(story from AVH, Thanks ! Here's the audio)
https://avherald.com/h?article=5101e4b4&opt=0An Alaska Airlines Boeing 737-800, registration N508AS performing flight AS-1299 from Santa Ana,CA to Portland,OR (USA), was on final approach to Portland's runway 28L when the crew performed a go around from low height about 100 feet AGL due to weather conditions. Tower instructed the Boeing to maintain runway heading and climbed to 3000 feet, which was read back.
At that time a Skywest Airlines Embraer ERJ-175 on behalf of Delta Airlines, registration N304SY performing flight DL-3978 from Portland,OR to Seattle,WA (USA), was accelerating for takeoff from Portland's runway 28R.
After the Embraer became airborne, the controller transmitted the instruction "Skywest 3978, when able start your right turn 340", however, the Boeing read the instruction back (Alaska 1299) and began to turn to the right. Tower upon recognizing the wrong aircraft began to turn right immediately instructed "AS-1299, fly runway heading" followed shortly by "Alaska 1298, fly heading 270" twice, however, without response, the Boeing began to turn left. Tower transmitted traffic information about the Embraer, the Boeing crew acknowledged, now tower again instructed "fly runway heading, maintain 3000 feet" which the crew read back and turned the aircraft back onto the extended runway center line.
The Boeing subsequently diverted to Redmond,OR (USA) for a safe landing, the Embraer continued to Seattle for a safe landing.
The FAA is investigating the occurrence.
According to ADS-B data the separation reduced to about 300 feet vertically and 0.26nm horizontally.
https://www.flightaware.com/live/flight/ASA1299/history/20231016/2110Z/KSNA/KPDXhttps://www.flightaware.com/live/flight/DAL3978/history/20231016/2300Z/KPDX/KSEA
