The NTSB has issued a report detailing a serious incident last month at Chicago O’Hare where an Embraer 170 mistakenly landed on the wrong runway.

On September 25, 2024, American Airlines wholly-owned regional carrier Envoy Air was operating flight 3936 from Norfolk to Chicago O’Hare and touched down on a parallel runway different from its assigned path. The aircraft, with 68 passengers and crew members onboard, landed on runway 10L instead of the designated runway 10C.

American Eagle Embraer E170 at Chicago O’Hare

The incident unfolded amid a sequence of changing runway assignments for the crew. Initially, based on the weather conditions, the pilots planned to land on runway 27R. Air traffic control later informed them to expect runway 9L. Then they were later shifted to 10R before being ultimately assigned to runway 10C as they approached O’Hare. Chicago O’Hare has 8 runways.

Chicago O’Hare

The captain, serving as the pilot monitoring, programmed the flight-management computer to prepare for a visual approach to runway 10C, while also attempting to back up the visual approach with instrument landing system guidance. However, when the crew loaded the ILS for runway 10C, the computer failed to autotune the localizer frequency, and the identifier for the approach did not appear. This prompted the captain to reload the approach and manually input the ILS frequency, but the issue persisted.

ATC directed Flight 3936 to turn onto a 060° heading to align with the localizer for runway 10C. During the communication, the crew initially read back the incorrect heading of 090°, but this was promptly corrected by the approach controller. The pilots were then instructed to maintain a speed of 170 knots and to contact the O’Hare tower controller once they reached the RAYYY waypoint.

Upon establishing contact with the tower, the captain communicated that the aircraft was on a visual approach to runway 10C and was cleared to land. However, due to the unresolved ILS issue and visual misalignment, the aircraft continued its descent toward the adjacent runway, 10L. ATC personnel in the tower identified the discrepancy but chose to coordinate with the controller responsible for runway 10L to permit the landing, as there were no conflicting aircraft in the vicinity.

According to the investigation, neither the crew nor the ATC issued alerts about the alignment error during the approach. The crew did not inform ATC about their inability to receive the localizer for runway 10C, nor did the controllers question the alignment once the aircraft declared itself on a visual approach to 10C.

Chicago O’Hare

The National Transportation Safety Board opened an investigation into the incident, categorizing it as a “serious incident” due to the potential risks involved. The cockpit voice recorder was overwritten after the incident, erasing potentially critical communications and crew decision-making information.

Initial findings highlight multiple contributing factors, including shifting runway assignments, technical difficulties with the ILS autotuning, and communication missteps during the alignment phase. The close proximity of the two parallel runways at O’Hare—runway 10C and runway 10L, separated by just 370 meters—likely compounded the crew’s visual misalignment.

Chicago O’Hare

FAA regulations dictate that controllers should inform pilots if they become aware of an aircraft aligning with an incorrect runway or surface, and issue corrective instructions. It remains unclear why the ATC did not alert the crew to the misalignment in this instance. The investigation remains ongoing.

(HT: Cheryl)