Australia's labor tribunal, Fair Work Australia, early on Monday blocked Qantas Airways and unions for its pilots, engineers, baggage handlers and caterers from taking any further industrial action against each other.

Following is what happens next:

* Qantas must scrap a plan announced on Saturday to lock out workers from Monday night and get its planes back in the air after grounding its entire fleet over the weekend. The airline resumed flights on Monday afternoon after clearance from the aviation safety regulator.

* The Australian and International Pilots Association, the Australian Licensed Aircraft Engineers Association and the Transport Workers Union, in talks with Qantas over the past 18 months, are no longer allowed to stop work, strike or take other actions like overtime bans.

* The airline and the unions must negotiate an agreement within the next 21 days. If they make good progress but have not reached an agreement in that time, they can seek an extension for a further 21 days. If they fail to reach an agreement, they will be forced into binding arbitration.

* Fair Work Australia would appoint a "full bench" to arbitrate.

* This is the biggest case since the Fair Work Australia law was enacted in 2009 where the tribunal has ordered a halt to industrial action and forced parties to negotiate. "In that sense, it is a test case," said industrial relations expert Joe Isaac, a former professor at Melbourne University.

* Key claims from unions: pay contractors equal wages with same conditions as Qantas aircraft engineers and baggage handlers, keep specific jobs in-house, pay pilots on Qantas code-share flights the same as Qantas pilots.

* Two industrial law experts said Fair Work Australia would not be able to stop Qantas from moving operations offshore and cutting costs.

"I don't think it can prevent Qantas from contracting out services and from moving services. It would be a very brave arbitrator to step across that line," workplace law expert Ron McCallum told ABC Television.

He said Fair Work Australia may give unions a win by saying that Qantas must consult before moving jobs offshore.