The third bidder for the KC-X tanker contract, U.S. Aerospace (USAE) and its Ukrainian partner Antonov, had their protest denied yesterday by the Government Accountability Office (GAO).

The company had filed the protest because the Air Force had said their proposal was delivered past the deadline for submission. U.S. Aerospace claimed that their courier was deliberately delayed and should have been allowed to make the delivery on time.

This decision leaves only the Boeing (BA) and EADS (EADS:P) bids as being considered for the contract. The Air Force had previously said that a decision would be announced around the middle of November but there have been reports that this might slip.

The KC-X new aerial tanker program Request for Proposals (RFP) attracted a third bid this time around. U.S. Aerospace submitted one based on the Ukrainian made Antonov transport. The question that immediately comes to mind is can this team win, or will it be Boeing (BA) or EADS (EADS:P)?

Realistically the chances of this bid being selected are low. The companies had asked for a sixty day extension to work on their proposal. The Air Force already slipping the contract deadline one month to accommodate EADS refused the further two month slip. This would have pushed award into 2011 with the current planned date of mid-November this year already late enough. The U.S. has been trying to get a replacement tanker for the aging KC-135 since 2001.

U.S. Aerospace and its partner obviously felt their proposal could be improved with the extra two months but did go ahead an turn one in that they feel meets all of the Air Force requirements. At the same time in a recent filing with the Securities and Exchange Commission (SEC) U.S. Aerospace makes clear that the Air Force could easily reject them.

The company writes “For any or all of these reasons, the Air Force may not select our bid, may disqualify our bid, or may refuse to consider it on the merits, or at all,” based on myriad factors. These include not meeting requirements, not having qualified sub-contractors, not having necessary facilities or capabilities and even missing the deadline. They didn’t do that turning one in on time.

Of course all of this could be standard “Forward Looking Statements” meant to make clear to anyone investing in their stock that they are being conservative in their estimates. The stock was trading at 18 cents at the close on Friday.

Certainly they have offered a cost effective approach. The Air Force must consider if it meets their requirements and they have the ability to produce the systems to the necessary schedule. Certainly stranger things have happened in defense contracting.

Boeing (BA) submitted their proposal for the KC-X aerial tanker program a day after rival EADS (EADS:P) did. Today was the day it was formally due, EADS coming in a little early. The Boeing proposal stresses their cost and size benefits over competing EADS with their larger A330 based aircraft. Boeing is basing their bid on a modified 767 airliner with advanced avionics from the yet to enter service 787.

Also U.S. Aerospace and Antonov submitted their competing proposal after losing a bid to delay things sixty days. There total cost is under thirty billion for a contract the Air Force has estimated at $37.5 billion based on an aircraft cost of only $150 million each.

The Air Force plan is to award the contract in four months. The three bids may make the competition’s source selection last longer and may also raise the chance of a protest.

If the U.S. Aerospace / Antonov team wins it might get very interesting.

As reported last week U.S. Aerospace and Antonov intend to submit a proposal to the Air Force for the KC-X aerial tanker. Because the actual proposals are due this week supposedly the new team will ask for a sixty day delay to accommodate them. The deadline has already been moved once from June to July to allow EADS (EADS:P) and its team to bid.

The current schedule is for a contract award in November and this new extension would probably push that into 2011 due to the time it will take to evaluate a third bid. U.S. Aerospace did say that they will submit this week if no extension is granted.

A third proposal will make the contest more interesting especially as the Antonov will be very price competitive.

Update — Antonov is now a Ukrainian company, but in the days of the Former Soviet Union it made transports and utility aircraft for the “Russian” military, civil air companies and Warsaw Pact nations. My bad for being old school.

It came out today that there will be a third bidder for the Air Force’s new KC-X aerial tanker program. US Aerospace will propose a system based on Antonov platforms from Russia. There had been earlier rumors that the company would team with Ilyushin to offer a variant of the IL-86 airliner for this, but that had seemed to go nowhere.

Antonov makes large transport aircraft such as the AN-124 used to move outsize cargo across the world. According to US Aerospace they may offer a version of the AN-124 or an aircraft called the “AN-112″. The 112 is supposed to be based on earlier turboprop transport heavily used by the Soviet Union and its allies.

The submission of a third bid will change the competition quite a bit. A Russian based aircraft may certainly be cheap putting pressure on both Boeing (BA) and EADS (EADS:P) to review the cost of their proposals.

US Aerospace, similar to EADS, will assemble the aircraft in the U.S. and add the military specific equipment themselves. This will also include the flight refueling equipment.

They only have about two weeks to get a proposal together so if they do end up bidding it will be very interesting.

What less then a year ago seemed to be a program with only one company bidding, Boeing, now looks to have a chance to have three.

This program seems only to get more complicated.