B737 departure from slc is issued abort by ATC because of amass alert.

Attributes
ACN	682495
Time
Date	200512
Place
Locale Reference	airport : slc.airport
State Reference	UT
Altitude	agl single value : 0
Environment
Weather Elements	Rain
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	ground : takeoff roll
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : slc.tower
Operator	common carrier : air taxi
Make Model Name	Caravan 1 208A
Operating Under FAR Part	Part 135
Flight Phase	ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	682495
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	682189
Events
Anomaly	conflict : ground less severe
Independent Detector	atc equipment other atc equipment : amass
Resolutory Action	controller : issued new clearance
Supplementary
Problem Areas	FAA
Primary Problem	FAA

Narrative:

On takeoff roll runway 34L slc; night; light rain; tower called for us to abort the takeoff due to an amass alert. Estimated 110 KTS when abort initiated. Tower later told us that previous arrival traffic (reported a caravan) showed clear of the runway then showed up back on the runway. Neither flight deck crew saw aircraft on takeoff roll though passenger reported seeing the caravan aircraft near side of runway or taxiway. Contributing factors may have been reduced visibility at night with light rain and runway centerline lights out.

Original NASA ASRS Text

Title: B737 DEP FROM SLC IS ISSUED ABORT BY ATC BECAUSE OF AMASS ALERT.

Narrative: ON TKOF ROLL RWY 34L SLC; NIGHT; LIGHT RAIN; TWR CALLED FOR US TO ABORT THE TKOF DUE TO AN AMASS ALERT. ESTIMATED 110 KTS WHEN ABORT INITIATED. TWR LATER TOLD US THAT PREVIOUS ARR TFC (RPTED A CARAVAN) SHOWED CLR OF THE RWY THEN SHOWED UP BACK ON THE RWY. NEITHER FLT DECK CREW SAW ACFT ON TKOF ROLL THOUGH PAX RPTED SEEING THE CARAVAN ACFT NEAR SIDE OF RWY OR TXWY. CONTRIBUTING FACTORS MAY HAVE BEEN REDUCED VISIBILITY AT NIGHT WITH LIGHT RAIN AND RWY CTRLINE LIGHTS OUT.

Data retrieved from NASA's ASRS site as of January 2009 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.