CommutAir Flight 4933

NTSB narrative

The flight crew of an Embraer EMB145XR airplane was attempting to land on runway 1 at Presque Isle International Airport (PQI), Presque Isle, Maine. Snow was falling at the time. A Notice to Air Mission issued 2 hours 19 minutes before the accident indicated that runway 1 was covered with 1/4 inch of dry snow, and the PQI maintenance foreman stated that the airport had been conducting snow removal operations to maintain that condition on the runway surface.

Accident Sequence

The first instrument landing system (ILS) approach to runway 1 appeared to be proceeding normally until the first officer (the pilot flying) transitioned from instrument references inside the flight deck to outside references. During a postaccident interview, the first officer stated that he expected to see the runway at that time but instead saw “white on white” and a structure with an antenna that was part of the runway environment but not the runway itself. The captain (the pilot monitoring) stated that she saw a tower and called for a goaround. (Both flight crewmembers were most likely seeing the automated weather observing system wind sensor pole, which was located about 325 ft to the right of the runway 1 centerline and about 870 ft beyond the runway threshold, and the damage to the lightning arrester at the top of the wind sensor pole was likely due to contact with the accident airplane as it flew over the pole.) According to the cockpit voice recorder (CVR), after the goaround, the first officer asked the captain if she saw the runway lights during the approach. The captain responded that she saw the lights but that “it’s really white down there that’s the problem.”

Airport personnel stated that snow plowing operations on the runway had finished about 10 minutes before the first approach. The CVR recorded the flight crew’s discussion about turning on the pilot-controlled runway lights and sounds similar to microphone clicks before and after the discussion. However, the PQI maintenance foreman stated that, after the first approach, the runway lights were not on. Thus, the investigation could not determine, based on the available evidence, whether the flight crew had turned on the runway lights during the first approach.

The captain thought that the airplane had drifted off course when the first officer transitioned from flight instruments to the outside, so she instructed the first officer to remain on the instruments during the second approach until the decision altitude (200 ft above ground level [agl]). The second approach proceeded normally with no problems capturing or maintaining the localizer and glideslope. During this approach, the captain asked airport maintenance personnel to ensure that the runway lighting was on, and the PQI maintenance foreman replied that the lights were on “bright”(the high-intensity setting). Thus, the flight crew had a means to identify the runway surface even with the reported snow cover at the time.

As the airplane approached the decision altitude, the captain instructed the first officer to disconnect the autopilot, which he did. About nine seconds later, the airplane reached the decision altitude, and the captain called, “runway in sight twelve o’clock.” This callout was followed by the first officer’s statement, “I’m stayin’ on the flight director ‘cause I don’t see it yet.” A few seconds later, while the airplane was below 100 ft agl, the captain and the first officer expressed confusion, stating “what the [expletive]” and “I don’t know what I'm seein’,” respectively, but neither called for a go-around.

The airplane subsequently impacted the snow-covered grassy area between runway 1 and a parallel taxiway. During a postaccident interview, the first officer stated that, when he transitioned from flight instruments to the outside during the second approach, he again saw “white on white” as well as blowing snow and that the airplane touched down before he could determine what he was seeing. The maintenance foreman estimated that, at the time of the accident, the runway had about 1/8 inch of snow with about 20% to 25% of the runway visible.

Flight Crew Performance

The first officer was relatively new to the EMB145; he received his type rating for the airplane about 7.5 months before the accident. Even though the first officer did not see the runway at the decision altitude, he might have continued the second approach to a landing because he trusted that the captain had the runway in sight. Also, the captain had instructed the first officer to “stay in” multiple times as the airplane descended through 100 ft agl. The captain had apparently intended for the first officer to focus on the flight director and not look outside for the approach lights or the runway.

Company policy stated that the pilot flying should monitor the instruments until the callout “runway in sight” and then transition to outside references no later than 100 ft above the touchdown zone elevation. Company policy also stated that a pilot should call for a goaround if either the runway environment was not in sight by the decision altitude or the successful completion of the approach was in doubt. Thus, when the first officer looked outside after the captain’s “runway in sight” callout and did not see the runway, one or both flight crewmembers should have called for a goaround.

Further, the captain reported that, during the second ILS approach to runway 1, she saw the tower again but explained that the airplane had leveled off to clear the tower before continuing to descend. However, the appearance of the tower should have prompted the captain to call for a go-around, just as she did during the first approach. The captain should have recognized that an airplane that was on the proper vertical and horizontal paths of an ILS approach would not have flown that close to a 30-ft tower while descending below the decision altitude.

The National Transportation Safety Board considered why the flight crew might have continued the second approach rather than call for and perform another go-around, especially since the CVR recorded the captain telling the first officer that, if they did not see the runway during the second approach, they would go to their alternate airport. The CVR also recorded the first officer stating, “if there’s nothing there then we’ll go.” Confirmation bias is a type of cognitive bias that involves a tendency to seek information to support one’s belief instead of information that is contrary to that belief. In this case, the localizer and glideslope information indicated that the airplane was aligned with the runway centerline, and the captain stated that she had the runway in sight. However, the first officer did not have the runway in sight, and both flight crewmembers expressed confusion about what they were seeing outside the airplane when it was below 100 ft agl.

Also, during his previous flight to PQI, the first officer noticed an “incongruency” between the pink needle (providing guidance from the airplane’s flight management system) and the green needle (providing guidance from the ILS localizer signal). Although the first officer shared this information with the captain during the predeparture briefing, neither flight crewmember considered that a navigational air error could be occurring, even though the captain saw a tower (first and second approaches) and the first officer saw a structure with an antenna (first approach). Thus, the crewmembers discounted their confusion about the runway environment and continued the approach likely because of confirmation bias.

The captain was ultimately responsible for the flight. However, she demonstrated poor judgment and decision-making when she instructed the first officer to stay on the flight instruments as the airplane descended below the decision altitude. By the time that the first officer transitioned outside the airplane, not enough time remained for him to determine the airplane’s position in relation to the runway. Although cognitive biases, including confirmation bias, can affect judgment, decisionmaking, and behaviors, a review of the captain’s training records revealed deficiencies regarding her piloting abilities. For example, the CommutAir vice president of flight operations stated that, while the captain was a De Havilland Canada DHC-8 first officer, she received a disciplinary letter and agreed not to pursue captain upgrade training and be monitored for 9 months. Also, in September 2017, the captain received a notice of disapproval from the Federal Aviation Administration (FAA) for her EMB145 type rating. In addition, twice in September 2017, CommutAir placed the captain under “increased scrutiny” due to training failures, including a failed proficiency check. Even though the captain received her EMB145 type rating in early October 2017 and upgraded to captain afterward, her repeated training problems indicated an inadequate foundation for being a captain, which CommutAir did not effectively address.

In addition, although a review of the flight crew’s recent activities determined nothing noteworthy about the captain’s activities and her sleep opportunity (7.5 hours) on the night before the accident, evidence indicated that the first officer was likely fatigued on the day of the accident. Although the first officer stated that he felt rested that day, he had been home with the flu for several days before the accident. Further, the first officer was prescribed a continuous positive airway pressure (CPAP) machine, but he did not consistently use his CPAP between February 26 and March 3, 2019. The daily-use graphic provided in the CPAP download indicated that the first officer used the device for less than 1 hour on February 26, did not use the device between February 27 and March 2, and used the device for about 1 hour 30 minutes between 1200 on March 3 and 1200 on March 4. Due to his illness and lack of CPAP use, the first officer was likely not obtaining adequate sleep during that period.

The first officer commuted to Newark, New Jersey, on the night before the accident. He arrived at a local hotel about 0000 on March 4 due to flight and shuttle delays. The first officer went to sleep about 0100 and awoke about 0600, resulting in a sleep opportunity of 5 hours. The first officer normally slept 7 to 8 hours; thus, he had a sleep debt of about 2 to 3 hours. The quality of his sleep would also have been compromised because he was still coughing and did not use his CPAP. The first officer’s fatigue likely exacerbated the cognitive bias that he experienced during the flight.

Localizer Misalignment

Both flight crewmembers reported that the localizer and glideslope needles were centered during the first and second approaches, indicating that the airplane was aligned with the runway centerline. However, postaccident flight testing of the ILS localizer and glideslope revealed that the localizer was out of tolerance by about 200 ft to the right. After the accident, the airport conducted snow removal operations in the area around and in front of the localizer array; the snow depths (on the day before removal operations began) ranged from about 2 to 5 ft. After the snow was removed, a flight check determined that the localizer signal was in alignment.

About 36 hours before the accident (the night of March 2, 2019), a CommutAir flight crew noted the localizer misalignment while on approach to PQI. After landing, the crew reported the misalignment to a controller at the Boston Air Route Traffic Control Center. The controller reported the localizer misalignment to FAA technical operations personnel, including the center’s operations manager-in-charge, who then informed the center’s National Airspace System operations manager. FAA procedures stated that, for reports of a navigational aid malfunction, air traffic control personnel should request a report from a second aircraft. Because a second pilot report had not yet been received to confirm the localizer misalignment, the National Airspace System operations manager did not act on the initial report about the misalignment. The accident flight was the first instrument flight rules flight to arrive at PQI after the initial report about the localizer misalignment.

FAA procedures for air traffic control personnel also stated that, “in the absence of a second aircraft report, activate the standby equipment or request the monitor facility to activate.” However, PQI did not have an air traffic control tower, and air route traffic control centers, including Boston Center, do not have the capability to activate standby equipment.

Airport personnel at PQI stated that they had no means to determine the alignment of the localizer signal and had to depend on pilot reports. However, the March 2, 2019, pilot report about the localizer misalignment was not provided to airport personnel. In addition, although FAA winter operations guidance contained specific criteria for the allowable snow depth around a glideslope antenna, the guidance did not specify similar information for the area around a localizer antenna array. After the accident, the FAA revised its winter operations guidance to state that snow around a localizer array could affect its radiated signal and that a snow accumulation level of 2 ft was the point at which an FAA ILS specialist would need to begin observing the condition of the localizer signal.

Company Reports of Localizer Misalignment

At least six pilots who flew into PQI during the 5 days before the accident (including the accident first officer) encountered issues with the ILS localizer. However, none of those pilots submitted a company aviation safety action program (ASAP) report before the accident. (Four of the pilots submitted an ASAP report after the accident.) During a postaccident interview, the CommutAir managing director of safety stated that he did not know why the reports were not filed before the accident.

According to the CommutAir director of operations, a company flight data analyst reviewed ASAP reports “right away,” and the analyst provided time-critical information to the appropriate company managers and directors when necessary. Because the reports of the PQI localizer misalignment were submitted after the accident, CommutAir missed an opportunity to make this information available to company flight crews flying to PQI and employ strategies to mitigate any potential threat that the misalignment posed. For example, CommutAir could have alerted those pilots to maintain a heightened awareness of the localizer alignment, restricted the use of the runway 1 ILS approach to higher weather minimums, or prohibited the use of the approach. In addition, if the Boston Air Route Traffic Control Center had received an earlier report of a localizer misalignment, center personnel could have had the opportunity to confirm that report with a second report or take another action to designate the approach as unusable until the localizer signal could be assessed for proper alignment.

Verbatim NTSB analysis and probable cause from the NTSB dataset