Date: 201810
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Second aircraft: B737 Undifferentiated or Other Model
Aircraft component: Nosewheel Steering
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Conflict Ground Conflict; Critical
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Returned To Gate; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After pushing back from gate and successfully taxiing the aircraft around the east concourses; ramp control cleared us [to a different] spot and to contact ground. Shortly before reaching [our new spot] we contacted ground control; and they gave us taxi instructions of Golf; right on [the] runway; hold short of bravo; and contact the other ground control.As I began making the left turn to enter taxiway golf; the tiller locked up. I tried to turn it 2 more times; [I] could feel a grinding at [my] feet; and STEER INOP was displayed. I was unable to reengage steering; and at this point I [was] headed at a stationary at [the spot] that was waiting to turn on to the taxi way after us. I quickly tried steering to the left with the rudders; but found they were locked too. My first reaction was differential power; just to slow the aircraft and avoid advancing toward the [other aircraft]. I deployed full reverse on engine number 1; while advancing power on engine number 2. This attempt at steering was somewhat successful and the aircraft veered left and I was able to bring it to a stop a few feet prior from entering the grass on the right side of taxiway golf. My main concern was avoiding the [other aircraft] in front of me. I brought the aircraft successfully to a stop; informed ground control we were unable to move under our own power; and would require tow. I then made a passenger announcement stating to remain seated and unfortunately we would be returning to the gate. About 20 minutes went by; and a tug showed up; moved us to the West hard stand for approximately 10-15 mins. Then towed us all the way to [the] gate. We deplaned. I called dispatch and maintenance control. The aircraft was unresponsive to all of my control inputs. The nose gear steering mechanism malfunctioned; and became jammed. The whole event lasted less than 30 seconds from detection to aircraft stop. After realizing that [neither] the tiller nor rudder pedals had any authority; my only option left was to use differential reverse/power to veer left and away from the head on aircraft while coming to a stop. We were surrounded by airplanes on all sides and I barely had any time to mitigate the situation.It was a mechanical malfunction.


Second narrative: [Report narrative contained no additional information.]


Synopsis: EMB-145 flight crew reported a near-collision resulted when they lost their nose wheel steering during taxi in a crowded airport environment.