Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors
We had just pushed off of [the] gate in PHL and were completing the After Start Checklist. The nose of the aircraft was still facing the gate (west) when I noticed a company aircraft making its way around the corner of the north side of the ramp turning southbound and headed toward us. Once we were ready to taxi I called for taxi instructions. Ramp didn't mention anything about the traffic behind us and I did not find that to be out of the ordinary. I assumed the aircraft was going to give way to us since our tail was partly blocking their path. As we made the left hand turn toward my Captain upgrade having a better view first noticed that the oncoming aircraft was not giving way to us. He immediately stopped the aircraft and we watched as [the other aircraft] came dangerously close to us. I made a call to the aircraft over the ramp frequency however they did not hear as they had already switched over to ground frequency.Poor judgment on the part of [the other flight crew] to continue taxiing with a moving aircraft in front of them; that was clearly taxiing out and not parking at the gate. I personally spoke with the Captain of that flight and he said he knew we were taxiing out but assumed we were just turning the airplane. Even if this were the case there would not have been a sufficient margin of space between the aircraft. He also admitted that he didn't know we'd been given taxi instructions from ramp meaning they switched to ground frequency far too early; losing situation awareness to the movement of other aircraft on the ramp.[The other flight crew] claims that ramp didn't tell them about us however I don't find that to be the problem. Seeing us in front of them [they] should have given way and not pushed through next to a moving aircraft. They had full view of us however we had no view of them until the last minute. Ramp could have paid a little more attention as well to tell the other aircraft to give way; or held our taxi instructions until they'd passed.
Medium Transport Captain reported a near collision on the ramp at PHL.