What is DH on Boeing 737? (Decision Height)

Decision Height (DH) is a critical term used in aviation, particularly in the context of aircraft landing procedures. It refers to the altitude at which a pilot must make a decision during an instrument approach to either continue the approach or execute a missed approach. In the case of the Boeing 737, DH plays a crucial role in ensuring the safety of the landing process.

During an instrument approach, pilots use a combination of navigation instruments and visual cues to guide the aircraft to the runway. This is especially important in low visibility conditions, such as during fog or heavy rain. The decision to continue or abort the approach at the decision height is determined based on the pilot’s visual contact with the runway or the approach lights.

Understanding the concept of decision height and its significance on the Boeing 737 is essential for pilots, aviation enthusiasts, and anyone interested in aircraft operations. Let’s explore this topic further and delve into the details of decision height on the Boeing 737.

How is Decision Height Calculated on the Boeing 737?

The decision height on the Boeing 737 is calculated based on several factors, primarily the aircraft’s capability, airport facilities, and weather conditions. The International Civil Aviation Organization (ICAO) sets certain standards and procedures that pilots must follow when determining the decision height during instrument approaches.

To begin with, pilots must take into account the approach category of the aircraft. The approach category is determined based on the aircraft’s approach speed, which is calculated as a percentage of the aircraft’s stall speed. The Boeing 737 has different approach categories, ranging from A to D, with Category D having the highest approach speeds.

Once the approach category is determined, the pilot can refer to the aircraft’s operating manual or performance charts, which provide the required decision height values corresponding to different approach categories. These values are specific to the aircraft’s configuration, weight, and the runway’s characteristics.

Additionally, the airport’s facilities and the available approach aids play a significant role in decision height determination. Runway lighting systems, such as high-intensity runway lights and approach lighting systems, can enhance the pilot’s visibility and help in making accurate decisions during approach. The presence of radar altimeters and advanced navigation equipment also contribute to the calculation of decision height.

Why is Decision Height Important on the Boeing 737?

The decision height on the Boeing 737 is of utmost importance as it directly affects the safety and operational efficiency of the aircraft during landing. By establishing a specific altitude at which the pilot must make a decision, the decision height minimizes the risk of accidents and provides a standardized reference point for pilots across different airports.

The decision height ensures that pilots have adequate visual references to continue the landing approach or initiate a missed approach. If a pilot fails to establish visual contact with the runway or approach lights at the decision height, they are required to execute a missed approach, climbing to a predetermined altitude and following specified procedures to ensure a safe airborne state.

Moreover, decision height allows for consistent and reliable decision-making during instrument approaches. It eliminates guesswork and ensures that pilots have a clear and objective reference point for determining the appropriateness of continuing the approach. This is especially crucial in low visibility conditions, where incorrect decision-making can have severe consequences.

The Role of Automation and Pilot Training in Decision Height Management

The Boeing 737 incorporates advanced automation systems to assist pilots during instrument approaches and decision-making processes. These systems, including the Flight Management Computer (FMC) and Ground Proximity Warning System (GPWS), provide crucial information and alerts to enhance situational awareness and aid in decision height management.

Automation can help pilots accurately calculate the decision height based on the aircraft’s performance characteristics and specific approach procedures. It reduces the likelihood of human errors in decision-making and enhances the overall safety of the landing process.

However, it is important to note that automation does not replace the need for proper pilot training and proficiency. Pilots must undergo comprehensive training on decision height management, including understanding the calculations involved, interpreting the information provided by automation systems, and practicing decision-making scenarios in simulators.

By combining automation and pilot training, the Boeing 737 ensures a robust decision height management system that promotes the safe and efficient operation of the aircraft.


Decision Height is a critical concept in aviation, especially on the Boeing 737. It allows pilots to make informed decisions during instrument approaches and ensures the safety of the landing process. By considering factors such as approach category, airport facilities, and weather conditions, pilots can determine the decision height specific to the Boeing 737. The decision height establishes a standardized reference point for pilots and enhances the consistency and reliability of decision-making across different airports.

Moreover, the Boeing 737’s automation systems, combined with proper pilot training, play a crucial role in decision height management. These systems assist pilots in accurately calculating the decision height and provide important information and alerts during the landing process. However, it is essential to remember that automation does not replace the need for proficient pilot training. Proper training ensures that pilots understand the calculations, interpret automation systems correctly, and make sound decisions based on their training and experience.

Decision height is an integral part of the aircraft’s landing procedures and contributes to the overall safety and efficiency of the Boeing 737. By maintaining a thorough understanding of decision height and its calculations, pilots can confidently navigate instrument approaches and ensure a successful landing.

For More: What is FDAU on Boeing 737? (Flight Data Acquisition Unit)