By most accounts, the JFK AirTrain has been a success story. After a fatal incident cast a pall on the project a few months before the planned opening, the AirTrain saw 2.5 million riders in its first year of operations and 6.5 million riders in 2014, its tenth year of operations. Even as Gov. Andrew Cuomo pushes to build a misguided LaGuardia AirTrain via Flushing, the AirTrain has been an improvement for access to JFK airport.

Early last year, when making a push for support for his LaGuardia plan, Cuomo touted the benefits of the JFK AirTrain. “AirTrain JFK has proven to be not only one of the most convenient and affordable ways of getting to and from the airport, but also one of the most popular,” he said, noting an eight percent increase in paid ridership between 2013 and 2014 alone. Over 10 million riders use the AirTrain to ride between terminals and nearby garages for free.

But a funny thing happened on the way to 6.5 million riders: The Port Authority has quietly reduced the frequency of service on the AirTrain. A few days ago, a Twitter user reported that the Port Authority was promoting 14-minute headways between AirTrains shortly before noon on a weekday. For a zero-person automated system with ample rolling stock to run trains at five-minute headways, this seemed exceptionally egregious, and a few folks went digging.

Eventually, Chris O’Leary dug up some historical data. As recently as 2009, the Port Authority operated the JFK AirTrain on five-minute peak-hour headways and 10-minute off-peak headways. A recent brochure tells a much different story as peak headways are now 7-12 minutes with service operating every 10-15 minutes between 7:30 a.m. – 3 p.m. and every 15-20 minutes from 8 p.m. until 4 a.m. This is, effectively, a 50 percent service cut. Take a look:

It’s not quite clear when these new timetables went into effect or why. The Port Authority hasn’t responded to requests for comment yet. But posts on an aviation-related message board indicate reduced AirTrain frequency as long ago as 2011. This isn’t a new problem, but it seems to be one the Port Authority has slipped past the public without much notice.

Despite silence from the Port Authority on this issue, it’s my understanding that this reduced service is a result of the age of the system and the need for repairs. With cars in the shop and the system’s constantly undergoing maintenance, the Port Authority cannot maintain the headways it used to run seven years ago. For a 12-year-old system, this seems problematic and worse still is the lack of transparency regarding operations. There’s no real need for the Port Authority to keep these issues under wraps, and if the state is about to sink a few hundred million dollars of public funds into another airport rail system, we should know that operations can keep pace with ridership.

Right now, the JFK AirTrain remains popular even as service is cut. But trains are more crowded, and travelers have to leave extra time to account for long AirTrain waits. That the PA doesn’t appear to view this reduced service as a problem is cause for concern. But that’s just another day in the fun world of the Port Authority.