Two senior Pentagon officials this week offered House lawmakers differing views on how the Air Force should shape its KC-135 aerial tanker replacement fleet, as the service moves closer to formally launching the multibillion-dollar effort.

Air Mobility Command vice chief Lt. Gen. Christopher Kelly told the House Armed Services force projection subcommittee Feb. 28 that he would prefer the Air Force replace its aging KC-135s with some mix of medium- and large-sized aerial tankers. Deputy service Chief of Staff for Acquisition Lt. Gen. Donald Hoffman, meanwhile, told the panel he advocates buying only a single version of a medium-sized refueling aircraft.

Military officials and defense analysts this week agreed the service appears to have convinced the Office of the Secretary of Defense and most lawmakers to support the potentially $200 billion program. The biggest unresolved question, they said, is what size taker -- medium or large -- the service should buy or whether a combination buy would be best.

A recently completed analysis of alternatives completed by RAND examined both medium and large tankers, according to Michael Kennedy, associate director of the think tank's Project Air Force. He also testified at the hearing. Kelly told the subcommittee, however, that the AOA stopped short of endorsing one particular aircraft that could be entered into the competition.

“Which one is best depends on specifics of mission mix and other issues and it literally -- all the analysis we did shows them to be approximately equally cost effective,” Kennedy said. The RAND analyst did, however, offer his “personal opinion” of the planes that might potentially be entered. “I can tell you what I think the best are and I can tell you in terms of size: Boeing 767, Airbus 330, Airbus 340, [Airbus] 300 and Boeing 777.” EADS is Airbus' parent company.

As the Air Force moves closer to launching the replacement program, both Kelly and Hoffman figure to have some say in the service's acquisition plans. A North Grumman-EADS team is expected to compete against Boeing for the contract.

“I think from an operational perspective the first best option is a mix of capabilities,” Kelly said. “There are advantages to a larger airplane than there are advantages to a medium sized airplane, so a mix would probably be a prudent way to try to find the right balance and where the sweet spot is,” the No. 2 AMC official added.

“I would differ with Gen. Kelly that I think we ought to buy one kind . . . just because development costs are cheaper, fleet management, all those things are cheaper, at least for the first tranche of aircraft, which I'm kind of defining as the first 100,” Hoffman said. He added that Congress has recently mandated that “the first 100 [tanker replacement aircraft] ought to all look the same, they all [should] be medium, we already have a high-low mix.”

The officials provided those comments after subcommittee member Rep. Gene Taylor (D-MS) asked them for their personal opinions.

This ongoing debate over the size of the aircraft has riled what once was widely considered a medium-sized tanker competition.

The Northrop-EADS team has primarily pitched the conceptual A-30 tanker aircraft; Boeing has chiefly touted its KC-767 aircraft. With scuttlebutt flying in Washington that the AOA may lead the service to pursue a larger plane than originally anticipated, both companies have altered their public pitches to include larger aircraft. The two companies have cited the aircraft examined in the AOA as possible substitutes -- or additions -- to their anticipated proposals.

As the medium vs. large vs. mixed buy debate picks up steam, several defense analysts contacted March 1 noted the service already has several sizes of flying gas stations.

“What seems to escape everyone's attention is that we operate a mixed fleet today,” Christopher Bolkcom, an analyst with the Congressional Research Service, said. The Defense Department's “aerial refueling capabilities are composed of large tankers (KC-10s), medium tankers (KC-135s), and tactical tankers (KC-130Js).

“The different tankers in today's fleet have diverse capabilities, which makes the entire fleet more robust and capable,” he added. “It would appear clear that maintaining a mixed fleet in the future would be attractive, if it can be afforded -- a mixed fleet typically costs more to operate than a homogeneous fleet.”

Another analyst, Loren Thompson of the Lexington Institute, said he feels the Air Force seems confident it possesses adequate aerial refueling capability for missions in the Middle East, “but there's a gap” for how they would tank during Pacific operations. To Thompson, that means range could emerge as the service's most-pressing requirement.

For missions in that region of the globe, “they would need a plane that has range and heavy carrying capacity,” Thompson said.

Meantime, defense officials this week said the Air Force is likely to soon receive approval from Pentagon acquisition officials to move forward with the replacement program. To that end, Kelly told reporters during a 30-minute pause in the hearing that the Air Force is likely “one week . . . to a month” away from releasing a request for information, which would mark the formal start of the replacement effort.

Air Force Chief of Staff Gen. T. Michael Moseley told reporters the next day on Capitol Hill that service officials have signed off on a version of the RFI and passed it on to Deputy Defense Secretary Gordon England and the document is “up there on his desk.”

Kelly and Hoffman, jointly fielding questions from reporters during the break of the Feb. 28 hearing, agreed the service will not be able to release an RFP for six months. The next day, Wynne confirmed that time line, saying he expects to issue an RFP in September.

The Air Force and Pentagon have been tight-lipped about most details on the pending competition -- from when it will formally be launched to the list of requirements to which industry proposals must adhere. The Pentagon has yet to finalize its tanker replacement requirements, service officials have said. That has left industry wondering and relying on internal projections of those requirements to prepare their proposals.

Because industry officials have not seen the AOA or a request for information, both the Northrop-EADS and Boeing teams have said they are basing their work on the requirements the Air Force highlighted during the failed 2002 KC-135 replacement effort and other requirements they suspect the service has since tacked on (ITAF, Sept. 16, 2005, p1).

An Air Force official contacted this week said the RFI likely will contain few actual requirements. “That'll be very broad, probably,” the official said, noting a forthcoming capabilities development document (CDD) and the RFI “are where industry will really get a good look at the requirements.”

Meantime, the Feb. 28 hearing marked the first public disclosure of the issues the AOA examined and several key conclusions which were delivered to the panel by Kennedy.

“We found all the [airframes examined] enough in our analysis that we could not exclude them and in particular we found that moderate changes in the underlying commercial aircraft price could move them as to which turned out to be most cost effective,” Kennedy said.

The RAND-led study team examined developing a completely new aircraft, but concluded that buying an existing aircraft and converting it into a tanker configuration would be more “cost effective,” Kennedy noted. The study also included expected advancements in defensive and electronic warfare systems, he said.