A B737-300 captain reported that the pushback crew used improper disconnect technique in ord.

Attributes
ACN	598927
Time
Date	200311
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	ground : pushback
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 13500 flight time type : 5000
ASRS Report	598927
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : company policies
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	other
Supplementary
Problem Areas	Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

The aircraft was being pushed back from gate. The #1 engine had just completed the start sequence when the aircraft came to a stop. As captain, I heard and felt what I interpreted to be the towbar disconnecting from the aircraft. I looked out my window and observed the push tug backing away from the aircraft. I immediately set the brakes to prevent the aircraft from moving forward under the power of the operating engine. Then the tug driver came on the headset stating he was ready to disconnect. We discussed the fact that he failed to ensure the aircraft brakes were set before he disconnected the towbar. He stated he forgot and thanked me for the reminder. There were no injury or aircraft damage due to this incident.

Original NASA ASRS Text

Title: A B737-300 CAPT RPTED THAT THE PUSHBACK CREW USED IMPROPER DISCONNECT TECHNIQUE IN ORD.

Narrative: THE ACFT WAS BEING PUSHED BACK FROM GATE. THE #1 ENG HAD JUST COMPLETED THE START SEQUENCE WHEN THE ACFT CAME TO A STOP. AS CAPT, I HEARD AND FELT WHAT I INTERPRETED TO BE THE TOWBAR DISCONNECTING FROM THE ACFT. I LOOKED OUT MY WINDOW AND OBSERVED THE PUSH TUG BACKING AWAY FROM THE ACFT. I IMMEDIATELY SET THE BRAKES TO PREVENT THE ACFT FROM MOVING FORWARD UNDER THE PWR OF THE OPERATING ENG. THEN THE TUG DRIVER CAME ON THE HEADSET STATING HE WAS READY TO DISCONNECT. WE DISCUSSED THE FACT THAT HE FAILED TO ENSURE THE ACFT BRAKES WERE SET BEFORE HE DISCONNECTED THE TOWBAR. HE STATED HE FORGOT AND THANKED ME FOR THE REMINDER. THERE WERE NO INJURY OR ACFT DAMAGE DUE TO THIS INCIDENT.

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.