It's no secret that parking tickets generate revenue for the city. But does the Nutter administration actually want drivers to rack up fines?

"That couldn't be further from the truth," said Andrew Stober, chief of staff for the mayor's Office of Transportation and Utilities.

Stober yesterday sought to clear up any misconceptions one day after he publicly expressed concern about a proposed pay-by-phone parking app that could result in fewer tickets and perhaps less money for the city's cash-strapped school district.

The mobile app, proposed by the Philadelphia Parking Authority, would enable drivers to use their phones to pay for curbside parking. App users would receive a text-message alert when their time is about to expire and would be able to avoid a ticket by adding time remotely.

"We are not in any way saying that less ticket revenue is a bad thing," Stober said. "We're saying that we should just understand what the implications of that are so . . . it doesn't come as a surprise to anybody."

Stober said the city supports a bill that would create a pay-by-phone app.

"What we said [Monday] was that a mobile parking application is long overdue in Philadelphia," Stober said. "It's a great benefit to customers. It helps people avoid tickets, and in fact, the PPA, we think, is showing really great leadership here in setting up a policy that will ensure that turnover of parking spaces continues."

Under the proposed plan, drivers who use the app would pay a higher rate if they add more time via their phone - a disincentive to hog a parking space for hours on end.

Yesterday, Vince Fenerty, the Parking Authority's executive director, said he was shocked to hear city officials express any reservations about an app.

"I believe they are apprehensive about this program because people could get less tickets and revenue could drop, just like it could rain tomorrow," Fenerty said. "Do we want people to come in and have a good experience in Philadelphia and have many options to pay for their parking, or do we want to limit payment opportunities so eventually some of them will get tickets because they won't make it back in time to their meter? I don't think that's being business-friendly or tourist-friendly."

Fenerty's criticism stemmed from Stober's testimony Monday before City Council members who sit on the Committee on Streets and Services, which took public comment on the Parking Authority's pay-by-phone proposal. (The committee voted to advance the bill to the full Council.)

During the committee hearing, Stober called for an analysis of the potential financial impact on the school district if an app is launched.

Last year, according to Stober, the school district received about $9.7 million from the Parking Authority. Fenerty said the 2014 total was closer to $11 million, with ticket revenue "as a primary source."

Fenerty said he agreed to provide the city with a "small analysis." He said he believes the app would be "revenue-neutral" and hopes to have it in place by late summer or early fall.

On Twitter: @wendyruderman