Bfi tower controller reported a local control trainee sent an aircraft around and issued instruction...

Attributes
ACN	1664791
Time
Date	201907
Local Time Of Day	1201-1800
Place
Locale Reference	BFI.Airport
State Reference	WA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Other Instrument Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Cessna Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Landing Takeoff
Route In Use	None
Flight Plan	VFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 12.5
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Critical Inflight Event / Encounter CFTT / CFIT

Narrative:

Aircraft Y had just departed IFR when approach called us. Aircraft Y was returning VFR with an engine problem. Aircraft Y was about 6 south of the airport at 1200 ft so I decided to [give them priority]. There was another [large transport aircraft] on one mile final aircraft X on about a 12 mile final. I called approach and asked them to break out aircraft X since he was still level at 2200 ft on the ILS. I was trying to make a hole so local west could land aircraft Y on either runway. About one minute later I found out that aircraft X was already on local west frequency. I called approach and asked them for a heading and altitude. At this time aircraft X had started to descend on the ILS but they were still above the MVA (minimum vectoring altitude). There was training on local west at the time and by the time that aircraft X received the heading and altitude instructions they were below the MVA. Aircraft X got as low as 1200 ft before the turn and climb started. The two options were let aircraft X land normally or issue the heading and altitude instructions before they got below the MVA.

Original NASA ASRS Text

Title: BFI Tower controller reported a Local Control Trainee sent an aircraft around and issued instructions below the MVA.

Narrative: Aircraft Y had just departed IFR when Approach called us. Aircraft Y was returning VFR with an engine problem. Aircraft Y was about 6 south of the airport at 1200 ft so I decided to [give them priority]. There was another [large transport aircraft] on one mile final Aircraft X on about a 12 mile final. I called Approach and asked them to break out Aircraft X since he was still level at 2200 ft on the ILS. I was trying to make a hole so Local West could land Aircraft Y on either runway. About one minute later I found out that Aircraft X was already on Local West frequency. I called Approach and asked them for a heading and altitude. At this time Aircraft X had started to descend on the ILS but they were still above the MVA (Minimum Vectoring Altitude). There was training on Local West at the time and by the time that Aircraft X received the heading and altitude instructions they were below the MVA. Aircraft X got as low as 1200 ft before the turn and climb started. The two options were let Aircraft X land normally or issue the heading and altitude instructions before they got below the MVA.

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.

Bfi tower controller reported a local control trainee sent an aircraft around and issued instructions below the MVA.