An emergency meeting will be held at the reconciliation service Acas on Sunday in a bid to avert a strike at Stansted Airport in a dispute over pay.
Baggage handlers and check-in staff are due to hold a two-day strike over the August Bank Holiday weekend.
Union members voted three to one in favour of industrial action to secure an improved pay offer from Swissport.
TGWU and GMB union negotiators are due to meet airport ground-handling agents Swissport at The Stansted Hilton.
TGWU negotiators are included because they also represent staff involved in the dispute at Stansted Airport.
'Public suffered enough'
The GMB union has predicted that flights at the airport would be "severely disrupted" if the 500 workers walked out.
On Saturday, Gary Pearce, GMB organiser, said: "GMB hopes that Swissport are serious about this meeting and have prepared a suitable and acceptable pay offer that will settle the dispute.
"If not then the two days of strike action will unfortunately go ahead as scheduled."
A Swissport spokesman said on Friday: "Swissport as a responsible organisation believes that the travelling public have faced enough disruption and suffered enough difficulty throughout the past week with the security threats.
"They have therefore called on the unions to join them at Acas, to try and find a quick and agreeable resolution to this dispute."
The GMB said it submitted a pay claim in April, including calls for a premium rate for Sunday working in addition to a "substantial" pay review.
The union said Swissport had not met the claim for Sunday premiums and the pay offer they had put on the table included "unacceptable" strings attached.