What happens when a union goes on strike?
Employees have the right to strike to gain better wages, benefits, or working conditions. However, there is the potential that you might loose your job. If you are striking for economic reasons (i.e., protesting your workplace conditions or supporting your union's bargaining demands), your employer can hire a permanent replacement for your job. And when the strike ends, the replacement worker continues in the job and you, as a striking worker, are out of a job until a vacancy occurs.
If you are striking because of the unfair labor practices of your employer, more than likely you will not be permanently replaced and can demand immediate reinstatement when the strike ends.
If a collective bargaining agreement between the bargaining unit and the employer is in effect, and if it contains a provision that prohibits strikes (a "no-strike clause"), a strike during the life of the contract could result in the firing of all striking employees.