Without more money from Congress, the Marine Corps will have to stop flying aircraft this summer, the head of Marine aviation said on Wednesday.

“If I don’t get more money, I’ll stop flying in July or August,” said Lt. Gen. Jon Davis, deputy commandant for aviation.

For now, Marine pilots are flying more hours than Congress has funded with a temporary budget deal and Marine Corps leaders hope lawmakers will provide more money before the end of the fiscal year in September, Davis said.

“We’re 8 percent shy of what we need to fly for our flight hours,” Davis said Wednesday at a Defense Writers Group breakfast. “We’re flying to our plan right now. So I would say we’re running hot on our budget for our flight hour goals.”

If lawmakers pass another temporary spending measure for the entire fiscal year 2017, which would leave funding flat at 2016 levels, the Marine Corps will run out of money for flight hours, Davis said. However, he also assumes “the country has got more sense than that,” he said.

“I’m highly confident that no one will ask the Marine Corps to stop flying,” Davis said.

But without more money for flight hours, senior Marine commanders would have to decide which squadrons could continue flying, he said.

“If we had to do it, we’d propose that the operational forward deployers would keep flying and the guys in the back of the bench wouldn’t,” Davis said.

However, having non-deployed Marine squadrons stop flying would further exacerbate the service’s aviation woes, Davis said. The Marine Corps has not met its goal for flight hours since 2012, and that means Marine pilots today are not trained to the level they need to be, he said.

“They’re flying safe airplanes; they personally are safe; but their proficiency and experience at dealing with things that go wrong is not where it needs to be,” Davis said.

Crashes of Marine aircraft increased toward the end of 2016, and ongoing reviews show there was “nothing wrong with those airplanes,” he said.

“We’re not seeing a materiel failure component to those aviation mishaps,” Davis said. “It’s mainly human error.”

In one incident, a “perfectly serviceable” AV-8B Harrier went into a spin and crashed in September off Okinawa while taking part in a training exercise, he said.

“That bothers me because I grew up flying Harriers,” Davis said. “We don’t know why it went into a spin. The airplane is supposed to be very spin-resistant. I’ve never spun a Harrier and I’ve got 3,300 hours or something flying a Harrier.”

The plane was flying with extra fuel tanks, so Davis has ordered that Harriers not carry such tanks during air combat training in case it was a factor in the crash, he said.

The antidote for human error is having pilots fly more while enforcing standards and “doing things by the book,” Davis said. But the Marine Corps faces an ongoing lack of spare parts that keeps many aircraft on the ground, he said.

“The No. 1 thing that we can do to help improve readiness on the flightline for the Marine Corps is to fix our spare parts problem,” Davis said. “Across the Department of the Navy, we do not have the spare parts we need — it’s not just the Marine Corps; it’s the Navy as well — to sustain our airplanes and maintain our readiness goals.”