DCA24LA219

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. The flight crew reported that before departure they reviewed the SWA weather packet which included the runway closure notice to airmen (NOTAMs). The captain stated that he reviewed a NOTAM describing weekend runway closures and incorrectly assumed that any additional closure periods would be contained within the same notice. This led the flight crew to believe the runway was not closed at the time of their departure. The flight crew reported that a review of applications on their electronic flight bag (EFB) indicated departures should expect runway 29, and the flight crew was able to receive takeoff performance data. The first officer stated that, under normal circumstances, takeoff performance data would not be provided for a closed runway. Additionally, airport personnel had removed the lighted runway closure “X” markers before the airplane reached the runway, in anticipation of reopening the runway. Consequently, there was no visual indication at the time of departure that the runway was closed. SWA guidance required dispatchers to place a flight lock on affected flights, preventing the release of takeoff performance data and requiring a briefing between the dispatcher, captain, and chief pilot before departure. Due to the nightly closure of PWM runway 11/29, the SWA dispatcher was required to place a flight lock until the required coordination occurred. However, the dispatcher did not place the required Flight Lock on the incident flight, and the flight crew was able to receive takeoff performance data for runway 29 and complete the departure without the required briefing. Had the flight lock been properly implemented, it would have prompted the required discussion and prevented the departure from the closed runway. Lastly, the flight crew used the airport universal communication (UNICOM) frequency rather than the designated common traffic advisory frequency (CTAF) while operating at the uncontrolled airport. Airport operations personnel observed the airplane taxiing for departure and transmitted on CTAF that runway 29 remained closed and would reopen at 0545. Because the crew was not using the proper frequency, they did not receive or respond to this transmission.

Safety Actions SWA reissued the RBD memo following the incident “to emphasize the requirement to lock out all flights scheduled or estimated to arrive or depart PWM between 0230Z (2200 EDT) and 0945Z (0545 EDT) until a call is completed between the Dispatcher, Captain and CPNOC discussing the impact of the runway closure.” PWM is located about 2 miles west of Portland, Maine at an elevation of about 76 ft mean sea level. The airport has two paved landing surfaces, 11/29 and 18/36. Runway 11/29 was 7,200 ft long and 150 ft wide. The PWM air traffic control tower (ATCT) operated from 0545 to 2200 each day. At the time of the incident, the ATCT was closed and not providing services, but 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 CTAF and UNICOM (see figure 2). Figure 2. Jeppesen airport diagram for PWM. When a runway was closed, airport operations personnel placed a mobile lighted “X” at each end of the runway to indicate the runway was unavailable for arrivals and departures. Before reopening the runway each day, operations personnel conducted a runway inspection to verify the absence of personnel, vehicles, equipment, or debris that could pose a hazard to aircraft. On the morning of the incident, airport personnel removed the lighted “X” from the approach end of runway 29, at about 0525, and from the departure end at 0535. After removing the markings and before returning control of the runway to the airport traffic ATCT, operations personnel conducted a runway inspection. The inspection was in progress when the incident flight taxied to the departure end of runway 29. During the inspection, airport operations personnel monitored and broadcast their intentions on the CTAF, a different frequency from the UNICOM frequency. An airport operations vehicle observed the incident airplane taxi toward runway 29 via taxiway A and subsequently broadcast that “runway 29 was closed and would reopen at 0545 local.” The incident flightcrew did not respond to the transmission. The Aeronautical Information Manual (AIM) Section 4-1-9 “Traffic Advisory Practices at Airports without Operating Control Towers,” stated in part: Communicating on a Common Frequency 1. The key to communicating at an airport without an operating control tower is selection of the correct common frequency. The acronym CTAF which stands for Common Traffic Advisory Frequency, is synonymous with this program. A CTAF is a frequency designated for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, MULTICOM, FSS, or tower frequency and is identified in appropriate aeronautical publications. Table 1: Summary of Recommended Communication Procedures (Source: AIM)The CTAF frequency for a particular airport or area is contained in the Chart Supplement U.S., Chart Supplement Alaska, Alaska Terminal Publication, Instrument Approach Procedure Charts, and Instrument Departure Procedure (DP) Charts. Also, the CTAF frequency can be obtained by contacting any FSS. Use of the appropriate CTAF, combined with a visual alertness and application of the following recommended good operating practices, will enhance safety of flight into and out of all uncontrolled airports. The chart supplement for PWM, dated May 16, 2024, through July 11, 2024, listed under the section titled “COMMUNICATIONS” a CTAF frequency of 120.9, an ATIS frequency of 119.05 and a UNICOM frequency of 122.95. The Honeywell solid state flight data recorder (SSFDR) from the incident airplane was sent to the NTSB’s Vehicle Recorder Laboratory in Washington, DC, for analysis. The recorder was in good condition, and the data was extracted normally. The incident flight was the fourth oldest and its duration from engine start to takeoff roll was about 5 minutes and 11 seconds. Data showed that the airplane became airborne with the main gear transitioning from “GND” to “AIR” at about 05:43:04 EDT. On June 25, 2024, about 0543 eastern daylight time, SWA flight 4805, a Boeing 737-79P, N7861J, departed from a closed runway at PWM, Portland, Maine. The flight continued without further incident to its intended destination, Baltimore/Washington International Thurgood Marshall Airport (BWI), Baltimore, Maryland. There was no damage to the airplane nor injuries to the 5 crewmembers and 131 passengers. The flight was operated as a Title 14 Code of Federal Regulations Part 121 scheduled domestic passenger flight. The flight crew stated they arrived on time for the flight. 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 the navigation equipment. As part of their preflight duties, the flight crew reviewed “Southwest Airlines Briefing” electronic weather packet, which was generated that morning at 0446. The packet contained, in part, the departure and destination weather and NOTAMs. There were 32 NOTAMs specifically for PWM, including a NOTAM for runway 11/29 being closed until 0545 on the day of the incident. The crew used their respective EFBs to set up five flight-related applications which provided station-specific information. While accessing his EFB applications, the captain noted that the PWM tower was closed until 0545; therefore, Boston Air Route Traffic Control Center (ARTCC) would need to be contacted 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. At the time of the incident, two separate NOTAMs addressed the closure of runway 29 at certain times of the day due to construction activities on or near the runway. The runway closure NOTAMs were in effect from June 19 to July 24, 2024, and stipulated that runway 11/29 would be closed Monday through Friday from 2230 to 0545 and Saturday and Sunday from 0000 to 0545 (both presented in local time). The flight crew reviewed the NOTAMs and only noted the NOTAM for the closure of runway 29 on Saturdays and Sundays until 0545. In a postincident statement, the captain stated he “incorrectly assumed that any additional days for the runway closure would be in the same NOTAM.” The flight crew stated they did not see the separate NOTAM addressing the runway closure on the other days of the week. The FO stated that, before pushback, they received performance weight and balance (PWB) takeoff data 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. When the flight was ready to push back, the FO advised on the UNICOM frequency 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 that while taxiing he utilized the UNICOM frequency to announce their intentions. Just before reaching the runway, the FO contacted Boston ARTCC and advised that they were number one for departure from runway 29. Boston ARTCC provided a clearance void time with instructions to climb on the runway heading to 4,000 ft. The FO stated that he again advised, over the UNICOM, that the airplane would be turning onto runway 29 for departure. Both flight crew members stated that they saw a truck exit the runway (later determined to be airport operations truck) 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 that the runway 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 at PWM,overlayed on a Google Earth image. Flight Lock A flight lock was a hard-stop control that the dispatcher could use following a dispatch release to ensure any required actions or briefings occurred between the dispatcher and the flight crew before departure. When a flight lock was active it would not allow an operations agent to complete the weight and balance for a flight, the flight crew would not be able to receive takeoff performance data, and the dispatcher would not be able to calculate operational takeoff performance data which would not allow an airplane to push back form the gate. SWA Dispatch Requirements Southwest dispatchers were given guidance via a Southwest Airlines Read Before Dispatch (RBD) memo. The RBD for the nightly closure of PWM runway 11/29 was first issued on April 22, 2024. It was then reissued on April 25, 2024, to update dispatcher action items. One of those action items was to apply a flight lock preventing the release of takeoff performance data and requiring a briefing between the dispatcher, captain, and chief pilot before departure. The RBD memo was then reissued again April 30, 2024, to update the network superintendent action items; however, the RBD still listed the same action items for the dispatcher from the previous issue, including application of a flight lock until the required coordination occurred. After the incident, SWA confirmed that there was no flight lock placed on the incident flight.