A B737 captain was forced to make an emergency stop on taxi out to avoid a collision with a tug.

Attributes
ACN	780674
Time
Date	200804
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 270 flight time type : 9000
ASRS Report	780674
Person 2
Affiliation	company : air carrier
Function	other personnel
Events
Anomaly	conflict : ground critical non adherence : company policies non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	Company
Primary Problem	Company

Narrative:

Tug driver tried to run plane over. Counsel tug crews to be vigilant when operating on airport. Perhaps driver was coming off night shift. Air carrier tug driver did not yield while crossing on vehicle access road. I had to apply full brakes and come to a complete stop from 15-18 KTS. First class passenger saw tug cut in front of us and could not figure out how we missed him.

Original NASA ASRS Text

Title: A B737 CAPT WAS FORCED TO MAKE AN EMERGENCY STOP ON TAXI OUT TO AVOID A COLLISION WITH A TUG.

Narrative: TUG DRIVER TRIED TO RUN PLANE OVER. COUNSEL TUG CREWS TO BE VIGILANT WHEN OPERATING ON ARPT. PERHAPS DRIVER WAS COMING OFF NIGHT SHIFT. ACR TUG DRIVER DID NOT YIELD WHILE XING ON VEHICLE ACCESS ROAD. I HAD TO APPLY FULL BRAKES AND COME TO A COMPLETE STOP FROM 15-18 KTS. FIRST CLASS PAX SAW TUG CUT IN FRONT OF US AND COULD NOT FIGURE OUT HOW WE MISSED HIM.

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