Hundreds of people flying into Britain from the Middle East on Wednesday may see their travel plans disrupted, as up to 18,000 border staff strike over public-sector pension reform. The UAE\'s two national airlines have cancelled five flights into and out of London in anticipation of “extensive delays”, after UK authorities warned of 12-hour waiting times. British Airways and Qatar Airways have not cancelled flights but have urged passengers to switch their flights and offered opportunities to rebook free of charge. “We are concerned that the UK Border Agency strike creates considerable uncertainty for our customers booked to fly into UK airports,” said a spokesperson for British Airways. Gatwick Airport alone expects 243 scheduled inbound flights today carrying around 29,000 passengers, 8,000 from outside the European Union where delays are most likely. Thousands of immigration officials are set to join union staff representing teachers, health workers and civil servants today, in a 24-hour strike over changes to public sector pension plans. The industrial action is expected to be the biggest union protest since the ‘Winter of Discontent’ in 1979 that helped Conservative leader Margaret Thatcher rise to power. Analysts warn extended strike action could heavily impact airlines’ profits, as carriers are forced to rebook or cancel flights to accommodate the disruption. “Costs for airlines may run into several hundred thousands of dollars for changing passenger flights and providing accommodation,” said Saj Ahmad, a Dubai-based aviation analyst. “Further public sector strikes are unlikely to happen before the end of the year. But that said, there are plans for more frequent and sustained walkouts in 2012 although no dates have been announced or agreed.” Travel agents said Wednesday they feared a ripple effect in an already struggling tourism industry. The aviation has seen a wave of strike action this year, following labour disputes with Australian national carrier Qantas, and British Airways. “The border control strike creates a significant setback to the UK economy, as well as many European and international carriers; with some minor spill-over effect on other countries,” said Basel Abu Alrub, managing director for Dubai-based travel agency U Travel. “There is not enough capacity to absorb a long grounding of major route services going into and out of London. This will also create a backlog in flights as passengers are trying to go home for the holidays, with many seeing their London connection being cancelled and forced to re-route via another country. “This problem is a major issue that needs to be addressed very quickly.”