Chicagoans have sent nearly two tons of clothing, medicine, food, and water to Pakistan in the last week, and there’s a lot more to send. But Pakistan International Airlines is struggling to keep up with the good intentions.

PIA is carrying all relief donations to Pakistan for free in the cargo compartments of its passenger flights. But those flights only leave from Chicago twice a week. Meanwhile, the donations that people want to send on them keep mounting.

“People, they are waiting to deliver the cargo, and we don’t have right now the space,” says Sajid Siddiqui, passenger sales manager at PIA. Siddiqui says part of the problem is that PIA doesn’t have its own warehouse in Chicago to hold donations until they’re sent. Instead, the airline rents space from a cargo-managing company at O’Hare. Siddiqui says he’s looking into ways to find more.

PIA’s third flight with relief goods from Chicago leaves today.