Staff at Heathrow airport are set to strike on the early bank holiday in May, with their union warning planes could be "delayed, disrupted and grounded".

It's part of a slew of strike dates by different departments at the UK's biggest airport over the next few weeks. Here's what you need to know about when all the strikes are, what disruption is expected and which airlines are affected.

Refuelling workers 50 refuellers working at the airport are set to strike on the following days: Saturday 4 May Sunday 5 May Monday 6 May (bank holiday) The Unite union says it expects the strikes by its members to lead to severe disruption for passengers over the bank holiday. Unite says the workers' employer, aviation fuel firm AFS, imposed cuts to the terms and conditions of new staff recruited since January 2024, including offering them reduced pension and sickness benefits.

Heathrow Airport says it is working on contingencies with AFS to manage any potential disruption, saying it has "robust" measures planned, adding that passengers can book flights from Heathrow with confidence. Sky News has attempted to contact AFS for comment.

Full list of airlines set to be affected: Air Canada American Airlines United Airlines Delta Virgin Atlantic Japan Airlines Emirates Qantas Elal Singapore Airlines Korean Airlines Air France Klm Ethiopian Airlines Jet Blue Lot (Polish) Royal Air Maroc Middle East Airlines Sas (Scandinavian) Tap Air Portugal Malta Airlines Dhl Aero Mexico Latam Airlines Air India Logan Air Bulgarian Air Uzbekistan China Airlines Air Mauritius Turkmenistan Avianca Asiana Saudi Tianjin Airlines Beijing Capital Rwanda Air Almost 800 staff in various departments Unite members in the following departments at Heathrow are set to take part in a week of strike action in May: Passenger services - who assist travellers to catch connecting flights Trolley operations Campus security - the security guards who are responsible for all workers at Heathrow and vehicles being checked before entering Heathrow Firefighters Airside operations The walkout will take place on the following days: Tuesday 7 May Wednesday 8 May Thursday 9 May Friday 10 May Saturday 11 May Sunday 12 May Monday 13 May Unite says the strike action "will inevitably cause widespread disruption across the airport, leading to delays and disruption". It says the airport has announced the work of passenger services, trolley operations and campus security is set to be outsourced by 1 June in a "cost-cutting exercise" that Heathrow says will save it £40m.

"This cost reduction will lead to a substantial reduction in the number of workers, which raises serious security concerns, given the safety critical nature of much of the work undertaken," Unite says. Its firefighters and airside operation members are also striking because they fear they "may be next in line" to have their work outsourced, the union adds.

Read more on Sky News:Train drivers at 16 rail companies to strike in MayWhich countries are unsafe to travel to amid Middle East tensions? Unite general secretary Sharon Graham said: "Heathrow Airport's actions are deplorable, it is raking in massive profits for the bosses while trying to squeeze every last penny out of its workforce. "Unite is fully focused on defending its members jobs, pay and conditions and our members at Heathrow will receive the union's unrelenting support during this dispute." A Heathrow spokesman said: "We are reorganising our operations to deliver better results for our customers.

There are no job losses as a result of these changes, and we continue to discuss with Unite the implementation of these changes for the small number of colleagues impacted. "Unite's threats of potential industrial action are unnecessary, and customers can be reassured that we will keep the airport operating smoothly, just like we have in the past." Border Force officers They will walk out for four days over changes to their working conditions, according to the Public and Commercial Services trade union.

The union said more than 300 of its members working at terminals 2, 3, 4 and 5 of the airport will walk out on the following days: Monday 29 April Tuesday 30 April Wednesday 1 May Thursday 2 May The effect of this strike would be on arrivals rather than departures. It's because around 250 Border Force staff will lose their jobs at passport control under new roster plans, the union says.

PCS general secretary Fran Heathcote said: "Our members are angry and disappointed at being forced out of their jobs. "While not everyone will be affected, the changes will disproportionately hit those who are disabled or have caring responsibilities.

"The Home Office should be doing all it can to retain experienced, trained staff - not lose them by introducing an unworkable new roster system." The Home Office said it was "disappointed" with the union's decision but added it remains "open to discussing a resolution". It added: "The changes we are implementing will bring the working arrangements for Border Force Heathrow staff in line with the way staff work at other ports, provide them with more certainty on working patterns, and improve the service to the travelling public.

"Keeping our borders secure remains our top priority and we have robust plans in place to minimise any potential disruption.".