The FAA, sticking to the U.S. Transportation Department (DOT) plan laid out to cope with a prolonged partial government closure, has called in more than 800 Office of Aviation Safety employees responsible for both field inspections and certification of “critical” products.

The recalls include more than 600 Flight Standards staffers, including safety inspectors, and 200 Aircraft Certification service employees, the FAA says. The agency also called in a handful of physicians and support staff in its Office of Aerospace Medicine to support industry drug and alcohol testing programs.

“As the government shutdown continues, the agency will determine whether additional employees need to be recalled to provide oversight of potential risk,” the FAA says in a statement. “Over the course of the government shutdown, the FAA expects to recall support staff to address emergency needs.”

The FAA’s aircraft registry office—declared “essential” during the 1995-96 government shutdown—remains closed, meaning aircraft ownership cannot legally change hands, new planes cannot be registered, and existing registrations, which expire at the rate of about 10,000 per month, cannot be renewed. The situation has at least two airliners—a JetBlue Airways Airbus A321 and a US Airways Airbus A330—stranded in Hamburg and Toulouse, respectively, awaiting paperwork that will clear them for delivery to their carriers. Both airlines were scheduled to take possession of their aircraft last week.

The National Business Aviation Association (NBAA) tells members that the FAA has not adopted a so-called “mailbox” rule that would allow duplicate registrations and bills of sale mailed to FAA to serve as an alternative registration process.

“While mailing an application may allow owners to fly on a ‘pink copy’—temporary authorization to fly in U.S.—this likely does not mean rights in the aircraft are properly perfected,” an NBAA statement says. A pink copy is a 90-day authorization for intra-U.S. operations only, the association notes.

The DOT surprised many by including the 3,000 FAA Flight Standards inspectors in the original count of 15,500 FAA employees furloughed when the government partially shut down Oct. 1. However, the DOT’s plan, released Sept. 27, noted that about 2,400 inspectors and other key staff would be brought back “incrementally” over a two-week period if the shutdown persisted.

The Professional Aviation Safety Specialists (PASS), which represents many of the safety employees furloughed, says that the recall—while an improvement—still leaves the industry at risk.

“PASS appreciates the FAA working within the constraints of this government shutdown to bring back critical safety employees, but we stand firm in the belief that all 3,000 aviation safety inspectors need to be back on the job immediately,” a union spokeswoman says. “Before this shutdown, understaffing of the aviation safety inspector workforce was a serious issue; now, for every minute these inspectors are off the job, the backlog of their oversight and surveillance continues to grow.”

While a skeleton crew of aviation safety employees means most of the division’s work halts, the furloughs have not stopped everything. Participants in the FAA’s delegation programs, which rely on FAA-approved teams made up of private-sector employees, continue to work on their certification and flight standards-related projects, notes Aeronautical Repair Station Association Executive Director Sarah MacLeod.

“There should be a bang-up business going on for persons with delegated authority—designated airworthiness representatives, designated engineering representatives and the like,” MacLeod says. “While the process for obtaining a delegation is slow and painful, when granted within the proper parameters the ability to issue approvals and authorizations without the direct involvement of an FAA employee is essential to the continued operation of a business.”

So far, U.S. airlines have voiced little public concern over the shutdown. An Airlines For America (A4A) spokesman says the association “is still evaluating impacts,” but has been advised by the FAA, the U.S. Transportation Security Administration, and Customs and Border Protection “that front-line employees would not be subject to shutdown-related furloughs that would affect the traveling and shipping public.”

A4A is aware of shutdown-related challenges like aircraft delivery delays, but is “confident safety will not compromised.”

The NBAA and other general aviation advocates are at a different place on the spectrum.

Halting aircraft registry service alone “is effectively grounding the general aviation industry, severely jeopardizing countless jobs, and America’s economy and infrastructure,” NBAA President Ed Bolen told President Obama and congressional leaders in an Oct. 7 letter.

“We are pleased that the FAA is recalling 800 furloughed Aviation Inspectors and we are hopeful that these numbers will increase in the coming days,” the National Air Transport Association (NATA) tells members, adding, “We know that the lack of registration activity is harming many of our members’ businesses.”

NATA planned to join other industry groups in a direct appeal to DOT Secretary Anthony Foxx to re-open the FAA’s registry office.