Last year, Jacqueline Thomas, a graduate student in the Department of Aeronautics and Astronautics (AeroAstro) at MIT, proposed a concept that could improve aviation without having to modify a single aircraft.
Her idea for a “delayed deceleration approach” was devised as a means to tackle two major problems facing the aviation industry: carbon emissions and noise pollution.
Tackling the challenges facing the aviation industry
As part of the final year of her time as a Ph.D. student at MIT, Jacqueline Thomas proposed her outline for a new flight procedure for pilots to follow while landing that improves noise pollution as well as carbon emissions.
Thomas made her proposal to Boeing under their ecoDemonstrator (ecoD) program. Essentially, ecoD acts as a “bench-to-bedside” innovation accelerator. It invites researchers to pitch ideas for improving aviation safety and efficiency.
By allowing for proposals to be fast-tracked into the test phase with real aircraft, ecoD allows Boeing to help students help them to solve challenges for the aviation industry and the environment.
According to a report released in October 2019 by the Environmental Protection Agency, air travel accounts for approximately 2.5 percent of global carbon dioxide emissions. What's more, it is increasing at a much faster rate than had been anticipated. On top of this, as the number of commercial flights increases, so does the number of noise complaints from citizens living on flight paths.
Changing inputs to decrease noise and emissions
“As soon as a plane is built, it’s hard to change its function. It will generate noise no matter what state it’s in,” Thomas told MIT News.
“I chose to approach the problem like an integrated system — if you can change the input, you can change the output. In other words, if you can’t change the aircraft itself (the function), you can change how it’s flown (the inputs).”
Seeing as Thomas' idea allows airlines to decrease the noise and emissions of existing aircraft without having to modify the aircraft itself, it has the extra incentive of being cost-effective for airlines.
Using her 'integrated system' approach, Thomas built a computational framework that allowed her to analyze aircraft noise and measure whether changes to the operational flight procedure would have the desired effect.
Included in Thomas' analysis were measurements of the ways in which aircraft components move and interact to generate noise, as well as flight performance data, that allowed her to gauge how the aircraft generated noise during acceleration and deceleration.
A full-scope overflight noise model
With that framework, Thomas was able to put together a full-scope overflight noise model, which could then be analyzed against community data to illustrate how tweaks to the inputs would impact noise pollution in communities surrounding airports.
“What resulted from this framework was my concept for the delayed deceleration approach, a new flight procedure where the aircraft remains cleanly configured for as long as possible during approach, meaning the flaps, slats, and landing gear remain upright for as long as possible,” Thomas explained.
“When the aircraft has a clean configuration, it is more aerodynamic, creating less drag and allowing it to maintain engines at a lower power setting for longer duration in the flight. As a result, the plane burns less fuel, decreasing carbon emissions, and generates less noise for the community on the ground.”
Testing the procedure with real aircraft
Through the ecoD program, Thomas handed her procedure over to Boeing engineers in Seattle, Washington, who communicated it to the crew of a test flight in real-time through a chat feed that Thomas and her supervisor R. John Hansman, professor of aeronautics and director of the MIT International Center for Air Transportation, could see on a computer, alongside the plane's location.
Immediately after the landing, the plane's flight crew joined Thomas, Hansman, and the group of Boeing engineers for a debrief.
“The pilots reported they felt very comfortable with the procedure, and didn’t experience any flyability issues," Thomas said. "When the models say that it works and has all of these benefits, and the pilots say ‘yes, we can fly this,’ and a commercial plane actually flies the procedure and matches the predictions from the models, then it really shows that we can do this, and we should because it’s a win-win for everyone."
If her doctoral thesis, based on her “delayed deceleration approach” concept is anything to go by, Jacqueline Thomas very likely has a bright future in store as an engineer. Quite impressively, Thomas successfully defended her thesis remotely via a Zoom call due to coronavirus restrictions — an experience she described as "bizarre".
“My goal for the future is to make this a standard flight procedure," the MIT student explained. "[This] means I need to keep working on refining this process so we can scale it up in a way that makes sense to implement in real airlines operating today.”