WASHINGTON — If the U.S. Air Force moves forward on a proposed initiative to buy light-attack planes, it won’t happen by the end of 2018.

The service intended to put out a final request for proposals this month for a potential light-attack aircraft program, but the date has now slipped into 2019, an Air Force official confirmed Tuesday.

“The Air Force does not anticipate release of the final Light Attack Request for Proposal by the end of the calendar year as we complete additional analysis,” Air Force spokeswoman Capt. Hope Cronin said in an emailed response to Defense News.

The service released a draft solicitation on Aug. 3, following two experimentation campaigns that brought the Sierra Nevada Corp.-Embraer A-29 Super Tucano, Textron’s Scorpion jet and AT-6 attack plane, and L3’s AT-802L Longsword to Holloman Air Force Base in New Mexico for several rounds of test flights.

The second set of flight experiments between the A-29 and AT-6 were curtailed this summer after an A-29 crashed, killing its pilot. However, the Air Force maintained that it could garner the data it needed on aircraft maintenance and network operations while testing the planes on the ground.

Air Force acquisition officials have shied away from declaring whether a program of record will begin in the fiscal 2020 budget, but the August presolicitation seems to limit the contenders to the A-29 and AT-6, stating that SNC and Textron “are the only firms that appear to possess the capability necessary to meet the requirement within the Air Force’s time frame without causing an unacceptable delay in meeting the needs of the warfighter.”

The goal of the light-attack experiments is to prove whether the Air Force can quickly bring industry to the table to experiment with off the shelf equipment and rapidly make a decision about whether to buy it.

In that light, the delay in releasing the final request for proposals is at least a slight setback, as it’s unclear whether the wait for a final RFP could also push back the Air Force’s proposed due date for awarding a contract — before the start of the 2020 fiscal year on Oct. 1.

But it remains unclear whether the Air Force will have the money to buy it. Officials have maintained that a light-attack capability is “additive," meaning that they would not be willing to sacrifice procurement dollars designated for aircraft in existing or planned programs of record so that it could buy the AT-6 or A-29.

However, the Pentagon’s top-line budget is still uncertain. Defense Department budget officials had geared up for a $733 billion budget in FY20, only to have President Donald Trump call for a cut to $700 billion. Now, it appears that number is growing after intervention from Defense Secretary Jim Mattis and congressional hawks, and could be as high as $750 billion.

Whether the light-attack aircraft program fits into any of those top-line budgets is currently unknown.