Boeing 737-8H4 and Embraer S A ERJ 170-200 LR incident near San Diego, California, June 11, 2021
On June 11, 2021, 2 aircraft, Boeing 737-8H4 (N8674B) and Embraer S A ERJ 170-200 LR (N197SY), were involved in the same incident near San Diego, California (San Diego Intl airport). No one was hurt; 254 people were on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The blocked go-around radio instruction from the air traffic control tower to the arrival aircraft which resulted in the arrival aircraft continuing the landing approach. This led to a loss of separation between the landing aircraft and the aircraft awaiting departure on the runway. Contributing to the loss of separation was the controller’s distraction communicating with a helicopter transitioning the airspace.
The blocked go-around radio instruction from the air traffic control tower to the arrival aircraft which resulted in the arrival aircraft continuing the landing approach. This led to a loss of separation between the landing aircraft and the aircraft awaiting departure on the runway. Contributing to the loss of separation was the controller’s distraction communicating with a helicopter transitioning the airspace.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 11, 2021
- Place
- San Diego, California · San Diego Intl · map
- Type
- Incident
- Injuries
- No one was hurt; 254 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft 1
- Boeing 737-8H4, built 2015 · all 737-8H4s on the register
- Registration
- N8674B · registry record · serial 36734
- Damage
- Not recorded
- Flight
- Flight · scheduled airline rules (Part 121)
- Aircraft 2
- Embraer S A ERJ 170-200 LR, built 2018 · all ERJ 170-200 LRs on the register
- Registration
- N197SY · registry record · serial 17000709
- Damage
- Not recorded
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative for the Boeing 737-8H4 final · quoted from the NTSB record
On June 10, 2021, about 1745 Pacific Daylight Time (PDT) a runway incursion occurred at the San Diego international airport when a SkyWest flight was positioned on Runway 27 for takeoff at the same time a Southwest flight was cleared to land on the same runway. The SkyWest flight was instructed to Line Up and Wait (LUAW) on Runway 27. According to FAA recordings, the Southwest flight was instructed to go around on an approximate 0.84-mile final (about 1.2 miles from the runway 27 displaced threshold); however, the transmission was blocked and the instruction was not heard by the crew. The air traffic control tower controller instructed the SkyWest flight to exit the runway at taxiway C2 about 11 seconds prior to instructing the Southwest flight to go around and to not overfly the SkyWest airplane. The Southwest flight maneuvered around the SkyWest flight exiting the runway and subsequently landed on Runway 27. The closest proximity was 0.18 miles laterally and 200 feet vertically. A review of the FAA audio recordings indicated that the tower controller informed the Southwest flight that there would be traffic holding in position for takeoff on the runway following a preceding arrival aircraft. The controller then issued instructions to other uninvolved aircraft, including a helicopter that was transitioning the airspace. Just after the controller issued instructions for the SkyWest flight to exit the runway, and when the Southwest flight was on an approximate 1.2-mile final, the ASDE-X provided a mandatory go-around alert, and the controller issued go-around instructions to Southwest. The Southwest flight subsequently maneuvered and offset to the left of Runway 27, and then back to the right, and the aircraft aligned with and landed on Runway 27. The SkyWest crew did not hear the air traffic controller’s transmission to the Southwest flight to go around. The SkyWest crew reported they did hear the Southwest flightcrew’s query about the airplane on the runway. According to the FAA, the tower controller was communicating with a helicopter transitioning the airspace after they had instructed SkyWest to LUAW. This additional communication likely distracted the controller from monitoring the position of the SkyWest and Southwest airplanes. Although the FAA reported that tower communication was working normally at the time of the event, they were requested to conduct testing on the strength of the radio signal from the tower cab at various distances away from the airport. However, there was no indication that the FAA was able to conduct such testing and therefore it could not be conclusively determined if the control tower’s frequency strength was adequate to overpower an airborne aircraft’s transmission for other aircraft operating on the airport. Therefore, it is likely that the air traffic controller and the Southwest flightcrew’s simultaneous transmissions canceled each other with no indication to the controller, the arriving aircraft, nor any other aircraft on the frequency.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The NTSB's narrative for the Embraer S A ERJ 170-200 LR final · quoted from the NTSB record
On June 10, 2021, about 1745 Pacific Daylight Time (PDT) a runway incursion occurred at the San Diego international airport when a SkyWest flight was positioned on Runway 27 for takeoff at the same time a Southwest flight was cleared to land on the same runway. The SkyWest flight was instructed to Line Up and Wait (LUAW) on Runway 27. According to FAA recordings, the Southwest flight was instructed to go around on an approximate 0.84-mile final (about 1.2 miles from the runway 27 displaced threshold); however, the transmission was blocked and the instruction was not heard by the crew. The air traffic control tower controller instructed the SkyWest flight to exit the runway at taxiway C2 about 11 seconds prior to instructing the Southwest flight to go around and to not overfly the SkyWest airplane. The Southwest flight maneuvered around the SkyWest flight exiting the runway and subsequently landed on Runway 27. The closest proximity was 0.18 miles laterally and 200 feet vertically. A review of the FAA audio recordings indicated that the tower controller informed the Southwest flight that there would be traffic holding in position for takeoff on the runway following a preceding arrival aircraft. The controller then issued instructions to other uninvolved aircraft, including a helicopter that was transitioning the airspace. Just after the controller issued instructions for the SkyWest flight to exit the runway, and when the Southwest flight was on an approximate 1.2-mile final, the ASDE-X provided a mandatory go-around alert, and the controller issued go-around instructions to Southwest. The Southwest flight subsequently maneuvered and offset to the left of Runway 27, and then back to the right, and the aircraft aligned with and landed on Runway 27. The SkyWest crew did not hear the air traffic controller’s transmission to the Southwest flight to go around. The SkyWest crew reported they did hear the Southwest flightcrew’s query about the airplane on the runway. According to the FAA, the tower controller was communicating with a helicopter transitioning the airspace after they had instructed SkyWest to LUAW. This additional communication likely distracted the controller from monitoring the position of the SkyWest and Southwest airplanes. Although the FAA reported that tower communication was working normally at the time of the event, they were requested to conduct testing on the strength of the radio signal from the tower cab at various distances away from the airport. However, there was no indication that the FAA was able to conduct such testing and therefore it could not be conclusively determined if the control tower’s frequency strength was adequate to overpower an airborne aircraft’s transmission for other aircraft operating on the airport. Therefore, it is likely that the air traffic controller and the Southwest flightcrew’s simultaneous transmissions canceled each other with no indication to the controller, the arriving aircraft, nor any other aircraft on the frequency.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record for the Boeing 737-8H4 from the NTSB's investigation tables, in plain English
What happened, in order
- Runway incursion veh/AC/person during landing
- Comm system malf/failure during approach defining event
- Course deviation during landing
- Air traffic event during landing
- Abrupt maneuver during landing (flare/touchdown)
The NTSB's findings
- Environmental issues › Operating environment › Communication system › VHF/HF radio › Timing of related info
- Environmental issues › Operating environment › Communication system › VHF/HF radio › Ability to respond/compensate
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 23,500 hours in all; 14,500 in this make and model; 110 in the last 90 days; 38 in the last 30 days; 16,000 as pilot in command
- Last flight review: October 1, 2020
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: airline transport pilot, commercial pilot, military
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 8,000 hours in all; 5,500 in this make and model; 230 in the last 90 days; 45 in the last 30 days; 2,500 as pilot in command; 1,600 on instruments
- Last flight review: March 13, 2021
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 19,003 hours
- Last inspection: continuous airworthiness programme, June 9, 2021
- Maximum gross weight: 174,700 lb
- Seats: 185
- Landing gear: retractable
- Engine 1: Cfm Intl CFM56-7B27A (turbofan); 0 hours total
- Engine 2: Cfm Intl CFM56-7B27A (turbofan); 0 hours total
- Operator: Southwest Airlines CO
The flight
- Departed from: KPHX Phoenix AZ at 11:47 pm
- Flight plan: IFR
- Runway 09/2, 9,400 ft by 200 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 300° at 3 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 63°F (17°C), dew point 55°F (13°C)
- Altimeter: 30.01 inHg
- Observation at 11:51 pm from KSAN
Weather report (METAR): KSAN 110651Z 30003KT 10SM CLR 17/13 A3001 RMK AO2 SLP163 T01670128
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 6 | |||
| Passengers | 171 |
The factual record for the Embraer S A ERJ 170-200 LR from the NTSB's investigation tables, in plain English
What happened, in order
- Air traffic event during taxi (from runway)
The NTSB's findings
- Not determined › Not determined › (general) › (general) › Unknown/Not determined
Pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Medical certificate: Unknown
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Seat: rgt
- Injury: no injuries
The aircraft
- Seats: 88
- Landing gear: retractable
- Engine 1: Ge CF34-8E5 (turbofan); 0 hours total
- Engine 2: Ge CF34-8E5 (turbofan); 0 hours total
- Operator: Skywest Airlines INC
The flight
- Destination: SFO San Francisco CA
- Flight plan: IFR
- A second pilot was aboard
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 4 | |||
| Passengers | 73 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number OPS21LA003.