A B737-300 rejected takeoff at 80 KTS due to takeoff warning horn sounding. Cause unknown.

Attributes
ACN	495436
Time
Date	200012
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ewr.airport
State Reference	NJ
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tower : ewr.tower
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	ground : takeoff roll
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time type : 1053
ASRS Report	495436
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : rejected tkof activation other flight crewa other flight crewb
Resolutory Action	flight crew : rejected takeoff
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

As power was advanced by the first officer for takeoff, the takeoff warning horn sounded. There were no visual indications as to why it sounded. The first officer hesitated with the throttle advancement and I reached to make sure the speed brake was down. The horn stopped sounding and we continued the takeoff. I had just made the 80 KT call and the horn sounded again. I slowly reduced the throttles and had not touched the brakes. I was surprised when the rejected takeoff activated a second or two after I reduced the throttles. It engaged for as long as it took me to disengage them. We continued to slow without my applying the brakes and turned off the runway at a slow speed.

Original NASA ASRS Text

Title: A B737-300 REJECTED TKOF AT 80 KTS DUE TO TKOF WARNING HORN SOUNDING. CAUSE UNKNOWN.

Narrative: AS PWR WAS ADVANCED BY THE FO FOR TKOF, THE TKOF WARNING HORN SOUNDED. THERE WERE NO VISUAL INDICATIONS AS TO WHY IT SOUNDED. THE FO HESITATED WITH THE THROTTLE ADVANCEMENT AND I REACHED TO MAKE SURE THE SPD BRAKE WAS DOWN. THE HORN STOPPED SOUNDING AND WE CONTINUED THE TKOF. I HAD JUST MADE THE 80 KT CALL AND THE HORN SOUNDED AGAIN. I SLOWLY REDUCED THE THROTTLES AND HAD NOT TOUCHED THE BRAKES. I WAS SURPRISED WHEN THE REJECTED TKOF ACTIVATED A SECOND OR TWO AFTER I REDUCED THE THROTTLES. IT ENGAGED FOR AS LONG AS IT TOOK ME TO DISENGAGE THEM. WE CONTINUED TO SLOW WITHOUT MY APPLYING THE BRAKES AND TURNED OFF THE RWY AT A SLOW SPD.

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.