"We don't believe we have imposed 'jailhouse' work rules," FAA spokeswoman Laura Brown told AVweb on Tuesday. She also disagreed with NATCA's claims of "inadequate staffing" at facilities around the country. "The 'authorized' number they quote is from a 1998 contract," Brown said. The FAA is working on a new set of numbers to determine appropriate ATC staffing levels based on statistical models, she said, and will release those numbers in March. She added that under the old NATCA contract, the FAA was not able to respond quickly enough to changes in traffic. Events such as the entry or exit of airlines at specific airports can drastically affect traffic very quickly. "Now we can be more flexible" to respond to such changes, she said. Brown said the FAA has plans in place to replace all the retiring controllers, train their replacements and increase the workforce by about 200 positions per year. She added that the FAA "always wants to reach a voluntary agreement" with workers, but in the case of the controllers' union "we followed the process ordained by Congress."