Delayed takeoff due to unidentified sound in cockpit.

Attributes
ACN	114967
Time
Date	198906
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ict
State Reference	KS
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : jfk
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : takeoff ground : holding
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 154 flight time total : 9025 flight time type : 563
ASRS Report	114967
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

Ready for takeoff at ict, copilot flying. When throttles were advanced heard a howling sound, which we thought was the takeoff warning horn. Copilot closed the throttles and we set the brakes. Flaps, trim, and speed brakes were all set correctly. Ran the power up again and discovered the noise was coming from the center, overhead air conditioning duct. I was surprised at how much it sounded like the warning horn. I closed the duct, which is the normal position for it to keep the noise down. Ran the power up again and the noise was gone. Informed the passenger of the situation, received another takeoff clearance, and made an uneventful takeoff.

Original NASA ASRS Text

Title: DELAYED TKOF DUE TO UNIDENTIFIED SOUND IN COCKPIT.

Narrative: READY FOR TKOF AT ICT, COPLT FLYING. WHEN THROTTLES WERE ADVANCED HEARD A HOWLING SOUND, WHICH WE THOUGHT WAS THE TKOF WARNING HORN. COPLT CLOSED THE THROTTLES AND WE SET THE BRAKES. FLAPS, TRIM, AND SPEED BRAKES WERE ALL SET CORRECTLY. RAN THE POWER UP AGAIN AND DISCOVERED THE NOISE WAS COMING FROM THE CENTER, OVERHEAD AIR CONDITIONING DUCT. I WAS SURPRISED AT HOW MUCH IT SOUNDED LIKE THE WARNING HORN. I CLOSED THE DUCT, WHICH IS THE NORMAL POSITION FOR IT TO KEEP THE NOISE DOWN. RAN THE POWER UP AGAIN AND THE NOISE WAS GONE. INFORMED THE PAX OF THE SITUATION, RECEIVED ANOTHER TKOF CLRNC, AND MADE AN UNEVENTFUL TKOF.

Data retrieved from NASA's ASRS site as of August 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.