Date: 201511
Local time of day: 0001-0600
Location: CNO.Tower, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Landing
Airspace: Class D CNO
ATC / advisory: Tower CNO
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Training / Qualification
Anomaly: Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: In-flight
Contributing factors: Human Factors; Airport; Procedure
Primary problem: Human Factors

Narrative: At the time of the surface incident; I was working Local control. Intersecting Runways are rarely used as the active unless the winds are strong enough to warrant its use. The standard configuration is for west flow. At the time the surface winds were averaging 10 knots out of the southwest I took the position from the Operations Supervisor who was conducting a skills check on a developmental.I had two fixed wing aircraft and one helicopter operating in a closed traffic pattern. While in the right downwind; Aircraft X was cleared for the option with a short approach. At the time; Airport Operations pickup truck was conducting the evening surface inspection and checked in with me holding short of the Runway at the departure end. This was one of my first sessions working the surface inspection on this configuration. I instructed Airport Operations to proceed on to the Runway and turn left at the end. The memory aid stating 'Runway 26R Unavailable' was used. It completely escaped me in the moment that today I needed to restrict the vehicle west of the active Runway. Aircraft X crossed over the threshold of the Runway as Airport Operations was passing through the intersection of the Runways. My scan at the time was focused on sequencing the other two aircraft in the pattern. Ground control noticed the incursion and immediately brought it to my attention as it happened; however the mobile unit was already passed the intersection as Aircraft X was rolling out. The CIC/Supervisor then also became aware of what had transpired and began the necessary reporting procedures. Neither Aircraft X nor mobile unit made any comment of the incident.Both as a trainee and CPC I have had very limited experience on a crossing runway configuration. I would attribute my lapse today mainly to a scan failure and lack of experience working a crossing runway configuration. I am fully aware of aircraft separation requirements on intersecting runways; however when the airport vehicle checked in for the routine inspection I mistakenly reverted to my routine phraseology that I would use any other day for a typical inspection. There are no hold short bars or white edge lines on the Runway and therefore the mobile unit should have been held short of a taxiway. I would stress that the issues surrounding this incident are specific to the routine vehicle surface inspection while intersecting Runways are active. Recommendations I would have to prevent a re-occurrence include:Currently a standard set of phraseology is used in the tower for the daily surface inspection. When intersecting Runways are active; a possible standard operating procedure for the inspection on the parallel runways could include specific instructions. Optimize OJT to include more exposure to crossing runway operations and specific adaptations required for routine events like the surface inspection. Ensure CPCs are provided with sufficient proficiency time on an intersecting Runway configuration. Memory aid that crossing runways are in use (e.g. during the surface inspection) and necessary restrictions need to be provided. Ground control ensures that the airport operations personnel conducting the inspection are aware that intersecting runways are active. Apprising them of the current runway configuration could add a layer of redundancy to protect against future incursions.




Synopsis: CNO Controller allowed a truck to enter a runway for an inspection at the same time as they had an aircraft landing on an intersecting runway.