The National Union of Metalworkers of South Africa said in a statement on Tuesday that it had met with the management of Comair on Saturday in an attempt to resolve the issue of salary discrepancies.
Comair operates British Airways and kulula.com in South Africa.
In Numsa's view, Comair management is not taking the issue seriously, despite two recent long meetings - one last Thursday and one on Saturday.
"Numsa has given a very clear direction about how they can fix this situation over a reasonable period of time. They refused. Their proposal will worsen the problem and result in the wage gap being widened for the lowest paid workers," stated Numsa.
Fin24 reported last week that the Labour Court reserved judgment in the matter of Comair's application to interdict a strike by Numsa on Thursday. Comair approached the Labour Court in a bid to interdict the strike after Numsa served the company with 48 hours' notice on Tuesday.
The Labour Court reserved judgment in the case and interdicted a strike by about 300 Comair ground staff.
According to Comair, the failure to reach an agreement now means that the parties will have to wait for the Labour Court to grant a final judgement on Comair's application for an interdict against a potential strike.
Numsa said on Tuesday that it expects to obtain reasons from the Labour Court this week on why it granted Comair a temporary interdict for the strike.
The union said, depending on what the reasons were, it would assist it to make a final decision on a possible way forward.
"We will also have to consult our members for a mandate," the union said. Numsa added that it would likely be meeting with Comair again "soon" to try to find common ground.
Comair said in a statement on Monday that its operations would continue after Numsa talks deadlocked.
Wrenelle Stander, Comair's executive director, said in the statement that the airline was "disappointed" a settlement could not be reached with the union.
The airline said it has "comprehensive contingency plans" in case of potential industrial action.
These include employees from around the business volunteering to assist at airports, pro-actively contacting customers to facilitate check-in and providing additional fast-bag-drop counters.
In January this year, Fin24 reported that Numsa claimed the wage discrepancy was unjustified and race-based, between workers for doing the same work.
In Numsa's view, 23 workers at the Airports Bargaining Unit are earning what the union deems to be unjustifiably high salaries.
The positions most affected are those of ramp controllers, lounge hosts, customer services agents and special services agents. The union says the widest salary gap for the same grade of work is over R7 000.
Stander at the time denied Numsa's claim that some Comair personnel are paid R7 000 a month more than their colleagues on the basis of race. Stander said the 21 "outlier" employees, whose salary scales differ from other colleagues in the bargaining unit, consist of people across race groups and genders and that Numsa has been informed of this.
According to Comair, the salary discrepancies of the 21 "outliers" are in some cases as little as R600, and in only one case is the difference R7 900.