Flight crew reported miscommunication with ground crew resulting in a tow breakaway.

Attributes
ACN	1670574
Time
Date	201908
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Commercial Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 91 Flight Crew Total 378 Flight Crew Type 378
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 170 Flight Crew Type 1417
Events
Anomaly	Deviation - Procedural Published Material / Policy Ground Event / Encounter Loss Of Aircraft Control

Narrative:

After leaving gate xx at ZZZ. We were being pushed to spot a. The tug driver stopped momentarily and we heard about a second of static on the radio. The captain asked the tug driver if he said set brakes while simultaneously flashing the lights. At that point the tug and airplane began to move again. I heard a tow bar noise immediately followed by 'breakaway; breakaway'. The captain and I instantly stepped on the brakes. The captain then set the brakes and made sure everyone was ok. After coordinating with ramp crew; maintenance; and operations. We taxied back to the gate.

Original NASA ASRS Text

Title: Flight crew reported miscommunication with ground crew resulting in a tow breakaway.

Narrative: After leaving Gate XX at ZZZ. We were being pushed to spot A. The Tug Driver stopped momentarily and we heard about a second of static on the radio. The Captain asked the Tug Driver if he said set brakes while simultaneously flashing the lights. At that point the tug and airplane began to move again. I heard a tow bar noise immediately followed by 'breakaway; breakaway'. The Captain and I instantly stepped on the brakes. The Captain then set the brakes and made sure everyone was ok. After coordinating with ramp crew; Maintenance; and Operations. We taxied back to the gate.

Data retrieved from NASA's ASRS site 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.