In the wake of our single-pilot operations discussion in June, this month we’re taking a quick look at another operational future: supersonic flight. Or, as Doc Brown would say, “Back, to the future!”
That was of course a nod to the Michael J. Fox movie from 1985, but actually speaks to the airline industry’s initial design success (though a commercial failure) of supersonic flight with the joint British Aircraft Corporation’s (later BAE) and France’s Sud Aviation (later Airbus) 1976 rollout of the Concorde. At the same time, the Russians (formerly known as the Soviets) were trying out the supersonic thing as well and actually introduced the Tupolev Tu-144 two months prior to the Concorde’s unveiling. Even though it hit the skies at Mach 2, the Tu-144 had significant reliability issues and was quickly removed from passenger service. In the U.S., Boeing also dabbled with a supersonic airliner (B2707), but abandoned that to build the 737 instead—which is too bad.
Anyway (and without making this a history of the Concorde), the short story is that SST (supersonic transport) has always had a fundamental inconvenience—the associated “boom.” A build-up of pressure waves compressed until they merge into a single shock wave at around 741 mph (at sea level), leading eventually to the release of the compacted sound waves in the form of a thunderclap. Because of the associated noise, which is generated as long as the aircraft remains in supersonic flight, an uncomfortable carpeting effect of noise pollution and potential damage to some structures (i.e., windows), continuously occurs along the aircraft’s flightpath. For the Concorde, this resultant disturbance meant that it could fly supersonic during open ocean portions of its trips, and everything else was at regular old jetliner speeds around 400 or 500 mph. The consequence was chronic inefficiency and no good reason for operators to order the relatively small, expensive jet—nor for passengers to pay the 2025 equivalent of $20k per flight. So, instead of building the 300 that were planned during the proof-of-concept period in the 1960s, only 20 were ever constructed. This has of course left a bad taste in manufacturers’ mouths for decades now. But as mentioned in last month’s article, where this industry has only ever removed pilot stations from the flight deck, this industry has also never gone slower—only faster over time. We are arriving at the dawn of a new SST era.
Pop quiz: If an aircraft is flying faster than the speed of sound, how are the pilots of that supersonic aircraft able to communicate with air traffic control and other aircraft?
Answer: Radio waves are a form of electromagnetic radiation, which means they travel at the speed of light, or about 671,000,000 mph – which is a tad faster than the speed of sound.
So where do these fun facts and historical aviation footnotes leave us?
Leaning on military stealth technology as well as NASA research and modeling including the X-59, companies such as Boom Supersonic, Spike Aerospace, Exosonic, and Virgin Supersonic are all in the race to develop and deliver quieter, more efficient SST airliners. With lighter, yet stronger composite materials coupled with improved aerodynamic design, the ability to delay the onset of compressibility and relieve it more effectively means a significantly lower sound signature making flight in the supersonic range not only palatable, but highly desirable for those interested in getting to their destinations more quickly—and who isn’t? In fact, Boom recently had their own proof of concept when they (literally) quietly broke the sound barrier in January, doing so in the same airspace previously occupied by Chuck Yeager in 1947.
Further, Boom is planning to have their Overture jet enter service by 2029, and at its current design speed of Mach 1.7, means getting to destinations twice as fast as current transport category aircraft. Even airlines are starting to bet on this technology coming to fruition with United and American having placed orders for 15 and 20 Overture jets along with 35 and 40 options, respectively. Japan Airlines also ordered 20, and a mystery European operator submitted an option for 15 of the Boom jets.
Assuming at some point in the likely near future, SST will be re-introduced to the industry, there will be a host of required supporting actions and measures to go along with it. New regulations and procedures will need to be created by regulators, operational arrangements instituted and approved between ICAO states, ATC systems and procedures evaluated and amended in order to facilitate supersonic flight, ground operations and infrastructure readied (especially if mid-Pacific flights will require a fueling stop before reaching the planned destination), and pilots trained to manage the unique aspects of flying faster than the speed of sound.
“Roads? Where we’re going, we don’t need roads…”
Before we close for the month though, here’s a thought brought to mind by last month’s single-pilot ops article: Boom’s Overture jet is currently designed for two pilots, which is good. However, its speed is such that instead of needing to augment a flight with one additional pilot as is currently required, for example, on a 7+ hour flight from Newark to London, it could be completed in about 3.5-hours with just two pilots. San Francisco to Tokyo with a double augmented crew now, would be 6-hours instead of 12 hours and could again, be flown with only two pilots. Some of these flights could become “turns” in airline parlance, where a two-pilot crew flies to the destination and back in a single day—or simply lays over and returns the next day. Even in domestic airspace this potentially means more legs flown per day by a single pair of pilots, resulting in fewer required pilots overall in order to complete the same amount of scheduled flying, increasing airline operational as well as financial efficiency. This is just something to think about.
