An C172 Instructor pilot and their student reported as they were taxiing the instructor took the controls and turned off the taxiway to avoid another aircraft which had lost control and was head on to them.
Synopsis
An C172 Instructor pilot and their student reported as they were taxiing the instructor took the controls and turned off the taxiway to avoid another aircraft which had lost control and was head on to them.
Narrative
At approximately XA:30 Zulu XB:30 local MST at ZZZ; my student and I were taxiing northbound on taxiway Alpha at ZZZ to Runway XX. Between A4 and Runway X-XY my student and I noticed a 421 Golden Eagle coming towards us at full power. They went off the runway; crossed the grass between the runway and taxiway; crossed over taxiway Alpha; back onto the grass (west of alpha) back onto Alpha at this point they were feet away from us. I took flight control and made the decision to abruptly turn off the taxi way to the east into the grass. The 421 was completely out of control; and at full power about to hit and kill us head on. I committed to the decision to turn right off the taxi way and luckily it just missed us. If I had remained on the taxiway it would have been a very different end to the day. I was extremely surprised at the power and speed the 421 was coming for us. Even if an engine had failed; multi operations call for idling the engines to regain control of the aircraft. The pilot apparently had a very bad attitude; and told the line workers at ZZZ1 jet center to not report the incident.
Second reporter narrative
Chain of events. At the controls of the airplane; I was cleared by ZZZ ground to taxi to Runway XX via Bravo; Alpha; and to cross Runway X-XY. Approximately 150 to 200 ft. after crossing Runway X-XY on Alpha heading northbound I noticed the C421 that had just started its takeoff roll start turning toward us. It was clear he was no longer traveling parallel to the runway and I brought the C172 to a stop and pointed it out to my instructor. We watched the plane accelerate across the grass between the runway and taxiway towards the east. It was obvious that the power was still applied at least to one of the engines although both did appear to be spinning at similar RPM. The plane continued down and then up the dip between the runway and taxiways and continued across the taxiway towards our right. I applied power from a stop and began to turn the plane to the left towards the grass with the goal of putting space between us and the path the C421 was taking. However; it was clear the pilot had little to no control of the airplane. The plane started to turn right back towards and onto the taxiway that we were on still with enough speed that a collision was imminent.My flight instructor took the controls; applied full power and quickly turned our plane to the right and into the grass to avoid the quickly approaching C421. Just as our tail was clear of the taxiway; the C421 passed through the spot we had just been sitting in just 5 seconds earlier at approximately 20-30 kts. Once the C421 had passed we taxied off the grass back onto the taxiway and continued to the run-up area to shut down and inspect the aircraft for damage. No damage was found and we continued my training flight. I want to stress how frightening it was however and although our plane suffered no physical damage the event will have a lasting impact on me which was not fully felt until later that night. It was clear that the pilot had little control of the airplane while crossing over the grasses yet turned back toward us on the taxiway to avoid continuing into the grass/dirt. The dark black tire marks leading off the runway and across the taxiway is evidence that power was still applied across the dirt as the plane was not slowing down and the engine RPM was very high.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.