Date: 201902
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: A321
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ramp ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Commercial; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Communication Breakdown; Situational Awareness
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Ground Personnel
Result: General Flight Cancelled / Delayed
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: At the end of pushback from the gate; the tug driver directed 'Set Brakes.' I set the brakes; confirmed the brakes were set on the ECAM (Electronic Centralized Aircraft Monitor) and triple indicator and replied 'Brakes Set.' Upon looking outside over the First Officer's shoulder; I realized that we had not been pushed back as far as Ramp Control had requested. I told the tug driver to 'Standby' and not to disconnect the interphone or tow bar. I then consulted with and confirmed with the First Officer that we should be pushed back a bit farther. I then told the tug driver we would need to be pushed back farther. I did not mean to indicate we were ready for the pushback; only that we would; indeed; need to go back farther. He began to push the aircraft again without requesting or ensuring the brakes be released again. The tow bar broke; but caused no aircraft damage. Maintenance inspected the aircraft and the information was noted in the AML (Aircraft Maintenance Log). We continued on to ZZZ1.The pushback entered a nonstandard situation when I set the brake as requested; and said to standby. Usually; only one of those options is used. We either set the brakes or reply to standby. But in this case; since I did not notice our exact position until after setting the brake; I both set the brake and replied to standby and not disconnect. Although correct; given the circumstances; this nonstandard sequence of events precipitated the error. Our Operations Manual does not have a clear procedure on terminology when re-initiating a push that has been interrupted by setting the brakes.From the pilot's perspective; the situation is dependent on the push crew and/or the flight deck crew recognizing that the brakes are set and coordinating a re-release outside of the normal flow of a normal pushback. Additionally; the tug driver and I had a clear miscommunication when I informed him that we needed to be pushed back farther. My intent was not to indicate we were ready to push at that moment; I just intended to inform him of what would be needed and why I had him remain connected. Again; the lack of specific guidance and verbiage for this situation contributed to the miscommunication.I believe a simple procedure/wording could be developed that requires the tug driver to repeat the initial litany requesting brake release prior to all restarts of a pushback after the pushback has been stopped for any reason. Perhaps that is already a requirement; but it is not specifically referenced in the Operations Manual.


Second narrative: Pushed back from gate XX. Our pushback instructions were to push tail north and disconnect nose abeam gate XZ. Tug driver pushed us back and stopped prior to gate XZ and asked us to set the parking brake. Captain did this; and then questioned tug driver that we needed to be pushed back further to abeam gate XZ. Tug driver concurred; and all of a sudden started to push us back without asking us to release the parking brake.We felt some vibration; then the tug driver stopped the push and informed us the tow bar had broken. We contacted Maintenance; got a new tow bar; got towed back to gate XX [and] made an entry in the log. Maintenance inspected the nose gear for damage and none was found. Departed the gate 20 minutes later for an uneventful flight.Nonstandard situation; lack of proper communication on the part of the tug driver. Change procedure/wording to require tug driver to repeat litany requesting brake released prior to all restarts of a pushback.


Synopsis: A321 flight crew reported a communication error during pushback that resulted in a broken tow bar and a delay.