Date: 202104
Local time of day: 0601-1200
Location: OWD.Airport, MA
Flight conditions: VMC
Weather elements / visibility: 15
Light: Daylight
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Taxi
ATC / advisory: Tower OWD
Second aircraft: Small Aircraft
Reporter organization: Personal
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Commercial
Human factors: Situational Awareness; Distraction; Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Detector: Person Flight Crew
When detected: Taxi
Result: General None Reported / Taken
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: While holding short of Taxiway G on Taxiway C; I witnessed a near miss due to a runway incursion at Taxiway G and the runway. The following is a description of the events that took place: Aircraft X had incurred a flat nose wheel tire at the approach end of the runway on Taxiway C while taxiing for takeoff. Due to Aircraft X blocking the only taxiway to the approach end of the runway; Aircraft Y who was taxiing behind Aircraft X; was forced to execute a 180 degree turn on Taxiway C to enter the runway at Taxiway G and backtrack for departure. Aircraft Y was instructed to hold short of the runway on Taxiway G while I gave way. Instead; Aircraft Y held short of Taxiway G on Taxiway C facing me; whereupon the Tower curtly instructed Aircraft Y to taxi all the way up to and hold short of the runway on Taxiway G. At this time; Aircraft Z was crossing the runway threshold having been cleared to land minutes earlier. Aircraft Y pulled up to and fully across the runway hold short markings; coming within 100 feet of Aircraft Z's left winglet as Aircraft Z touched down. Aircraft Y never came to a full stop after crossing the runway hold short markings and no evasive action by any aircraft were taken. Less than 10 seconds later; having apparently not seen the runway incursion Tower instructed Aircraft Y to backtrack and lineup and wait on Runway 28. No further comments regarding the runway incursion were made by any party.It is likely that Tower was never made aware of the runway incursion; but it is my conclusion that the pilot of Aircraft Y is not the only party at fault. During the course of the events described; it was confusing to determine whether myself or Aircraft Y were number one for departure; due to the fact that Aircraft Y had been forced to execute a 180 on the same taxiway I had been taxiing on in order to reach the runway. Tower in attempting to instruct Aircraft Y pilot that they were number one; was terse in their instructions to fully pull up the runway; ostensibly leading the pilot of Aircraft Y to act quickly and possibly without fully understanding the instructions. The pilot of Aircraft Y should have been more attentive to the situation; understanding that non-standard taxi; takeoff; and landing procedures were being used due to the taxiway blockage and asked for clarification; particularly given the relatively large jet that was touching down. This runway incursion was a wholly preventable incident that could have had deadly consequences.




Synopsis: A pilot taxiing for departure reported observing an aircraft taxi onto the active runway without a clearance as another aircraft was on landing roll.