Bfi tower controller reported a VFR departure reported a near miss with traffic that had not been po...

Attributes
ACN	1683263
Time
Date	201909
Local Time Of Day	1801-2400
Place
Locale Reference	BFI.Tower
State Reference	WA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	VFR
Aircraft 2
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	VFR
Person 1
Function	Local Trainee
Qualification	Air Traffic Control Developmental
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Conflict NMAC

Narrative:

I started briefing for local east/west position. I was told about aircraft X on a south departure. I took the position. Aircraft Y appeared southbound off a satellite airport climbing. I had to re-verify an arrival's landing clearance due to miscommunication of strip-marking. The event occurred with aircraft X descending to avoid. Aircraft X called stating an aircraft was above them and they had to dive to avoid them. Upon review of the event the conflicting aircraft was aircraft Y turning towards sea for transition. No point out was given. I will continue to work on my scan and remain constantly vigilant about my VFR departures in the case of abnormal situations.

Original NASA ASRS Text

Title: BFI Tower Controller reported a VFR departure reported a near miss with traffic that had not been pointed out to the Controller.

Narrative: I started briefing for Local East/West position. I was told about Aircraft X on a south departure. I took the position. Aircraft Y appeared southbound off a satellite airport climbing. I had to re-verify an arrival's landing clearance due to miscommunication of strip-marking. The event occurred with Aircraft X descending to avoid. Aircraft X called stating an aircraft was above them and they had to dive to avoid them. Upon review of the event the conflicting aircraft was Aircraft Y turning towards SEA for transition. No point out was given. I will continue to work on my scan and remain constantly vigilant about my VFR departures in the case of abnormal situations.

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 VFR departure reported a near miss with traffic that had not been pointed out to the controller.