Modern aviation has transformed the way we connect with the world today. Air travel has made it possible for people to cross continents in a matter of hours, all made possible by the feats of engineering and science. One of the fundamental aspects of commercial aviation is altitude, which plays a crucial role in the safety, efficiency and comfort of passengers.
But have you ever wondered just how high planes can actually fly?
This time, I will explore the world of altitudes in commercial aviation. We’ll look at what altitude means, which factors determine it, the reasons behind flying at high altitudes, the limits of commercial aircraft, and whether a plane can ever fly too high.
What is an altitude?
Altitude in aviation refers to an aircraft’s height above a specific reference point, typically the sea level. It is an essential parameter that pilots need to monitor continuously to ensure safe and efficient flight.
There are several types of altitudes used in aviation, each serving a unique purpose:
Indicated altitude
This is the altitude shown on an aircraft’s altimeter. It is crucial for maintaining proper clearance over obstacles and terrain during takeoff and landing.
True altitude
True altitude is the actual height above mean sea level (MSL). MSL is the average height of the ocean’s surface measured at a specific location over a given period of time. It is calculated by adjusting the indicated altitude for non-standard atmospheric conditions.
Pressure altitude
Pressure altitude is determined by setting the altimeter to a standard atmospheric pressure of 29.92 inches of mercury (inHg) and reading the altitude indicated. This standardization is crucial for consistent and accurate altitude measurements, where it ensures that altitude readings are not affected by variations in atmospheric pressure at different locations and times. Also, it’s essential for flight-level assignments, where aircraft fly at standardized altitudes to ensure separation.
What determines an altitude in an aircraft?
Air pressure and density
Altitude is primarily influenced by the pressure of the surrounding air. As altitude increases, air pressure decreases. Therefore, pilots use altimeters, which measure pressure, to determine their altitude. Changes in air density also affect an aircraft’s performance.
Instruments and systems
Pilots rely on various instruments and systems to maintain and control altitude. These include altimeters, vertical speed indicators and autopilots, which use sensors to provide accurate altitude information.
Altitude changes
During a typical flight, aircraft go through different phases, such as takeoff, cruising and landing. These transitions require adjustments in altitude to ensure a smooth and safe journey.
What determines altitude in general?
Several factors play a role in determining an aircraft’s altitude:
- The aircraft’s type
- The distance covered by the aircraft
- The aircraft’s engine type
- The aircraft’s weight
- Current wind speed
- The direction of travel
- Weather temperature,
- Pilots and air traffic control (ATC) requests
Why do planes fly at high altitudes?
Commercial aircraft are designed to operate at high altitudes for several reasons:
Fuel efficiency
Flying at higher altitudes allows aircraft to take advantage of thinner air, reducing drag and fuel consumption. This results in significant cost savings for airlines.
Speed
At higher altitudes, aircraft can achieve higher true airspeeds due to reduced air resistance, allowing for faster journeys. True speed is the actual speed of an aircraft through the air, accounting for variations in air density and pressure at different altitudes.
Weather avoidance
Flying at high altitudes often places aircraft above turbulent weather, minimizing the risk of weather-related disruptions. This can make for a smoother and more comfortable ride for passengers.
Emergency
In the rare event of an emergency, such as engine failure, a higher altitude offers the pilot more time and options to manage the situation, more time to troubleshoot problems and make decisions.
Traffic and collision avoidance
By flying higher, aircraft can often avoid birds, drones, and smaller aircraft such as light planes and helicopters, which typically operate at lower altitudes.
Also, high altitudes reduce the likelihood of collisions with other aircraft or obstacles, enhancing overall aviation safety.
How high can commercial planes fly?
Commercial aircraft have different maximum operating altitudes, depending on their design and intended use. They typically operate within the range of 30,000 to 42,000 feet, with the universally accepted maximum altitude for commercial airplanes during flight being 42,000 feet.
Private jets can attain even greater altitudes, often exceeding altitudes of 45,000 feet or beyond. Most fighter jets typically operate at altitudes ranging from 45,000 to 51,000 feet.
In comparison, the tallest point on Earth is the summit of Mount Everest, which stands at 8,849 meters (29,032 feet). Beyond 8,000 meters lies the so-called ‘death zone’, where even the most robust climbers can only survive for a few days.
The existing world record for the highest altitude reached by an air-breathing jet-propelled aircraft is 37,650 meters (123,520 feet). This record was established by Alexander Vasilyevich Fedotov while flying a Mikoyan-Gurevich E-266M (MiG-25M) on August 31, 1977.
Can a plane fly too high?
While flying at high altitudes offers many advantages, there are limitations to how high a plane can safely operate at.
One area is known notoriously as the ‘coffin corner’, which represents a dangerous altitude range. The ‘coffin corner’ occurs at the intersection of an aircraft’s low-speed stall limit and its high-speed mach limit, making it challenging to maintain safe flight conditions. Flying in this range can result in severe turbulence and even a stall, which can be extremely hazardous.
For small, non-pressurized jets, flying at high altitudes can pose a risk of hypoxia, a medical condition characterized by a deficiency of oxygen reaching the body’s tissues. It occurs when there is a decreased level of oxygen in the body, leading to inadequate oxygen supply to the cells and organs.
Structural and aerodynamic limitations also impose constraints on an aircraft’s maximum altitude.
So, yes, pushing an aircraft too high could lead to structural damages or even failure, so aircraft manufacturers and regulatory authorities work to establish safe operating limits.
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