Companies that are furloughing pilots often offer "voluntary" furloughs to pilots on the seniority list that wish to be "furloughed" out of seniority. (IE a senior guy wants to explore other opportunities, so he asks to be furloughed prior to junior employees.

This is beneficial in several ways. First, it allows the company to release a senior employee which results in greater savings (pay wise) than furloughing a junior guy. Second, it allows the senior guy to follow other avenues or dreams, while still retaining the right to return down the road (with seniority of course). Finally, it potentially saves a job at the bottom of the list, reducing the number of "involuntary" furloughs.

There are several different methods that various companies use... for example, some voluntary furloughs might only be for a set period of time (say 1 year), others might be as "replacement" furloughees and last until the company starts to recall pilots. It all comes down to how the voluntary furloughs are negotiated between the company and the union.