The US Federal Aviation Administration (FAA) has been vocal about efforts to integrate unmanned air systems (UAS) into US airspace, but details in the agency's new plan reveal the path to full integration will be long and technically challenging.

“FAA experience to date with the development of [proposed rules] for small UAS indicates that UAS rulemaking efforts may be more complex, receive greater scrutiny, and require longer development timeframes than the average regulatory effort,” says the FAA’s 7 November report, which was required by the FAA Modernization and Reform Act of 2012.

The act also stipulates that the plan outline steps to accelerates UAS integration and “provide” for safe UAS integration by 30 September 2015.

FAA Administrator Michael Huerta told reporters 7 November that the agency has already made progress with UAS integration and that some 7,500 small UAS could operate in US airspace within five years .

And the report notes that the FAA expects some work to be complete by 2015. For example, it expects to have established a certification processes for a few UAS operators and certification requirements for pilots and crew of small UAS.

But priorities needed for widespread integration of UAS will likely take years longer, says the agency.

Those include developing, testing and certificating “sense and avoid technology” that will allow UAS to avoid colliding with other aircraft.

“Due to complexity, significant progress in [airborne sense and avoid concepts] is not expected until the mid term” says the report, which defines “mid term” as within five to 10 years.

The report says FAA will not approve ground-based sense and avoid systems for use by public and educational UAS operators until between 2016 and 2018. Likewise, the FAA likely won’t certificate airborne sense and avoid technology until between 2016 and 2020, the report says.

The FAA also faces the formidable task of establishing standards and regulations pertaining to airworthiness, technical and communications systems, operating environments, pilot qualifications and other topics, according to the report.

For example, regulations and guidance materials related to UAS control and communication systems likely won’t be finished until between 2016 and 2017, the agency says.

“To gain full access to the NAS, UAS need to be able to bridge the gap from existing systems requiring accommodations, to future systems that are able to obtain a standard airworthiness certificate,” says the report. “These UAS will also need to be flown by a certified pilot in accordance with existing, revised, or new regulations.”

The FAA also must conduct research before establishing standards, and it says it may not finish studying required functional and performance capabilities until 2017.

The agency also must study human factors to help determine best procedures for air traffic controllers, says the report. By 2020 the FAA hopes to have conducted UAS training at air traffic control facilities throughout the country.

Major differences between UAS and manned aircraft also mean regulations must a address a myriad of minute regulatory details.

For instance, current regulations set security standards for cockpits doors, but don’t define what a cockpit is or where it is located, says the report.

“This presents a challenge for UAS considering that the cockpit or ‘control station’ may be located in an office building, in a vehicle, or outside with no physical boundaries,” says the report. “Applying current cockpit door security regulations to UAS may require new rulemaking, guidance, or a combination of both.”