An airline employee whose duties involved loading and unloading baggage and cargo onto and from airplanes that flew interstate routes was an employee engaged in interstate commerce and thus the FAA did not apply to the arbitration clause in his employment agreement.  9 USC 1 exempts a class of workers–not a class of their employers; so the fact that Southwest is engaged in interstate commerce doesn’t matter.  What matters is whether the employee is one of a class of workers whose duties are directly involved in moving people or goods across state lines.  Workers who load and unload cargo from vehicles that cross state lines are directly engaged in interstate commerce and so are exempt from the FAA.