Date: 201706
Local time of day: 1201-1800
Location: DVT.Airport, AZ
Flight conditions: VMC
Light: Daylight
Aircraft: PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating under: Part 91
Flight plan: VFR
Mission: Training
Flight phase: Taxi
Airspace: Class D DVT
ATC / advisory: Tower DVT
Second aircraft: PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Developmental
Human factors: Communication Breakdown; Confusion; Training / Qualification; Situational Awareness
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed
Contributing factors: Airport; Aircraft; Company Policy; Procedure; Human Factors; Manuals
Primary problem: Human Factors

Narrative: I was working ground control and was doing my 2-minute overlap after being relieved by the shift supervisor; who was also working the Supervisor position. Aircraft X; a solo student was taxiing to runway 7R was assigned intersection C2 for departure. Aircraft Z; a solo student had landed on runway 7L; cleared at B9; and was holding short of 7R at taxiway B9 on my frequency. Aircraft Y; had also landed 7L; cleared at taxiway B9; and was waiting behind Aircraft Z number 2.During the relief briefing I told the relieving supervisor that Aircraft X was a solo student and taxiing via taxiway C to C2 for departure; and that there were 2 waiting to cross runway 7R at taxiway B9. I pointed to the strips on the board with the callsigns Aircraft Z and Aircraft Y and indicated them as number 1 and number 2 waiting to cross. Per the Standard Operating procedure when the Supervisor position is combined with any other position in the cab and a controller is relieved at any other position in the cab; the controller being relieved is responsible for making the appropriate changes on the Duty board to update the current positions.The relieving supervisor coordinated with the Local South controller to cross runway 7R at B9 with two aircraft; which she approved. I went to the back of the tower cab. I heard the relieving supervisor tell Aircraft X to cross runway 7R at taxiway B9. Aircraft X asked the controller to 'say again.' I then called out that I believed Aircraft X was the one taxiing out for departure. The relieving supervisor did not acknowledge me but again told Aircraft X to cross runway 7R at B9; and Aircraft X read back the instruction. I assumed that since he had the strips in front of him with aircraft callsigns written down that I was confusing Aircraft X and Aircraft Z in my head. The relieving supervisor then told Aircraft Y to cross runway 7R at B9; which he read back.Aircraft Z then called up and told the ground controller he was the one at taxiway B9 holding short of runway 7R. The relieving supervisor then asked Aircraft Z to verify he was number one; which he did. The supervisor then told Aircraft Z to cross runway 7R at B9. I then observed what appeared to be an aircraft departing runway 7R and called out 'is that guy departing?' The Local South controller then started asking who was on the runway and that she had no one departing. Seeing that the C2 intersection was empty I realized that Aircraft X was on runway 7R and taxiing down towards taxiway B9 and said 'that's Aircraft X.' The relieving controller then told Aircraft Z to hold position and once again asked to verify he was at taxiway B9 short of runway 7R; which Aircraft Z answered in the affirmative.I then walked back over to the position; picked up the VFR departure strip for Aircraft X and handed it to the relieving supervisor and; pointing to the aircraft taxiing on the runway; re-emphasized that it was Aircraft X on the runway. The relieving supervisor told Aircraft X that he had taken instructions for the wrong aircraft; instructed him to clear at C5 intersection and later gave Aircraft X the brasher warning.Local South cancelled the crossing coordination and resumed operations. Aircraft Y's clearance to cross runway 7R was never cancelled. No aircraft had to be sent around; there was no immediate safety hazard. The Air Traffic Manager was notified of the incident and; after reviewing the tapes; advised the relieving supervisor that he had used the wrong callsign initially when giving instructions to cross runway 7R.I believe that even though visual aids were provided; the relieving supervisor failed to use them properly and therefore used a similar but incorrect callsign to issue the crossing. I believe that I should have; and will from now on in the future; remain at the position until the overlap is complete before making updates to the Duty Board.




Synopsis: DVT Controller relieved from Ground Control position reported the relieving Supervisor mixed up aircraft call signs and clear two aircraft onto the runway at the same time.