Have you ever gazed up at a plane soaring through the sky and wondered, “How fast is that thing actually going?” It’s a question that sparks curiosity in many, from frequent flyers to aviation enthusiasts. The straightforward answer is that the average cruising speed of a commercial airliner typically ranges from 880 to 926 kilometers per hour (km/h), which translates to about 475 to 500 knots or 547 to 575 miles per hour (mph).
However, pinning down a single speed for commercial airliners is like trying to catch a cloud – it’s more complex than it first appears. Numerous factors come into play that dictate just how fast these metal birds can fly. Before we delve into these fascinating elements, let’s take a look at the typical cruising speeds of some popular commercial aircraft:
Cruising Speeds of Common Commercial Aircraft
To give you a clearer picture, here’s a table outlining the cruise speeds of various common commercial airplanes. Speeds are provided in Mach number, knots, and mph for a comprehensive understanding.
| Aircraft Type | Cruise Mach | Knots | MPH |
|---|---|---|---|
| Boeing 737 MAX | Mach 0.79 | 453 | 521 |
| Airbus A320neo | Mach 0.78 | 450 | 518 |
| Boeing 747-8 | Mach 0.855 | 490 | 564 |
| Boeing 787 Dreamliner | Mach 0.85 | 488 | 562 |
| Airbus A380 | Mach 0.85 | 488 | 562 |
| Embraer EMB-145 | Mach 0.78 | 450 | 518 |
| Concorde SST (Retired) | Mach 1.75 | 1,165 | 1,341 |
Decoding Airplane Speed: More Than Just MPH
Understanding airplane speed requires us to step beyond the simple miles per hour we’re accustomed to on the road. Aircraft operate within the atmosphere, a dynamic and moving environment. While ground speed—the speed of the plane relative to the ground—is what matters for flight schedules and passenger arrival times, pilots and aircraft engineers consider several different speed measurements.
Ground speed is the most intuitive speed to grasp. Imagine driving a car: your speed is simply how many miles you cover in an hour relative to the road. Similarly, ground speed is the aircraft’s speed over the earth’s surface. A tailwind increases ground speed, while a headwind reduces it.
However, from a pilot’s perspective, airspeed is crucial. Airspeed is the speed of the aircraft relative to the air it is flying through. This is the speed that determines the aerodynamic forces acting on the aircraft, particularly lift over the wings. There are different types of airspeed, with True Airspeed (TAS) being the most accurate. TAS corrects for air temperature and density variations at different altitudes and weather conditions. While aircraft instruments often display Indicated Airspeed (IAS), which is less precise and requires adjustments to derive TAS.
Read more about the nuances of True Airspeed vs Indicated Airspeed.
Measuring Speed in the Sky: Knots and Mach
In aviation, distances are measured in nautical miles (NM), distinct from the statute miles (SM) used on US highways. One nautical mile is approximately 1.15 statute miles. A speed of one nautical mile per hour is known as a knot. Therefore, aircraft speeds are commonly reported in knots, not mph, within the aviation community.
Another critical speed measurement, especially for high-speed flight, is Mach number. Mach number is the ratio of an object’s speed to the speed of sound in the surrounding medium (air). Mach 1 represents the speed of sound, which varies with altitude and temperature. Commercial jets are designed to operate below the speed of sound, in the subsonic range, typically below Mach 1.
Flying too fast, approaching or exceeding Mach 1, can lead to the formation of shockwaves along the wings. These shockwaves can drastically alter airflow, potentially causing loss of control. The Maximum Mach Number (Mmo) is a critical design limitation, representing the speed an aircraft must not exceed to maintain safe and controllable flight.
To assist pilots, especially in high-altitude jets, machmeters are incorporated into the cockpit instruments. These instruments directly display the Mach number, allowing pilots to easily monitor and ensure they remain below the Mmo without complex calculations. Therefore, when you hear about a commercial airliner cruising at altitude, it’s operating at a carefully designed and safe Mach number. Aircraft speeds may be communicated in knots or Mach, depending on the context and phase of flight.
Speed Variations During Different Flight Phases
Commercial airliners don’t maintain a constant speed throughout their journey. Various speed restrictions and flight profiles dictate speed changes during different phases of flight. For instance, there are speed limits imposed in certain airspace. Aircraft operating below 10,000 feet are generally restricted to a maximum speed of 250 knots. In the vicinity of busy airports, this speed limit can be further reduced to 200 knots or less to ensure safe air traffic management.
Beyond these restrictions, aircraft adhere to pre-determined flight profiles for each flight, optimizing for efficiency and safety during climb, cruise, and descent. Pilots set engine power and configuration according to these profiles for each phase.
Climb Speed: Reaching Altitude Efficiently
A rapid climb to a safe altitude is a priority after takeoff. Higher altitudes provide pilots with more options in case of emergencies, such as engine failure. Initially, the aircraft aims for the best rate of climb, maximizing vertical ascent in the shortest time. This involves a steeper climb angle and a relatively lower forward speed.
Once a safe altitude is reached, pilots transition to a more efficient climb profile. This involves lowering the aircraft’s nose, reducing engine power, and increasing forward speed, resulting in a shallower climb angle but faster overall progress towards cruising altitude.
Commercial airplane flying at takeoff speed
Cruise Speed: Balancing Speed and Efficiency
The cruise phase represents the majority of a long-haul flight, and speed during cruise is carefully managed for optimal fuel efficiency and flight time. Pilots set engine power based on pre-calculated flight plans, considering factors like distance, wind conditions, and fuel consumption. The resulting airspeed and Mach number determine the ground speed and ultimately the range of the aircraft.
As noted in the speed table, most airliners exhibit remarkably similar cruise performance. The laws of physics impose limitations on subsonic aircraft design. Achieving a Maximum Mach number beyond approximately 0.90-0.95 in a conventional subsonic transport becomes challenging. This limitation arises because air accelerates as it flows over the curved surfaces of the aircraft, like the wings and fuselage. Even if the aircraft’s overall speed is below Mach 1, the airflow over certain parts can approach or even briefly exceed the speed of sound, leading to increased drag and potential instability if not managed correctly.
Moreover, air density significantly decreases with altitude. While jet engines operate more efficiently in thinner air, aircraft wings require sufficient airflow to generate lift and prevent stalling. At cruise altitudes, airliners fly in a narrow speed window: fast enough to maintain lift and avoid stalling, yet slow enough to remain below their Mmo. This balancing act results in many modern airliners cruising at very similar speeds. It’s also worth noting that cruise speeds may be adjusted en route to navigate around turbulence or optimize for changing wind conditions. Learn more about flying through turbulence.
Descent Speed: Preparing for Landing
During descent, commercial planes undergo two distinct phases: cruise descent and the landing approach. Cruise descent is about gradually reducing altitude without excessive forward speed, staying well below the Mmo. This is primarily achieved by reducing engine thrust, allowing gravity to initiate the descent while maintaining a similar forward speed to cruise.
As the aircraft descends through 10,000 feet, the 250-knot speed restriction comes into effect. Pilots further reduce power and may deploy drag-inducing devices like air spoilers to decelerate. As airspeed decreases, less air flows over the wings, potentially reducing lift. To compensate, pilots deploy flaps, which are high-lift devices extending from the trailing edge of the wings, increasing both lift and drag at lower speeds. Explore the function of airplane flaps.
The landing approach phase requires significant speed reduction to prepare for touchdown. Approaches to airports are typically flown at speeds of 150 knots or less. This necessitates further deployment of wing flaps and other high-lift devices to maintain control and sufficient lift at these lower speeds.
The Realm of Supersonic Air Travel
“I feel the need… the need for speed!” – Maverick (Top Gun)
While most commercial airliners operate in the subsonic realm, the concept of supersonic commercial flight is captivating. No discussion about airliner speeds is complete without mentioning the Concorde. This iconic aircraft was the world’s only successful supersonic airliner, operating regular passenger service from 1976 to 2003 for Air France and British Airways. The Concorde offers valuable insights into the challenges and possibilities of supersonic flight and why current commercial aircraft designs are optimized for subsonic speeds.
The Concorde achieved remarkable feats, setting numerous speed records and accumulating more supersonic flight hours than any other aircraft. In 1996, a British Airways Concorde, nicknamed “Speedbird,” flew from New York to London in a record-breaking 2 hours and 52 minutes, aided by a strong 175 mph tailwind. Concordes also set records for circumnavigating the globe in both eastbound and westbound directions in 1992 and 1995. The fastest was the 1995 eastbound journey, completed in 31 hours and 27 minutes, including multiple refueling stops.
Despite its glamour and speed, only 20 Concordes were ever built, and supersonic air travel never became mainstream. The Concorde was notoriously fuel-inefficient and expensive to operate. Furthermore, the powerful sonic booms generated during supersonic flight restricted its supersonic operations to over-water routes, limiting its practicality for overland routes like New York to Los Angeles.
However, advancements in technology are rekindling interest in supersonic flight. Several startups are actively developing new supersonic transport (SST) designs, aiming to overcome the limitations of the Concorde. These modern designs leverage advanced materials, aerodynamics, and computer-aided design to minimize sonic boom impact and improve fuel efficiency. Boom Supersonic, for example, has garnered significant attention with its Overture airliner project, securing orders from major airlines like United and American Airlines. While still under development, the Overture is projected to have a cruise speed of Mach 1.7, potentially reducing flight time from London to New York to approximately 3 hours and 30 minutes.
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Jarrod Roberts
Jarrod Roberts brings extensive expertise to Thrust Flight, with over 15 years in aviation. He holds a BS in Aeronautical Science from Texas A&M Central. Jarrod’s career includes roles as a flight instructor, First Officer, and Captain at SkyWest Airlines, and he currently flies for a major legacy airline. In addition to his flying duties, Jarrod is the Chief Pilot at Thrust Flight, guiding flight instructors and shaping the training of aspiring airline pilots in the Zero Time to Airline program.
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