House and Senate appropriators want to make sure the Air Force doesn’t hold up replacing the aging fleet of Northrop Grumman-made battlefield surveillance planes and have proposed some strict new timelines.

Lawmakers stipulate the new fleet of Joint Surveillance Target Attack Radar Systems not receive any funding for the technology maturation and risk reduction phase after March 31, 2018, according to an explanatory statement of the House and Senate Appropriations Committee’s revised fiscal 2017 defense spending bill released today.

An industry source familiar with JSTARS explained that the legislation appears to be imposing a deadline for the fleet’s radar development because some have said the Air Force is using the program also as a radar development effort and may hold up the fleet of new planes to mature the technology.

“This says the Air Force has to move forward with the program and they can’t hold up the airplanes while testing out which radar to use,” the source said. “It reiterates that this isn’t a development program. It also puts on a tight schedule to meet the operator’s needs.”

The bill approves the full $128 million the Air Force requested for JSTARS in fiscal 2017, but asserts that only $68 million is required to finish risk reduction work for the radar.

The remaining dollars should go to “other risk reduction activities and the source selection process to accelerate entry into the engineering and manufacturing development (EMD) phase of the program,” lawmakers write.

The Air Force in December released a request for proposal for the $6.9 billion JSTARS EMD phase. Lockheed Martin, Boeing and Northrop are competing for the award.