I believe I have seen the future replacement for the E-8C Joint STARS fleet (shown pictured), and it's not going to be a US Air Force aircraft.

The US Navy is preparing to replace the EP-3E ARIES II, an electronic intelligence aircraft, with a new-start acquisition program called EPX.

But the navy's requirements for EPX call for an aircraft that would not only spy on enemy electronic signals, like the EP-3E, but also find and track moving targets, like the E-8C.

Interestingly, the EPX program of record will acquire 19 to 26 aircraft to replace only 11 EP-3Es flying today. At the high end of that range, 26 aircraft would nicely replace all 11 EP-3Es and all 17 E-8Cs in service. (One E-8C is a testbed, and doesn't count.)

If the air force can't pay for an E-8C replacement to appear after 2015, or even to modernize the radar on the current fleet, watch for the navy to steal this mission with the EPX. It's the roles and missions equivalent of a pick-pocketing.

And it's happened before. In 1998, the air force lost the EC-135 Looking Glass mission to the navy's E-6 take-charge-and-move-out (TACAMO) aircraft. Now, it's happening again, unless the air force acts very quickly.

This all became clear to me during my weeklong tour of Boeing's defense sites based in the Pacific Northwest. Paul Summers, Boeing's capture lead for EPX, briefed reporters about the navy's requirements, explaining that the size of the future EPX fleet had grown from 14-19 aircraft to 19-26 aircraft since last year.

The obvious question later occurred to me: Why does the navy need 26 EPX aircraft to replace 11 EP-3Es. Clearly, the navy has bigger ideas for this fleet.

Paul also discussed the new radar for the EPX. This in itself is noteworthy. The EP-3E does not have a radar. The aircraft intercepts and maps enemy communications and other electronic transmissions.

We've known for about a year that Boeing and Raytheon have installed the new littoral surveillance radar systems (LSRS) on a subset of the P-3C fleet, giving the navy its own mini-Joint STARS capability.

It is now clear that the LSRS is the proverbial trojan horse, injecting the navy into the Joint STARS business for the long-term.

Paul also explained that Boeing will consider the LSRS or another radar for EPX. The only possible alternative is a new variant of Northrop Grumman's wide area surveillance sensor developed under the multi-platform radar technology insertion program (MP-RTIP).

This will force Northrop to make a tough choice. Northrop, you see, is the prime contractor the E-8C, so it has everything to lose if the navy takes over the mission. However, if the company decides to join Boeing's EPX bid, that could be a signal that it believes the air force will never get around to replacing the E-8C.

The navy has money in the budget beginning next year to launch EPX. The air force has no funds to replace E-8Cs for the foreseeable future, and now faces a potentially disruptive leadership transition.

I'm not a betting man, but, if I was in Northrop's position, I know where I'd place my bet.

The air force has only itself to blame. The folly of the E-10 program, which spectacularly failed to combine an E-8C, and E-3A AWACS and an airborne operations center onto the same platform, has left the air force without a discernible plan to replace its aging fleets of 707-based aircraft.

The air force's only hope to stay in the E-8C business may be to observe the adage: if you can't beat them, join them.

Establishing a true "joint" partnership to acquire and operate a new fleet of narrowbody-class aircraft to serve all of the specialized missions performed today by 707s looks like the only way back in. (This idea also has the charm of making sense.)

Indeed, it has been proposed several times in the past. The only difference now is that the air force won't be calling the shots.

The navy, meanwhile, is not in this position merely through good fortune.

In 2004, the navy picked the Boeing P-8A -- based on the 737-800ERX -- to replace the P-3C, giving itself a versatile and capable platform to expand into new missions.

That's not to say that Boeing won't have to face challengers to win the EPX contract. The navy is inviting other companies to compete for EPX, but it will be difficult for the Airbus A320 and the Embraer E190 to overcome the incumbent advantages of the P-8A.

Paul Summers told us that Boeing had to make more than 50 modifications costing $1 billion to simply adapt the basic 737 airframe to meet the navy's more demanding certification requirements. The A320 and the E190 would face similar costs, possibly killing the chances for holding a fair airframe competition on EPX.

I expect that the navy will try to level the playing field in other ways. Perhaps, the navy will select the P-8A as the baseline platform and invite bidders -- including Boeing, Lockheed Martin and Northrop -- to compete for the systems integrator role.

-- Steve Trimble