At the Airport, when Runway 18 is in use, departing aircraft may be instructed intersection departure from E1 without pilotfs consent, however, it is probable that because the PIC A did not know about the procedures, he was required to reconfirm the taxiway.When Aircraft A made incursion into Runway 18 and Aircraft B executed a go-around according to the Towerfs instruction, the distance between Aircraft A and Aircraft B was approximately 3,334 m. The serious incident comes under the severity classification of Category C (An incident characterized by ample time and/or distance to avoid a collision) of gthe Manual on the Prevention of Runway Incursionsh of ICAO with classification tools provided by ICAO. (See Attachment: Severity Classifications of Runway Incursions).