Sometime next year Mike Sinnett, Boeing’s vice-president of product development, will enter a small, experimental aircraft and – he hopes – do nothing.

Boeing Commercial Airplanes (BCA) has started exploring autonomous flight technology for passenger-carrying aircraft and Sinnett, as a pilot and engineer, plans to fly in – as opposed to “fly” – the first test subject. Boeing’s newly developed, machine-learning software is already loaded into a flight simulator, which Sinnett and his team have been using to refine the algorithms. But the real test will come next year when flights begin with Sinnett on board, as the software makes decisions that respond to changes in the environment.

“I’m not ready to talk yet about what those decisions are,” Sinnett says, speaking to journalists earlier this summer. “And I’m not going to close the loop on the airplane. But I’m going to make sure the decision is made with the same set of inputs that pilots use to make decisions and I’ll record the decision that the airplane makes.”

Boeing has not publicly identified the aircraft Sinnett will use next year, except to describe it as a small and far less complex than a commercial transport. But the size and complexity of the test aircraft will escalate several levels in 2019, as Boeing reintroduces a 787 into the ecoDemonstrator fleet. Taking incremental steps towards greater autonomy, the ecoDemonstrator 787 will incorporate software to manage taxi and take-off in place of a pilot, Sinnett says.

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The ecoDemonstrator is tasked with evaluating technologies that could be used on future or existing Boeing aircraft. By studying new autonomous control modes on the 787 ecoDemonstrator in 2019, Boeing could have the technology ready to appear on its next clean-sheet aircraft. Boeing has proposed developing a family of new aircraft after 2024 to fill a perceived gap between the 737 Max 10 and the 787-8.

It’s an extraordinary move within BCA. Although sister businesses in the defence and space markets are deeply experienced with autonomous vehicle control, BCA’s approach to cockpit architecture for passenger-carry transports emphasises that a human pilot has ultimate control. Even in an age with flight envelope protections enabled by fly-by-wire controls and auto-landing systems, the pilots of 777s and 787s are never “out of the loop”.

Sinnett acknowledges the cultural shift, then points out that BCA is not yet committed to developing an autonomous airliner. “We're not going there yet. We're exploring,” he says.

Indeed, there are few signs the commercial transport market is prepared for such a disruptive shift. As a whole, the industry is more profitable than ever and all projections point to continued traffic growth for the foreseeable future. But that very traffic growth sets the industry up for a tough challenge: where are all the pilots going to come from? To meet projected demand for new aircraft, Boeing estimates that airlines will need to hire two million workers over the next 20 years, including 637,000 pilots. An ever-shrinking pool of military-trained pilots means airlines could struggle to find enough classic “aviators” with a rich depth of aviation knowledge and expertise.

Twenty years from now, Sinnett wonders, are pilots going to be operators of machines rather than aviators? “That drives you to think of things differently,” he says. “The pilot is ultimate authority of a commercial aircraft today, but that’s an experienced pilot with the right level of proficiency and the right level of aeronautical knowledge. If the assumption that all of those pilots will always be available is shown to be an invalid assumption 10 years from now or 20 years from now, then we have to have a different plan.”

Boeing is not the only company contemplating the possibility of passenger-carrying aircraft with fewer or no flightcrew within 20 years.

The research arm ofSwissbank UBS published a report on 7 August that notes it would be feasible to operate “remotely controlled airplanes carrying passengers and cargo” by about 2025, potentially saving the world’s airlines USD 26 billion a year in foregone pilot salaries, reduced fuel bills and lower training costs. Although bank’s researchers elaborated on the financial benefits of a shift to pilotless aircraft, they recognised that the industry was unlikely to be ready within eight years to employ such technology. And, even if the industry can overcome regulatory barriers, airlines can expect to find that the population is mostly unwilling to fly in a pilotless aircraft.

Still, if it can be achieved, an automated cockpit solves two of the industry’s most intractable problems at the same time: a pilot shortage and creeping labour costs.

The regulatory barriers, however, are significant. For this reason, the industry seldom transitions to the full employment of a new technology in one great leap. There are usually smaller steps. A common example is the transition to carbonfibre-based structures instead of metal. The first applications appeared in the 1970s on secondary structures, such as the rudder for the Airbus A310. By the early 1990s, Boeing was ready to replace metal with carbonfibre on the empennage of the 777. More than 15 years later, the 787 entered service with a carbonfibre fuselage and wing – nearly 40 years after the first application.

Some would argue the transition to an automated cockpit also started about 40 years ago. That was when US and European regulators accepted a two-person cockpit, which removed a requirement for a navigator. Since then, the industry has introduced new autopilot features, including autoland, which allows the aircraft to navigate final approach and landing by itself in certain situations at qualified airports.

Sinnett offers a possible roadmap for a step-by-step, incremental transition from the crewed cockpit of today to a fully pilotless aircraft. He notes that some airlines that operate a 777 on a 16h mission require five pilots on board: a captain, a first officer, a two-person reserve crew and one pilot dedicated to the cruise stage of the flight. By introducing more automated redundancy in the cockpit, the five-pilot crew might be the first thing to go.

“Some of the first steps might be to go from five [pilots] to four, and then from four to two to reduce the number of augmented crewmembers on the flight. That may be the first step along the way,” Sinnett says.

“Another step may be to go from two pilots during cruise to one pilot during cruise and [another] pilot on board the airplane, but maybe getting meaningful rest. It could be that you have a one-pilot operation.”

Single-pilot cockpits are banned for most types of commercial operations today, but there are exceptions. Sinnett notes that the US Federal Aviation Administration allows certain airlines to fly up to 10 passengers with a single crew member. One example is US regional carrierCape Air, which operates nine-seat Cessna 402s with a single pilot.

“We as a society are willing to accept the risk – given the size of the airplane, the number of people on board and the weight of the airplane – that it can be operated by a single pilot,” Sinnett says. “As a society you can ask the question: if it’s okay for a single pilot to fly 10 passengers in a certain airplane type, why would it not be okay for a single pilot to fly a freighter with no passengers on board, and right now that is not allowed. That is also potentially one of the steps along the way.”

Of course, the step beyond single-pilot is no pilot. As Boeing considers the path for introducing higher levels of automation, the company still is not sure whether this should be the last step or the first. In the latter example, the industry would bypass the step-by-step process and leap as quickly as possible to a pilotless cockpit.

“What isn’t clear yet to anyone in the industry – ourselves included – is whether it’s a single step from what we have today to full autonomy, or whether it happens in step-wise improvements over time – each of which retains the same level of safety integrity that we have today. We don’t know the answer to that question,” Sinnett says.

“You can imagine if you took those successive steps it might take a lot longer to go from where we are today to all the way. You can imagine six steps to autonomy – each of which would be very, very difficult, each of which would be a battle in its own right. So maybe taking each step isn’t the right answer, and that’s part of what we’re trying to figure out.”

The critical challenge is meeting the industry’s standards for safety. Driverless cars are quickly becoming a reality, but the US automotive industry faces a different bar for safety. In 2016, for example, more than 40,000 Americans died on roads, but none died on airlines in US airspace.

“So that drives a very different way of thinking about the problem,” Sinnett says. “We have to have the same level of integrity that we have today.”

Aircraft already possess multiple automated functions, which Sinnett lists: autopilot, autoland, autothrust management, auto-navigation, aircraft health monitoring and reporting. These systems are automatic but not autonomous. At least two pilots are on board and assigned to monitor each function and intervene if anything goes wrong.

For example, the autopilot fails in very rare cases, Sinnett says. Suppose the crew has programmed the autopilot to make a turn, but then it doesn’t and the aircraft continues flying in a straight line. The pilots are on board to recognise such problems, he says. They would disconnect the autopilot, make the turn manually, then reconnect the autopilot while making a note to report the incident.

Such a scenario involves a functional failure but not a safety issue, Sinnett says, since a human intervened to solve the problem The system is designed to be extremely safe, with any quirks managed with human monitoring and intervention. In a fully autonomous aircraft, the systems would have to be reliable enough to manage themselves.

“Without the pilot in the loop to catch that first link, it begs the question, what would the next thing be that happens? Would the airplane go five miles off course?” Sinnett asks. “Some of the work we’re doing today is to try to figure out where all those gaps are in the design of an airplane and how you would close those gaps successively through a series of steps that go from where we are today to full autonomous operation.”

Boeing may also have to persuade regulators not only to accept autonomous systems, but to change the way they verify that software is safe today. The most advanced software in aircraft today is certificated as airworthy using a prescriptive series of tests. To be certificated, software code is given a set of inputs and it must generate the same set of outputs without variation. A fully autonomous system, however, uses machine learning software, which reacts differently to situations as flight conditions changes – sometimes in ways that are impossible to anticipate.

“Nobody is smart enough to program all the potential things that can happen in the operation of the airplane and then demonstrate the airplane does the right thing all the time. So we have to come up with a different way to do it,” Sinnett says.