An app that would allow Philadelphia drivers to pay for parking by phone - and add time remotely to avoid a ticket - could be launched as soon as fall, if the Parking Authority gets the green light from City Hall.

But the Nutter administration fears the app will hurt the School District, which benefits from parking ticket revenue.

"This is innovation," Vince Fenerty, executive director of the Parking Authority (PPA), said Monday in response to the administration's concerns. "It's about making it easier to pay your meter."

Pay-by-phone apps have been launched in cities across the country, including Phoenix, Washington, and Miami.

In Philadelphia, the app would be run by an outside company. It would let users to pay through their smartphones and receive text-message warnings when their time was running out.

Richard Dickson, the PPA's deputy director, said users could add more time at the initial rate, up to the posted time limit. To stay longer, users would pay at higher rates - for example, $2 for the first two hours, $4 for the second two hours, and $6 for the third two.

To assure turnover of parking spaces - a stated PPA goal - there would be upper limits, such as six hours in a two-hour zone, Dickson said.

Andrew Stober, chief of staff for the mayor's Office of Transportation and Utilities, said a mobile parking-payment system is overdue. But he asked the PPA to provide a more detailed analysis of how it would affect the School District. Last year the district received $9.7 million from the Parking Authority, money drawn from tickets, meter fees and parking permits, among other areas.

"At a time when we are struggling to make sure the schools have the resources that we need, we need to make sure that we're not digging ourselves deeper in a hole," Stober said.

Fenerty called that concern "preposterous."

"We give tickets because we want people to comply with parking regulations," he said. "Tickets are not there as a punitive measure. They're getting people to obey the parking ordinances, and that's what we're doing."

Fenerty estimated the app would be revenue-neutral, because some users would pay a higher rate to stay in parking spaces past the posted limit. And he said the app would help city businesses by making it easier for shoppers to pay for parking.

A committee of Council on Monday approved the bill, which will now go before the full Council for a vote. Mark McDonald, Nutter's spokesman, declined to comment on whether the mayor would sign the bill into law.

PPA officials say they hope to award a contract for the app by the end of May. Dickson said it would then be launched in Center City within 90 days, and in the rest of the city 90 days after that.