A controller and a flight instructor reported that an aircraft assigned a vector for one approach in...

Narrative:

The operation was combined in the tower. I was working radar from the d-brite radar display at the local control position. I had just switched an aircraft to the tower on an approach to stay with the tower in closed traffic. I was told from the controller giving me the position that aircraft X was on a 340 heading from the south for the ILS option. I turned aircraft X to a 010 heading then immediately had to use the restroom. I could not wait. The other controller in the tower with me at the time and I made a split second decision to let me run down to the tower break room to use the restroom. I was gone for no more than 3 minutes. When I came back; aircraft X was about a mile west of the airport at 2;400 feet. The controller working the tower tried to transmit to aircraft X but then remembered he did not have the radar frequencies keyed up. I immediately told the pilot to climb to 3;000 feet and to continue on his current heading because there was someone in the pattern. Aircraft X ended up passing behind the aircraft on approach and was well above him. When I asked the student pilot what they were doing they said they were on the VOR-a approach. The instructor pilot keyed up and said they were on the approach but were never given any circling instructions. I told him he was never cleared for an approach to begin with. They eventually made the decision to go back to their departure airport instead of coming back to try another approach.there is no way to prevent this specific situation from happening again; unless a bathroom is put in the tower cab.

Original NASA ASRS Text

Title: A Controller and a flight instructor reported that an aircraft assigned a vector for one approach intercepted and began descent on a different approach. The controller did not immediately notice because they left their control position to go to the bathroom.

Narrative: The operation was combined in the tower. I was working radar from the D-Brite radar display at the Local Control position. I had just switched an aircraft to the tower on an approach to stay with the tower in closed traffic. I was told from the controller giving me the position that Aircraft X was on a 340 heading from the south for the ILS option. I turned Aircraft X to a 010 heading then immediately had to use the restroom. I could not wait. The other controller in the tower with me at the time and I made a split second decision to let me run down to the tower break room to use the restroom. I was gone for no more than 3 minutes. When I came back; Aircraft X was about a mile west of the airport at 2;400 feet. The controller working the tower tried to transmit to Aircraft X but then remembered he did not have the radar frequencies keyed up. I immediately told the pilot to climb to 3;000 feet and to continue on his current heading because there was someone in the pattern. Aircraft X ended up passing behind the aircraft on approach and was well above him. When I asked the student pilot what they were doing they said they were on the VOR-A approach. The instructor pilot keyed up and said they were on the approach but were never given any circling instructions. I told him he was never cleared for an approach to begin with. They eventually made the decision to go back to their departure airport instead of coming back to try another approach.There is no way to prevent this specific situation from happening again; unless a bathroom is put in the tower cab.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1350995
Time
Date	201604
Local Time Of Day	0001-0600
Place
Locale Reference	HSV.TRACON
State Reference	AL
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	DA40 Diamond Star
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 4.0
Person 2
Function	Instructor Pilot Not Flying
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 250 Flight Crew Type 160
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types

A controller and a flight instructor reported that an aircraft assigned a vector for one approach intercepted and began descent on a different approach. The controller did not immediately notice because they left their control position to go to the bathroom.