NTSB Report: Envoy Airlines Wrong Runway Landing at Chicago O’Hare

NTSB Final Report: “Plan Continuation Bias” Led to Envoy Airlines Wrong Runway Landing at O’Hare

The National Transportation Safety Board (NTSB) has published its final report regarding a serious incident involving an Envoy Airlines passenger jet at Chicago O’Hare International Airport (ORD). The investigation concludes that a combination of pilot error, technical mismanagement, and air traffic control (ATC) deficiencies led an Embraer 170 to land on the wrong runway on September 25, 2024.

According to the report, released on February 25, 2026, Envoy Airlines flight 3936 (ENY3936) landed safely on Runway 10L despite being cleared for and assigned to Runway 10C. While no injuries or damage occurred to the aircraft (registration N772MR), the NTSB highlights the event as a significant example of “wrong-surface landing” risks, a top safety priority for federal regulators.

The investigation identifies “plan continuation bias” and “expectation bias” as primary psychological factors that caused the flight crew to continue an unstable approach despite lacking critical instrument guidance.

Sequence of Events: Changing Plans and Cognitive Load

The NTSB investigation details a complex arrival phase where the flight crew faced a rapid series of runway assignment changes. These changes likely contributed to a high cognitive workload and “expectation bias” as the crew prepared for landing.

According to the final report, the crew prepared for four different runways in succession due to shifting weather conditions and airport operations:

• Initial Plan: Runway 27R
• First Update: Runway 9L
• Second Update: Runway 10R
• Final Assignment: Runway 10C

The NTSB noted that this sequence of changes forced the crew to repeatedly reprogram the Flight Management System (FMS) and briefing protocols, setting the stage for the errors that followed.

Technical Mismanagement in the Cockpit

Once cleared for a visual approach to Runway 10C, the crew attempted to back up their visual flight path with an Instrument Landing System (ILS) approach to ensure precision. However, the aircraft’s systems failed to “autotune” the correct ILS frequency for Runway 10C.

In an effort to correct the automation failure manually, the captain tuned the navigation radios himself. The investigation revealed a critical error in this process:

“The flight crew’s decision to continue the approach without the correct ILS frequency in the FMS [Flight Management System].”

The report states that the captain manually tuned 108.4 MHz, which was an incorrect frequency, instead of the required 108.95 MHz for Runway 10C. Furthermore, the second radio was tuned to 113.0 MHz, a VOR frequency that provided no vertical or lateral guidance for the landing. Deprived of valid instrument data to verify their alignment, the crew relied entirely on visual cues and inadvertently lined up with Runway 10L, which runs parallel to their assigned runway.

Air Traffic Control Deficiencies

While the primary error originated in the cockpit, the NTSB assigned significant weight to the failure of Air Traffic Control to intervene. The approach controller observed that Envoy flight 3936 was aligned with Runway 10L rather than the assigned 10C.

Under Federal Aviation Administration (FAA) directives, controllers are required to notify pilots immediately if they observe an aircraft aligning with a wrong surface. However, in this instance, the controller did not issue a safety alert or order a go-around. Instead, the approach controller coordinated with the tower controller responsible for Runway 10L to ensure the strip was clear, effectively allowing the error to proceed to a landing.

The NTSB described this decision as “deficient,” noting that it bypassed critical Safety layers designed to prevent collisions.

“Air traffic control’s failure to notify the flight crew that they were lined up with the incorrect runway contrary to FAA directives.”

Probable Cause and Safety Findings

The Board’s final report formally identifies the probable cause of the incident as the crew’s failure to identify the correct runway, driven by psychological biases.

“The flight crew’s misidentification of the intended landing runway, which resulted in an approach to and landing on the wrong runway due to their planned continuation bias.”

The report emphasizes “plan continuation bias”, a phenomenon where pilots continue with an original plan (landing) despite emerging cues that suggest the plan is no longer safe or valid (such as the failure to receive positive ILS guidance). The NTSB also reiterated that wrong-surface landings remain a “top 5” safety focus for the FAA, noting that while this specific incident ended without damage, similar errors have historically led to near-misses and catastrophic collisions.

AirPro News Analysis

This incident serves as a textbook example of how “Swiss Cheese” failure models manifest in modern Aviation. While the pilots made the initial errors, mis-tuning a radio and visually misidentifying a runway, the safety net that is supposed to catch these errors also failed. The ATC decision to silently accommodate the wrong runway landing rather than correct it suggests a potential normalization of deviance in busy terminal environments.

Furthermore, the “expectation bias” noted by the NTSB highlights the vulnerability of human performance during high-workload phases of flight. When runway assignments change four times in a short window, the mental model of the arrival becomes fragmented. For operators, this underscores the importance of “stopping the line”, or initiating a go-around, when automation (like the ILS autotune) behaves unexpectedly, rather than attempting manual workarounds at low altitudes.

Sources

Sources: NTSB Final Report (ID 195210)