Southwest Airlines Boeing 737-79P incident

On June 25, 2024, about 0543 eastern daylight time, Southwest Airlines (SWA) flight 4805, a Boeing 737-79P, N7861J, departed from a closed runway at Portland International Jetport (PWM), Portland, Maine. The flight continued without further incident to its intended destination, Baltimore/Washington International Thurgood Marshall Airport (BWI), Baltimore, Maryland. The 2 flight crewmembers, 3 cabin crewmembers, and 131 passengers deplaned at the gate without any injuries. The flight was operated as a Title 14 Code of Federal Regulations Part 121 scheduled domestic passenger flight.

That same day, the National Transportation Safety Board (NTSB) was notified by SWA about the event and, in response, began an incident investigation. As part of the investigation, the following parties were named: the Federal Aviation Administration (FAA), SWA, Southwest Airlines Pilots Association (SWAPA), and the Boeing Company. The following NTSB specialists were assigned to investigate the incident: Air Traffic Control (ATC), Operations, and Flight Data Recorder (FDR).

History of Flight According to SWA, the incident flight’s dispatch release, titled “release -1,” indicated that the departure time for the flight was 0540. The release also indicated a 12-minute taxi out at PWM and an arrival time at BWI of 0715.

As part of their preflight duties, the flight crew reviewed “Southwest Airlines Briefing” electronic weather packet, which was generated on June 25, 2024, at 0446. The packet contained, in part, the departure and destination weather and, notice to air missions (NOTAMs). There were 32 NOTAMs specifically for PWM, including a NOTAM for runway 11/29 being closed until 0545 on the event date. In addition, part of the weather packet included a content page that included a message that all flights departing from PWM before 0545 must call their dispatcher and receive a briefing from the Chief Pilot who was on call about departing from runway 18/36 which is one of the shortest runways within the SWA system. The flight crew did not see the content page nor did they call for a briefing.

A review of the NOTAMs for PWM revealed that runway 11/29 was closed at the time of the flight’s departure due to construction activities on or near the runway. The runway closure NOTAM was in effect from June 19 to July 24, 2024, and stipulated that the runway would be closed Monday through Friday from 2230 to 0545 and Saturday and Sunday from 0000 to 0545. The incident flight occurred on a Tuesday.

According to the incident flight crew members, they arrived for the flight on time. The captain, who was the pilot flying, began the preflight duties by reviewing the aircraft logbook for open discrepancies, minimum equipment list items, and a maintenance release. The first officer (FO) conducted the exterior preflight duties and programmed their navigation equipment.

The crew used their respective iPads to set up five flight-related applications, including Jeppesen FlightDeck Pro, WSi, and Comply 365, which provided station-specific information.

The captain accessed the Comply 365 application and noted that the PWM tower was closed until 0545; therefore, Boston Air Route Traffic Control Center would need to be contacted on frequency 128.2 for their instrument flight rules (IFR) clearance and void time. The application also indicated that morning departures should expect to use runway 29. The captain stated that he briefed this information to the FO and then entered the departure, destination, and route into the flight management computer.

The flight crew also reviewed the NOTAMs and noted that runway 29 was closed on Saturdays and Sundays until 0545. The captain incorrectly assumed that any additional days for the runway closure would be in the same NOTAM. The flight crew members did not see the separate NOTAM addressing the runway closure on the other days of the week; the NOTAM was underneath another application.

The FO stated that, before pushback, they received performance weight and balance (PWB) takeoff data via AeroData for runway 29. Normally when a runway is closed, no takeoff data is received, only a message stating it is unavailable due to runway closure. The crew did not brief, nor were they required to, the frequency they would utilize. When the flight was ready to push back, the FO advised on the universal communication frequency (UNICOM) frequency 122.95 that they would be pushing back from gate 4. He also advised on the UNICOM frequency they would be taxing to runway 29 for departure. The flight crew completed all briefings and checklists, and the airplane pushed back from the gate normally.

The captain stated that the FO made “multiple calls to Portland Traffic” in regards to their planned taxi route to runway 29. The FO stated, to investigators, that, while taxiing he utilized the UNICOM frequency to announce their intentions. He then, just before reaching the runway, contacted Boston Center and advised that they were number one for departure from runway 29. Boston Center gave a clearance void time with instructions to climb on the runway heading to 4,000 feet. The FO stated that he again advised, over the UNICOM, that the airplane would be turning onto runway 29 for departure. Both crewmembers indicated that they saw a truck exit the runway while the flight was holding short of runway 29. Before applying power, they both confirmed that the truck was clear of the runway; it had turned off the runway onto the taxiway and pulled up by the terminal and faced the runway.

The airplane turned onto runway 29, and the FO announced on UNICOM that the airplane would be departing from runway 29. After a visual check of the runway, the flight crew verified the runway and that it was clear of all objects. The flight crew did not observe any equipment, markings, visual closed runway lighted “Xs” designations, or any other sign indicating that the runway was closed, and all equipment and people were clear of the runway. No other traffic or communication was heard on the UNICOM frequency. The flight departed runway 29 (figure 1) and continued to BWI uneventfully.

Figure 1. SWA flight 4805 departure from runway 29 overlayed on a Google Earth image.

Airport Information PWM is located about 2 miles west of Portland at an elevation of about 76 feet mean sea level. The airport has two paved landing surfaces, 11/29 and 18/36. Runway 11/29 was 7,200 feet long and 150 feet wide.

The PWM air traffic control tower (ATCT) operates from 0545 to 2200 each day. At the time of the incident, the ATCT was closed and not providing services. However, two certified professional controllers (CPC) were in the tower, and one CPC was in the terminal radar approach control.

The airport was equipped with two separate frequencies with which pilots could communicate when the tower was not operating. Those frequencies were listed as the common traffic advisory frequency (CTAF) and UNICOM (see figure 2).

Figure 2. Jeppesen airport diagram for PWM.

Investigative Activities The digital flight data recorder was removed from the SWA airplane and shipped to the NTSB’s Vehicle Recorder Laboratory in Washington, DC, where the data will be downloaded and analyzed.

During the week of July 8, 2024, the operations group interviewed the incident flight crew members and the dispatcher.

The investigation continues.

Verbatim NTSB factual narrative from the NTSB dataset