What happened
On September 25, 2024, at approximately 15:26 CDT, an Envoy Air Embraer 170-100 LR, operating as flight 3936, was conducting a scheduled passenger flight from Norfolk International Airport (ORF) to Chicago O'Hare International Airport (ORD). The flight was cleared for a visual approach to land on runway 10C.
During the descent, the flight crew encountered difficulties with the aircraft's navigation systems. While the captain attempted to troubleshoot the localizer frequency for the ILS approach to runway 10C, the crew was unable to receive the ILS identifier. Consequently, the crew elected to proceed with a visual approach. After contacting the Chicago tower, the crew was cleared to land on runway 10C; however, the aircraft N772MR was aligned with and landed on runway 10L instead. There were no injuries to the 68 occupants, and the aircraft sustained no damage.
The investigation
An investigation into the flight data recorder revealed that for a period of four seconds while flying a heading to intercept the ILS 10C, the Nav 1 radio was correctly tuned to 108.95 MHz. During this brief window, the localizer and glideslope displays indicated the correct course was to the right and above the aircraft. Following this, the Nav 1 radio frequency was changed to 108.4 MHz, and the Nav 2 radio was changed to 113.0 MHz for the remainder of the flight.
Air traffic control records showed that the tower controller noticed the runway alignment error. However, the controller coordinated with the runway 10L controller to allow the landing to proceed because no traffic conflicts were identified. The controller did not notify the crew of the misalignment or issue corrective instructions.
Findings
- The flight crew's misidentification of the intended landing runway led to the landing on the incorrect surface.
- The crew's decision to continue the approach without the correct ILS frequency contributed to the incident.
- The crew was affected by planned continuation bias, a cognitive phenomenon where individuals are unwilling to deviate from a pre-determined course of action despite changing circumstances.
- Air traffic control services were deficient, as the controller failed to notify the flight crew of the alignment error or issue control instructions to prevent the landing on the wrong runway, contrary to FAA directives.