Envoy Air Flight 3936

This incident occurred when the flight crew of Envoy Airlines flight 3936 (ENY3936), an Embraer 170-100 LR, was cleared for a visual approach to land on runway 10C at Chicago O’Hare International Airport (ORD), Chicago, Illinois, however, the flight crew inadvertently landed on runway 10L. While on descent and upon initial check-in with the ORD approach controller, the flight crew was instructed to expect runway 10C. They were subsequently cleared for the instrument landing system (ILS) to runway 10C. The flight crew acknowledged and correctly read back the approach clearance. The flight crew stated that the captain, who was the pilot monitoring, briefed the approach, programmed the flight management computer (FMC) with the ILS approach to runway 10C to back up the planned visual approach. However, they were not receiving the ILS identifier. The captain attempted to troubleshoot why the localizer frequency would not autotune by reloading the approach in the FMC and manually tuning the frequency. Unable to resolve the issue they elected to proceed visually. The captain contacted the air traffic control tower (ATCT) controller stating they were on the visual approach to runway 10C, and the airplane was cleared to land on runway 10C. However, the airplane was aligned with and landed on runway 10L. The flight crew’s decision to continue the approach without the correct ILS frequency was likely affected by their task saturation and planned continuation bias, and their inability to perceive and efficiently integrate available information. Planned continuation bias is an unconscious cognitive phenomenon to continue with the original plan in spite of changing conditions. Once a plan is made and committed to, it becomes increasingly difficult for stimuli or changing conditions to be recognized as necessitating a change to the plan. In addition, as workload increases conditions that may appear obvious to individuals external to the situation are difficult for people caught up in the plan to recognize. Recorded data from the flight data recorder revealed that while flying a heading to intercept the ILS 10C, the localizer frequency in the Nav 1 radio was correctly tuned to 108.95 MHz, the frequency for the ILS 10C localizer, for four seconds. Subsequently, the Nav 1 radio was changed to 108.4 MHz and Nav 2 radio was changed to 113.0 MHz for the remainder of the flight. Although the correct ILS frequency (108.95 MHz) was briefly tuned in the Nav 1 radio, it was subsequently changed to an incorrect frequency (108.4 MHz), and Nav 2 was tuned to a non-ILS frequency (113.0 MHz), preventing the crew from confirming alignment with runway 10C.

The FAA mandatory occurrence report (MOR) revealed that the ATCT controller noticed the runway alignment error and coordinated with the runway 10L controller to allow ENY3936 to land on the incorrect runway as no traffic conflicts were noted. The air traffic control (ATC) services provided by the controller were deficient and contrary to FAA directives. Specifically, the controller failed to notify ENY3936 of their alignment error and did not issue control instructions to prevent the wrong surface landing. Had the controller notified the flight crew of the alignment error or provided control instructions it is likely that the wrong surface landing would have been prevented.

Verbatim NTSB analysis and probable cause from the NTSB dataset