSPECTION AT GATE.
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.