The US Navy makes more efficient use of open source technology in complex unmanned aircraft than its counterparts in the Army and Air Force.

That was but one of the conclusions of a recent Government Accountability Office report that looked at the use of open source systems in developing advanced military drones.

From the GAO report: The services vary in the extent to which they have adopted open systems for DOD's 10 largest unmanned aircraft, with the Navy leading the other services. Three of the Navy's four current and planned unmanned system programs incorporated, or are planning to incorporate, an open systems approach from the start of development in key components of their Unmanned Aircraft System (UAS)-the air vehicle, ground control station, and payloads such as cameras and radar sensors.

Conversely, none of the Army or Air Force drone programs incorporated the approach from the start of development because, according to Army and Air Force officials, legacy unmanned programs tried to take advantage of commercial off-the-shelf technology or began as technology demonstration programs, the GAO stated. That decision however has led to cost over-runs and upgrade difficulties.

[MORE: What the drone invasion looks like]

The GAO noted that several of programs are starting to incorporate open source, primarily for the ground control station of aircraft during planned upgrades.

"For example, the Army did not initially include an open systems approach for its three UAS programs, but has since developed a universal ground control station with open interfaces that each of its programs will use. None of the Air Force's three UAS programs were initially developed as an open system, and only one is being upgraded to include an open systems approach. Each of the programs that have adopted an open systems approach expects to achieve cost and schedule benefits, such as reduced upgrade costs and quicker upgrade times."

Some other interesting items from the GAO open source drone repot included:

Three of the Navy's four current and planned UAS programs-the Small Tactical UAS (STUAS), Triton, and Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS)-which are less than 5 years old, included or are planning to include an open systems approach from the start of development for the key components of their systems. The Navy expects significant benefits in return, such as reduced development and integration time and costs, as well as increased future competition for new system payloads.

In addition, program and contractor Navy officials noted that by having the rights and specifications to the payload interfaces, the program will be able to integrate and test third-party designed payloads within a matter of days or months, as opposed to years typically required to test new system payloads. Program officials also anticipate that they will be able to independently integrate at least 32 different payloads developed by 24 different manufacturers.

The Army's three UAS programs-Hunter, Shadow, and Gray Eagle-were all initially developed as proprietary systems and did not include an open systems approach for all three key components-the air vehicle, ground control station, and payloads. Moreover, the Army's UAS ground control stations limited interoperability and resulted in the Army paying for ground control stations that provided similar capabilities.

The Army eventually developed a common ground control station for the three UAS; however, the new station was still proprietary. All three of the Army's UAS programs are now upgrading to a universal ground control station that incorporates an open architecture to address obsolescence issues and increase interoperability. According to Army program officials, ground control stations require continuous hardware and software upgrades as the technology becomes obsolete. Even though an open systems approach is being incorporated later in the programs' life cycles, officials believe the benefits-reduced obsolescence issues, reduced upgrade costs, and increased interoperability-outweigh the costs. For example, the Army's new universal ground control station will give Army operators in the field the ability to fly Hunter, Shadow, and Gray Eagle from one ground control station. This was not possible with the Army's legacy ground control stations that did not use open architectures.

The Air Force has had limited success in modernizing its UAS to include open systems. For example, the Reaper plans to upgrade to an open ground control station, but the remainder of the system remains proprietary. The other two programs-the Predator and Global Hawk-included language in their planning documents stating their intention to introduce open system elements later in their respective life cycles. However, Predator's age and Global Hawk's fiscal constraints prevented them from adopting an open systems approach. As a result, the two systems remain largely proprietary and are now facing challenges sustaining and upgrading their systems.

The Predator program began in 1994 as an advanced concept technology demonstration program and is one of the oldest systems in DOD's UAS portfolio. Program officials stated that the Predator's software is not modular and the program has no intention of modifying the software because the Air Force is planning to divest itself of Predator aircraft once more Reapers are fielded. Predator officials also noted that sustainment and obsolescence challenges remain a risk area for the program.

Officials from the Global Hawk program, which started development in 2001, also stated that obsolescence is a major problem for that program, particularly for the ground control station. The program recently had planned to develop a new ground control station that utilized an open systems architecture. However, the Air Force cancelled the upgrade effort in 2013 due to what program officials described as fiscal constraints, even though it plans to use the aircraft through at least 2032. The Air Force is now planning to continue to maintain the legacy Global Hawk ground control station and communications system, but it will require upgrades and costly support.

[NEWS: The weirdest, wackiest and coolest sci/tech stories of 2013 so far]

The GAO said that while the Department of Defense has policies that direct programs to use an open systems approach, the Navy is the only service that largely followed the policy when developing its UAS. "In addition, while new open systems guidance, tools, and training are being developed, DOD is not tracking the extent to which programs are implementing this approach or if programs have the requisite expertise to implement the approach. Navy UAS program officials told us they relied on technical experts within Naval Air Systems Command to help develop an open systems approach for their programs. Until DOD ensures that the services are incorporating an open systems approach from the start of development and programs have the requisite open systems expertise, it will continue to miss opportunities to increase the affordability of its acquisition programs," the GAO stated.

In the end the GAO recommended that the Air Force and Army implement open systems policies, DOD develop metrics to track open systems implementation, and the services report on these metrics and address any gaps in expertise. For its part, the DOD partially concurred with the GAO but stated that its current policies and processes are sufficient.

Follow Michael Cooney on Twitter: nwwlayer8 and on Facebook

Check out these other hot stories:

Common car lubricant speeds imaging apps 10X

Just when you thought it was safe to go to the bathroom - toilet malware strikes

Colliding, exploding stars may have created gold on Earth

Small, electric-powered nano-lasers may help keep Moore's Law valid

High-tech tool can help interpret health clues from crying babies

Cyber rogues aren't the only threat to energy supply, changing environment offers plenty of challenges

NASA wants to bring back hunks of Mars in future unmanned mission