On Nov. 30, 2011, U.K. Border Agency (UKBA) staff will be involved in a public sector strike. As a result, guests arriving at London Heathrow Airport will experience long queues and delays at passport control. The strike will also affect Gatwick Airport and could affect flights in and out of the London area's other three airports, Stansted, Luton and City, which handle many flights to and from continental Europe.

If you are heading to or through Heathrow, you should contact your airline or tour operator immediately for an update. Every airline is reacting differently, with some saying it is still business as usual and not cancelling any flights or making changes at this point. Emirates, however, has cancelled some flights but is keeping one inbound and one outbound going. British Airways is not planning to cancel any flights, but is allowing people to make changes to flights free of charge to avoid connections in Heathrow on the 30th.

Air Canada is allowing people to change their flight free of charge to another date between November 28 and December 7, 2011 (inclusive) if you are booked for travel to London-Heathrow on November 29th or 30th, or you are booked for travel from or through London-Heathrow on November 30th. Air Canada will also allow you to change dates or, if you prefer to keep your travel date, change your gateway airport if there is availability. In other words, if you want to go to Frankfurt and try connecting though there, you can. http://www.aircanada.com/

If your flight is cancelled Air Canada will refund your ticket, although they do not anticipate having to cancel any flights.

If you can't change your plans Heathrow has promised to have trained staff on hand to provide 24-hour support for passengers in the terminals, offering information, extra seating, food and drink and activity packs for children. Look for people dressed in the purple uniforms – they'll be equipped with tools including iPads and mobile phones to keep passengers up to date. Free Wi-Fi will also be available to arrival passengers throughout Heathrow, with regular updates being posted here:

Heathrow Express will also be running additional half-hourly night services on Wednesday, November 30 through to Thursday, Dec. 1 between 23:53 and 03:03.

What should you expect in terms of compensation?

Each airline has different terms of carriage. Generally, if delays occur airlines must offer food and drink to passengers and accommodation if necessary. But don't expect any extra compensation beyond that -- a strike is beyond the airlines' reasonable control.

That said, because of this unique situation most airlines do seem to be offering a full refund if they end up cancelling your flight.

If you purchased travel "interruption" insurance prior to the date the strike was announced, you will also have more coverage available to you.

In both these cases, double check directly with your air carrier and travel insurance provider.