What is EO on Boeing 737? (Engine Out)

The Boeing 737 is a widely recognized and relied upon commercial aircraft that has been in service since its introduction in 1967. As with any aircraft, it is of paramount importance to understand the various systems and procedures associated with it, especially in emergency situations, to ensure the safety of passengers and crew. One such significant procedure is the Engine Out scenario or EO, which entails the loss of power in one of the aircraft’s engines. In this article, we will delve into the details of Engine Out on the Boeing 737 and its implications on the aircraft’s performance and operations.

The Effects of Engine Out on Boeing 737

When an aircraft encounters an Engine Out situation, it means that one of its engines has failed or is no longer producing sufficient power to sustain flight. On the Boeing 737, which is typically equipped with two engines, this can significantly impact the aircraft’s performance. Let’s take a closer look at the effects of an Engine Out scenario.

Performance Impacts

1. Reduced Thrust: In an Engine Out situation, the thrust available to the aircraft decreases by 50%, as it is now relying on only one engine to maintain flight. This reduction in thrust has a noticeable impact on the aircraft’s climb performance, cruise speed, and overall maneuverability. Pilots must make immediate adjustments to compensate for this decrease in thrust.

2. Decreased Altitude Capability: With reduced thrust, the Boeing 737’s ability to climb to higher altitudes is significantly compromised. The aircraft may struggle to maintain its current altitude or even have to descend to lower altitudes to maintain a safe and stable flight. This can have implications for the aircraft’s fuel consumption and range.

3. Decreased Range: As a result of the reduced climb performance and limited altitude capability, the range of the Boeing 737 is also affected. The aircraft may not be able to reach the same distances it would under normal operating conditions, impacting its ability to fly long-haul routes without making fuel stopovers.

4. Impaired Maneuverability: Losing an engine on the Boeing 737 also affects the aircraft’s maneuverability. It becomes more challenging for pilots to execute certain maneuvers, such as steep turns or rapid altitude changes. This can have implications on the aircraft’s ability to avoid obstacles or adverse weather conditions.

Emergency Procedures during Engine Out

In the event of an Engine Out situation on the Boeing 737, pilots are trained to follow specific emergency procedures to ensure the safety of everyone on board. Let’s take a closer look at some of these procedures.

1. Identify the Engine Out Condition

The first step for pilots is to quickly identify that an Engine Out condition has occurred. They are trained to recognize the signs and symptoms of an engine failure, such as a sudden loss of power, unusual vibrations, or abnormal engine instrument indications. Once the engine failure is confirmed, the pilots will proceed with the appropriate procedures.

2. Establish Best Glide Speed

After identifying the Engine Out, the pilots must establish the Best Glide Speed for the aircraft. This speed ensures the most efficient glide ratio, allowing the pilots to maintain control and maximize the distance the aircraft can cover while descending. The Best Glide Speed is specific to each aircraft type and is provided in the aircraft’s operating manuals.

It is important to note that the Best Glide Speed is different from the normal cruising speed. The pilots are trained to set the aircraft’s pitch attitude and power settings accordingly to achieve this optimal glide speed.

3. Declare Emergency and Communicate with Air Traffic Control

Once the Engine Out condition is identified and the aircraft is gliding at the Best Glide Speed, the pilots must declare an emergency and communicate with Air Traffic Control (ATC). This ensures that ATC is aware of the situation and can provide necessary assistance, such as prioritizing the aircraft’s landing or helping with navigation to the nearest suitable airport.

Effective communication with ATC is critical during an Engine Out situation, as it allows both the pilots and ATC to work together to ensure a safe outcome. Pilots must relay important information, such as their intentions, fuel status, and any other relevant details that can assist ATC in providing the appropriate guidance.


Understanding the implications and procedures associated with an Engine Out situation on the Boeing 737 is crucial for pilots and aviation enthusiasts alike. It is a testament to the rigorous training and robust design of the aircraft that it can continue to operate safely even in emergency scenarios. By familiarizing ourselves with these scenarios, we can appreciate the complexity of aircraft operations and the extraordinary skill of pilots in handling such situations.

For more information about the Boeing 737 and aviation safety, you can visit Boeing’s official website.

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