Takeoff aborted when takeoff warning horn sounds.

Attributes
ACN	246379
Time
Date	199307
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : cho
State Reference	VA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Transport, High Wing, 2 Turboprop Eng
Navigation In Use	Other Other
Flight Phase	climbout : takeoff other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 250 flight time total : 4600 flight time type : 30
ASRS Report	246379
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : rejected takeoff flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

As the power levers were advanced, the takeoff warning horn sounded. An abort was commanded and executed. We cleared the runway and tried to determine the cause of the horn. All items were set properly for takeoff, however, we suspected the flap position switch may have been close to one of its tolerances and while the correct flap position was selected, indicated and in fact, set, the switch believed them to be otherwise. Flaps were cycled and reset with no other problem no mechanical irregularity apparently existed. A more accurate sensor would probably prevent a recurrence.

Original NASA ASRS Text

Title: TKOF ABORTED WHEN TKOF WARNING HORN SOUNDS.

Narrative: AS THE PWR LEVERS WERE ADVANCED, THE TKOF WARNING HORN SOUNDED. AN ABORT WAS COMMANDED AND EXECUTED. WE CLRED THE RWY AND TRIED TO DETERMINE THE CAUSE OF THE HORN. ALL ITEMS WERE SET PROPERLY FOR TKOF, HOWEVER, WE SUSPECTED THE FLAP POS SWITCH MAY HAVE BEEN CLOSE TO ONE OF ITS TOLERANCES AND WHILE THE CORRECT FLAP POS WAS SELECTED, INDICATED AND IN FACT, SET, THE SWITCH BELIEVED THEM TO BE OTHERWISE. FLAPS WERE CYCLED AND RESET WITH NO OTHER PROB NO MECHANICAL IRREGULARITY APPARENTLY EXISTED. A MORE ACCURATE SENSOR WOULD PROBABLY PREVENT A RECURRENCE.

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.