The unions said they were downing tools after management made "very vague promises" in negotiations during the last strike between June 11 and 14.
Pilots say that new pay rules decided by management in June would lower their salaries by five percent. The previous strike grounded around 20 percent of flights -- mainly to mid-range destinations.
Management said only a quarter of pilots went on strike earlier this month but unions said the figure was more like seven in 10.
The latest strike is the latest industrial action to hit France, which has been gripped by social unrest over a series of disputed labour reforms the Socialist government of President Francois Hollande is trying to force through.
However, despite strikes by pilots and railway workers, there has been relatively little disruption to fans travelling around France for Europe's showcase football tournament.