Airlines will be subjected to millions of dollars in fines after multiple flights were stuck on a tarmac for hours at John F. Kennedy International Airport this month. But none of the money will go toward compensating passengers who had to wait.

The fines are a result of the tarmac delay rule, which took effect in 2010 and penalizes airlines by imposing major fines if passengers are waiting on a tarmac for several hours at U.S. airports. It was designed to reduce long tarmac delays. Now, there are calls for the fines to compensate passengers, rather than go solely toward the U.S. government.

“Our suggestion is we need to have good enforcement, and at least half the fine should go to people who are actually impacted by this,” said Paul Hudson, president of a passenger airline nonprofit called Flyers Rights.

Although Congress has approved a modification to the rule, the change doesn't apply to passengers. Rather, it alters how a tarmac delay is measured.

Hudson said Flyers Rights has had meetings and exchanged letters with the Department of Transportation's Office of Aviation Enforcement and Proceedings to advocate for compensation for passengers affected by tarmac delays.

But even though the fines don't go toward compensating passengers under current rules, proponents of the rule suggest that the regulation does already benefit passengers.

For example, Hudson said the tarmac delay rule has greatly diminished cases in which passengers were held for extended periods of time.

Other consumer advocates agree. Charles Leocha, president and co-founder of Travelers United, called the rule the “poster child of what [the Department of Transportation] should do with some of their other regulations” because of its impact.

“The real bottom line is the tarmac delay rule has been one of the most effective rules that generated immediate change in aviation history,” Leocha said. “It changed everything overnight.”

Under the existing rules, tarmac delays for international flights waiting at a U.S. airport cannot last longer than four hours. A three-hour limit applies for domestic flights. Exceptions are for safety, security, and air traffic control issues. Food, water, and functioning lavatories are also requirements, in addition to medical attention if necessary.

If an airline violates the standards, that airline must pay a fine of $27,500 per passenger. That means flights could easily accrue more than $5 million in fines depending on the size of the aircraft.

The year before the regulation took effect, more than 800 flights encountered tarmac delays that lasted more than three hours. Since 2011, after a full year of the rule’s implementation, the numbers have dramatically dropped, reaching just over 100 for two of the ensuing years.

But critics of the rule argue the regulation encourages airlines to cancel flights. A report from the Department of Transportation inspector general in 2016 revealed that flight cancellations increased during the first three years after the rule was implemented. But after those three years, the following two years showed no increase in cancellations.

Airlines for America, an organization that represents airlines including American, United, and Southwest, acknowledged the concerns with cancellations, but is not inherently opposed to the regulation. The group said it is pushing for the Department of Transportation to carry out new changes to the rule as mandated by the 2016 Federal Aviation Administration reauthorization bill.

Under the rule change, the time period to measure a delay would stop once a “pilot requests the authority to return to the gate” rather than once they actually return to the gate.

Additionally, Airlines for America is also in support of exceptions in instances where exiting the aircraft could be hazardous and supports giving pilots greater autonomy.

Robert Poole, a transportation expert with the Reason Foundation, a libertarian think tank, identified several problems with the tarmac rule. For example, there may not be a gate for a plane to return to, and that crew may need to be switched out.

“It would have been far better to let each airline decide how to handle tarmac delays, with poor performers losing business,” Poole said.

The regulation attracted attention following severe delays at JFK during a snowstorm this month. Global flight tracking service Flightradar24 told the Washington Examiner that there were at least a dozen international flights that were stuck for longer than four hours. The group noted that it can be difficult to determine an exact number, because pilots often turn off transponders when parked for long periods of time.

In the meantime, Hudson claimed that the Department of Transportation has issued much lower fines in the past, and he warned that long tarmac delays occasionally “creep back” without good enforcement.

For example, Southwest Airlines was penalized $1.6 million after 16 aircraft encountered long tarmac delays in January 2014.

“In general, they give fairly low fines or no fines at all,” Hudson said. “When they do give a fine, 50 percent of it is typically waived if the airline promises to do better in the future.”

It's still uncertain whether airlines will be fined for the delays that occurred at JFK this month.

A spokesperson for the Department of Transportation said the agency is investigating the delays and is reviewing the events to determine what actions, if any, are necessary.

Leocha said a variety of factors contributed to the tarmac delays at JFK, including a lack of communication between the terminals since they are owned by different entities, but that the recent delays don’t reflect on the effectiveness of the rule.

“The lesson that we learn here isn’t that the tarmac delay rule isn’t working, it’s a lesson that that particular airport, JFK, has got real problems when it comes to communicating between terminals,” Leocha said.