If there is one thing you may notice when flying on a turboprop aircraft compared to a jet aircraft, it’s that you don’t fly as high in a turboprop. I remember my first plane ride from Manila to Baguio in 1987 on an HS748; it was easy to identify some landmarks below, but when you are flying high in a jet, it’s different. Hence, yes, to those wondering, turboprop planes cannot fly as high as jets. While commercial jet airliners typically fly between 32,000 and 42,000 feet, turboprop airplanes usually cruise at lower altitudes.
A De Havilland Canada DHC Dash 8-400 has a maximum service ceiling of 27,000 feet. An ATR 72-500 typically has a service ceiling of 25,000 feet. The turboprop commercial aircraft with the highest service ceiling ever was the Russian-built Tupolev Tu-114, with a service ceiling of 39,000 feet. The Tu-114 is no longer in commercial service.
The Mechanics of Turboprop Airplanes
To grasp why turboprop airplanes fly at lower altitudes, it’s essential to understand what a turboprop airplane is. Turboprop airplanes are powered by one or more propeller-driven engines. These engines, known as turboprops, consist of an air intake, compressor, combustion chamber, propelling nozzle, turbine, and a set of gears connecting to a propeller. While the propelling nozzle does provide some thrust, the majority of the thrust in a turboprop engine comes from the propeller.
Most turboprop airplanes typically fly at altitudes ranging from 25,000 to 30,000 feet above ground or sea level. While there are exceptions, this range is the average cruising altitude for a standard turboprop airplane.
Why Turboprops Fly Lower
One of the primary reasons turboprop airplanes fly at lower altitudes is their lack of benefit from the cold, less dense air found at higher altitudes. Jet airplanes, such as those powered by turbofans, use the cold and thin air at high altitudes to their advantage, achieving less drag and greater efficiency. This advantage is not as pronounced in turboprop airplanes.
The design of propellers plays a role in the altitude limitations of turboprop airplanes. Propellers are engineered to cut through the air, displacing the surrounding air as they turn, which propels the airplane forward. However, propellers are less effective at high altitudes due to decreasing air density. As an airplane ascends, the air becomes thinner, posing a challenge for the propeller to produce sufficient thrust. The reduced air density at higher altitudes means that even if the propeller turns, it displaces less air, resulting in decreased propulsion.
Turbulence and Weather Susceptibility
Flying at lower altitudes means turboprop airplanes are more susceptible to turbulence and adverse weather conditions. This is a trade-off for the type of efficiency and functionality that turboprop engines offer. While they may not reach the lofty heights of commercial jetliners, turboprop airplanes are designed to operate optimally within their altitude range, providing a balance of efficiency and performance suited to their design.
Turboprop airplanes are optimized for lower cruising altitudes compared to jet-powered commercial airliners. The interplay of cold air benefits, propeller efficiency, and air density dictates their operational ceiling. And this is why turboprops normally do not fly as high as jets.
First love never dies. I fell in love with airplanes and aviation when I was a kid. My dream was to become a pilot, but destiny led me to another path: to be an aviation digital media content creator and a small business owner. My passion for aviation inspires me to bring you quality content through my website and social accounts. Aviation is indeed in my blood and blog!
