South Korea will have a homogenous force of 16 upgraded Lockheed Martin P-3 Orion maritime aircraft by 2018 under an L-3 and Korean Air Lines program to refit eight aircraft that remain unmodernized.

Separately, the South Korean navy is seeking 20 more maritime aircraft, which would considerably augment its anti-submarine capability.

Work began in April on P-3Cs that South Korea has operated since 1995, says Ernie Lock, L-3’s program manager. The U.S. company is due to deliver its components for the first aircraft within 22 months; the last unit should be upgraded within 60 months. The defense ministry values the program at $400 million, including manuals and training.

The aim is to bring the aircraft to the same specification as eight P-3Bs that Korea Aerospace Industries and L-3 upgraded to a standard called P-3CK last decade. The P-3Cs are newer, but having been built two decades ago, lack the advanced equipment retrofitted to the P-3Bs.

In upgrading the P-3C, the partners will completely renew the electronics suite, installing a new magnetic anomaly detector, electro-optic sensor, radio detection gear, radar, self-protection suite and data link. The systems is built around a data management system with seven operator stations plus a tactical display in the cockpit. L-3 declines to discuss weapons.

L-3 is building the equipment at its Greenville facility in the U.S. Installation will be done at Korean Air’s Gimhae works. Whereas the airframes of the P-3Bs were extensively refurbished, Korean Air and L-3 are not working on the structure of the P-3Cs, except as necessary to install the new equipment. Electrical and cooling requirements are no greater, and possibly less, than those of the old electronics.

L-3 is offering the same maritime warfare suite for installation in a maritime version of the Bombardier Q400 turboprop airliner, the Q400 MPA, but that aircraft is not mentioned as a candidate for the navy’s requirement for 20 more maritime aircraft. The South Korean joint chiefs of staff have approved the navy’s request for the aircraft, which would serve alongside the Orions, says Yonhap news agency, quoting a military source.

The Defense Acquisition Program Agency sees prospective aircraft as the Boeing P-8 Poseidon, Lockheed Martin SC-130J Sea Hercules and Airbus Military C295. Listing the C295 and Poseidon as mutual alternatives is unusual, given the vast differences in flight characteristics, system performance and cost between the 86-metric-ton (189,000 lb.) jet and 23-ton turboprop.

While the program seems not yet to have approved funding, the military is proposing it as a response to North Korea’s submarine force. A North Korean submarine torpedoed and sank the South Korean corvette Cheonan in March 2010; 46 sailors died. North Korea has about 70 submarines, a South Korean board of inquiry reported after the attack. Most are small and all rudimentary, but they are hard for South Korea to find.

The estimated budget for new maritime aircraft is 1 trillion won ($900 million), which will certainly not cover 20 Poseidons nor even SC-130Js, whose design is offered by Lockheed Martin as a maritime development of the C-130J Hercules transport. That leaves the C295 as a likely candidate if the budget is not increased.