Editor's Note: This article was first published in Forbes. For Oliver Wyman's ongoing strategic advice and expertise on what healthcare industry stakeholders should do in response to the rapidly evolving novel coronavirus (COVID-19) pandemic, see our ongoing series.

After the terrorist attacks on September 11, 2001, it took the nation’s aviation industry about a decade to fully recover. There were two recessions in the following 10 years that didn’t help, but one of the persistent problems was that Americans were nervous about traveling, despite the low odds of being involved in a terrorist attack.

The immediate impact on aviation from COVID-19 dwarfs the aftermath of 9/11, with a drop in demand in excess of 95 percent versus around 30 percent in the months following the attacks. Nevertheless, it poses a similar challenge: What will it take to get people to feel safe and flying again?

As the United States finally begins to consider reviving the economy after months of stay-at-home orders, social distancing, and alarming death statistics, one of the biggest tasks ahead will be rebuilding public confidence. This job will be made even more difficult by the almost certain need to continue practices like social distancing and wearing protective gear well after businesses reopen.

A COVID-19 vaccine would work to allay fears, but one is not likely to be ready before the second half of 2021 at the earliest. Until then, would-be passengers need to know that airlines are fully informed on COVID-19 developments and playing by the same set of safety rules, just the way they did when it came to terrorism post 9/11.

Why Aviation Matters

Rebuilding customer trust — and a return to a semblance of business as usual — is especially important for global aviation, an industry that sustained among the steepest declines in demand because of the coronavirus. As of April 22, about 76 percent of US airline capacity had been taken out of service, data from Oliver Wyman’s PlaneStats.com show, and more aircraft are expected to be parked in May. US domestic flights are averaging 10 passengers per flight, according to the trade group Airlines for America; net bookings are down 99.5 percent year over year, and booked revenue is 103 percent lower. 

Making the public feel safe is also important for the broader economy. When people are ready to think about traveling again, they will probably also have the confidence to go shopping in a store or dine in a restaurant. A revival in air travel, most likely accompanied by a return of business travel, tourism, and hotel stays, would mean the economy is coming back.

To succeed, what’s needed is a well-coordinated effort to convince the flying public that airlines are staying ahead of the virus and protecting them. Travelers need a system in place that spells out how serious the threat is on any given day and what airlines are doing to mitigate it.

After 9/11, the symbol of that coordination and intense monitoring came in the form of a color-coded threat level assessment that informed the traveling public about the degree of risk. In March 2002, the Homeland Security Advisory System was implemented with five threat levels designated by a color to describe the existing risk. The lowest risk was indicated in green; the highest in red. Despite criticism that it made people feel more nervous than safe, the system was used for almost a decade.

Threat Assessment for Disease

What we need the government and industry to do now is create something similar for infectious disease outbreaks like COVID-19. But unlike the terrorism alerts, this system would need to be much more transparent about the data determining the risk and much more specific about the safety procedures that would accompany each level.

The post 9/11 measurement failed to offer specifics because most of the information used to determine the threat was classified. That should not be the case when it comes to public health data where transparency is paramount when containing the spread of disease. Where terrorism is a constant, underlying threat that requires procedures put in place in perpetuity, outbreaks of infectious diseases are unpredictable, based on a variety of factors beyond human control. Safety procedures may need to be frequently tweaked to reflect the level of risk and changing conditions.

We propose a five-level, color-coded infectious disease threat assessment that would spell out conditions that correlate to each color and procedures travelers could expect every airline and airport to follow. For instance, COVID-19 would currently fall into the severe assessment category, based on such conditions as the declaration of a national state of emergency, widespread shelter-in-place orders, and an uncontrolled spread of the disease. Travelers could expect airlines to provide personal protective gear for all passengers and employees, intermittent hand sanitation during flights, surface disinfection during flights, and no in-flight service, among other things.

For more information on why trust and data transparency are critical during a pandemic, and always, and how an infectious disease assessment scale like the one below can reinstate our trust in travel safety, read the full Forbes article here.

Educating the Public

Singapore has created a similar system called the Disease Outbreak Response System Condition, or DORSCON, which has only four color-coded categories. It was used during the 2003 SARS epidemic and the 2009 H1N1 pandemic as well as Singapore’s current battle with COVID-19. 

An infectious disease threat assessment would help educate customers about how to fly during certain conditions and what to expect when arriving at airports or boarding planes. For terrorism, we all now know to pack only liquids limited to travel-sized containers of 3.4 ounces or less and be ready to take off our shoes for Transportation Security Administration screeners. With the infectious disease threat assessment, people would know that a fever or bad cough is likely to keep them off a plane when the level is orange or higher and that onboard passengers may be required to wear a mask.

Taking passenger temperatures before flights or submitting test results for viral antibodies may also eventually be necessary. In the end, coming up with an agreed-upon set of rules that all airlines will follow will make it easier to enforce and help passengers become comfortable when they see them in practice. These common rules might also facilitate international travel by providing governments a common set of control measures.

More Outbreaks to Come

COVID-19 was not the first outbreak curtailing air travel — examples include SARS in 2003, H1N1 in 2009, and Ebola in 2014. Nor will it be the last. As the world becomes more interconnected, we will continue to experience the rapid spread of disease on a global scale.

Despite lockdowns in China and other parts of Asia, US airlines were caught off-guard by the speed and spread of this pandemic in the US, in part because of conflicting official information and messages. The industry needs to avoid politicization of passenger safety concerns and focus instead on industry coordination both domestically and internationally.

Over the long run, having an established threat assessment protocol, based on scientific data, may provide a solution should we ever have to face down another pandemic. In the short-term, this system could provide the kind of concrete evidence the flying public needs to know that it’s safe to fly again.

Anna Ramundo, an engagement manager in Oliver Wyman’s Transportation and Services practice, contributed research and insights to this article.