The National Transportation Safety Board has called for urgent action after a series of troubling incidents involving smoke entering the cockpits of Boeing 737 MAX aircraft powered by CFM LEAP-1B engines. The recommendation follows detailed investigations into two specific events from 2023 in which smoke was reported in the flight decks during takeoff or landing, raising serious questions about the operational safety of one of the aviation industry’s most widely used engine types.
The LEAP-1B engine, developed jointly by GE and Safran under the CFM International brand, is a key component in the Boeing 737 MAX fleet. According to investigative findings, the issue arises when birds or foreign objects are ingested into the engine, triggering an automatic function known as a load reduction device. This feature is designed to redirect airflow to stabilize the engine under stress, but it can inadvertently channel smoke into the cockpit through the aircraft’s environmental control system.
The NTSB has now recommended that the Federal Aviation Administration take immediate steps to mandate crew notifications about this risk and evaluate the applicability of the issue to other variants of LEAP engines used on different aircraft models, including Airbus platforms. The agency has also encouraged both CFM and Boeing to continue developing and implementing software modifications aimed at resolving the issue without compromising engine performance or flight safety.
This issue has taken on increased urgency given the widespread use of the 737 MAX across both domestic and international carriers. Airlines that operate the affected aircraft are being asked to review engine maintenance protocols, update pilot training materials, and evaluate potential procedural changes to minimize exposure to smoke hazards during engine anomaly events.
Though the engine's design has passed regulatory certification standards, the NTSB findings highlight the need for dynamic reassessment of aircraft safety protocols, especially as real-world incidents expose vulnerabilities not always evident in laboratory testing. In both 2023 cases under investigation, the crews managed to land safely, but the presence of smoke in the cockpit represented a significant hazard and created stressful conditions that could lead to miscommunication or impaired decision-making under different circumstances.
This latest development adds to the broader scrutiny already surrounding Boeing's 737 MAX platform. The aircraft has faced multiple rounds of regulatory review and public skepticism following its temporary global grounding from 2019 to 2020 due to separate safety issues involving flight control systems. While the MAX was eventually cleared to return to service, these new findings could revive concerns over the thoroughness of safety oversight and quality assurance processes.
For the aviation industry, the situation serves as a reminder of the complexities involved in aircraft engine design and the critical role of feedback loops between operators, regulators, and manufacturers. Pilots and crew members, as frontline stakeholders in flight safety, have welcomed the NTSB’s push for transparency and proactive risk mitigation. The move to alert all operators about the potential for smoke ingress aims to strengthen situational awareness and enhance in-flight safety management practices.
The NTSB’s intervention reflects an appropriate and necessary escalation in the face of repeat incidents involving potential cockpit hazards. While the root technical issue may not indicate a systemic failure in engine design, the consequences of inaction could be severe. Ensuring pilots are properly informed and equipped to manage such scenarios is essential. The recommended review of engine systems and emergency protocols should be pursued with urgency, not only to resolve the existing issue but also to reinforce trust in regulatory vigilance and the robustness of commercial aviation safety standards. The incident underscores the aviation sector’s ongoing challenge of adapting to operational realities while maintaining its exemplary safety record.