Chief executive Julia Lo Bue-Said said the walkout – which will take place on Friday 28 April – was "disappointing" news for the travel industry.
"Fortunately, many of our travel agency partners are telling us that their customers are not currently being put off by the threat of strike action," she reassured.
"For anyone that is travelling during this period, whether it’s for business or leisure, we would strongly advise that they prepare as much as possible for longer wait times, use e-gates where possible and check airport and port websites before travelling to see if any strikes are likely to affect their journeys."
