One US airline is keeping middle seats open. Here's what science says about it.

Delta Air Lines is the only major U.S. airline that continues to block airplane middle seats in an effort to limit the spread of COVID-19 on its flights. The airline has committed to continue to do so through the end of April. Is this good public health practice or bad business practice?

Conventional wisdom suggests that this is a good idea for passengers, giving everyone a sense of health security and that the airline is interested in their well-being, by keeping passengers as far apart as possible within the confines of an airplane cabin. However, conventional wisdom is not always correct, as our recent research points out.

From a public relations perspective, blocking middle seats is a highly visible action that Delta can take to demonstrate its commitment to passenger safety. Other actions, like deep sanitizing airplanes and mandatory face coverings (now a federal requirement) all serve to protect passengers and flight crew.

The business case

From a business standpoint, Delta is losing little in blocking middle seats. Airline capacity in recent weeks has been down 40% compared with pre-pandemic travel, though the recent uptick may indicate a new upward trend.

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However, blocking middle seats on a 3-3 airplane seat configuration reduces each airplanes capacity by 33%. On a 2-3 airplane seat configuration, available seats are reduced by 40%. Therefore, the impact on Delta’s financial bottom line has been minimal, with much of it recouped by more passengers opting to fly with them rather than their competitors.

The key issue is whether blocking middle seats makes flights safer for passengers.

Safety first

Airplane air filtrations systems are comparable to air circulation systems used in hospitals. This means that filtrated air circulates into airplane cabins every two to three minutes. Passengers can take advantage of such systems by keeping their individual air vents fully open to keep a steady flow of filtrated air around them during their flight.

The crux of the middle-seat debate depends on how the virus is transmitted in an airplane cabin. Conventional wisdom suggests that virus transmission occurs horizontally (between passengers in adjacent seats in the same row, labelled east-west transmission).

However, virus transmission could also occur between passengers in adjacent rows, labelled north-south transmission. Keeping middle seats blocked is reasonable if there is only east-west transmission. With north-south transmission, the overall risk to passengers on an airplane might be lower with middle seats filled and adjacent rows blocked.

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Every type of airplane in an airline’s fleet has its own unique seat configuration. With mandatory face coverings and high-performance air filtration systems, blocking middle seats may provide limited if any additional health benefits to airplane passengers.

Given that the nation is moving closer to herd immunity, with more than 2 million vaccines administered every day, Delta would be wise to relax its blocked middle-seat policy and use sensible seating rules based on the number of seats on an airplane and the number of passengers booked on the airplane.

As we approach the summer travel season, airlines are likely to see a bump up in demand, resulting in more planes filled at or near capacity. Seeing a daily passenger count of 2 million within the next several weeks is well within reach. Mandatory face coverings will continue to be a part of air travel, but blocking middle seats makes little public health or economic sense, even if conventional wisdom suggests otherwise.

Sheldon H. Jacobson, Ph.D., is a founder professor of computer science at the University of Illinois at Urbana-Champaign. He applies his expertise in data-driven risk-based assessment to evaluate and inform public policy and public health. This column was originally published in the IndyStar.

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This article originally appeared on Indianapolis Star: Airline open middle seats to prevent COVID. What science says about it