What is ALT on Boeing 737? (Altitude)

Altitude, often represented by the abbreviation ALT, is a crucial concept in aviation, including on the Boeing 737 aircraft. It refers to the vertical distance of an aircraft above a specific point, usually measured in feet. Altitude plays a significant role in various aspects of flight, from navigation and communication to safety and fuel efficiency. In this article, we will explore the importance of altitude on the Boeing 737 and delve into its impact on the aircraft’s performance and operations.

The Role of Altitude in Efficient Flight

Altitude is a critical factor in achieving efficient flight operations on the Boeing 737 aircraft. By flying at higher altitudes, pilots can take advantage of various aerodynamic factors that enhance fuel efficiency and reduce operating costs.

One key advantage of flying at higher altitudes is the reduction in air density. As an aircraft climbs to higher altitudes, the air becomes less dense, resulting in lower drag and better fuel efficiency. This allows the Boeing 737 to cover more distance with the same amount of fuel, making it a cost-effective choice for airlines.

Furthermore, flying at higher altitudes allows the Boeing 737 to take advantage of favorable tailwinds. Winds at higher altitudes often blow in the same direction as the desired flight path, providing an additional boost to the aircraft’s groundspeed. This not only reduces the total flight time but also saves fuel by reducing the time spent in the air.

Altitude Restrictions and Limitations

While altitude offers numerous advantages, there are also restrictions and limitations that must be considered when operating the Boeing 737 aircraft.

The maximum operating altitude for the Boeing 737 varies depending on the specific model. For example, the Boeing 737-800 has a maximum operating altitude of 41,000 feet, while the newer Boeing 737 MAX 8 can operate up to 41,000 feet as well. These altitude limits are determined by factors such as engine performance, cabin pressurization capabilities, and structural limitations.

Another important consideration when operating at higher altitudes is the availability of oxygen. As altitude increases, the air becomes thinner and the amount of oxygen decreases. Therefore, it is vital to ensure the availability of supplemental oxygen for crew members and passengers, especially during extended flights at higher altitudes.

Factors Influencing Altitude Selection

The selection of an optimal altitude for a Boeing 737 flight is influenced by several factors, including distance, weather conditions, and air traffic control instructions.

First and foremost, the distance to be covered is a significant determinant of the altitude selection. For shorter flights, pilots may choose to fly at lower altitudes to minimize climb and descent times, especially when there are no fuel efficiency advantages associated with higher altitudes.

The prevailing weather conditions also play a crucial role in altitude selection. Pilots need to consider factors such as turbulence, cloud cover, and icing conditions to ensure a safe and comfortable flight. In some cases, flying at higher altitudes may provide smoother air conditions by avoiding adverse weather patterns.

Air traffic control instructions also dictate the altitude that a Boeing 737 must maintain during different stages of flight. These instructions are aimed at ensuring safe separation between aircraft and efficient traffic management. Pilots must comply with these instructions while taking into account their fuel efficiency objectives and constraints.


Altitude, denoted by the abbreviation ALT, holds significant importance in the operations of the Boeing 737 aircraft. It directly affects fuel efficiency, flight duration, and the overall performance of the aircraft. Pilots carefully consider altitude selection while accounting for weather conditions, distance, and air traffic control instructions. By optimizing altitude, the Boeing 737 can achieve efficient and cost-effective flight operations, benefiting both airlines and passengers.

For More: What is CCM on Boeing 737? (Cargo Control Module)