Members of the Unite union have voted to go on strike at the six UK airports owned by BAA.
As yet, no strikes have been set. But if industrial action does go ahead, it would lead to major disruption for the 300,000 passengers a day who use BAA's airports - Heathrow, Stansted, Glasgow, Edinburgh, Aberdeen and Southampton.
Conciliation service Acas will bring the two sides together for talks on Monday to try to find a way to avert the stoppages.
Would airports have to close?
Yes. BAA has confirmed that if strikes do take place, it would have to close all its airports on any day or days of walkouts.
This is because firefighters, security staff and engineers have taken part in the ballot, and airports cannot operate without any of these three key groups.
This would mean 300,000 passengers and about 2,500 flights a day not being able to either land or take off at BAA's airports.
What is the dispute about?
In a word, money. BAA is offering staff a 1% pay increase plus 0.5% linked to changes to the current agreement on sickness.
The Unite union says that this is not enough - particularly as staff have already had a pay freeze in 2009.
There is also a row about a bonus of £450 linked to targets which BAA missed by 3% in 2009.
The union thinks there should be some financial recognition given to staff for improved performance as the targets were only narrowly missed.
The company has also said there would be no additional summer bonus this year, which is usually paid if BAA makes a profit, and is worth about £700.
Who is involved?
In addition to security officers, engineers and firefighters, workers in various support roles have been asked to cast their vote.
When could a strike begin?
The union has to give a week's notice of any strike action. Its leaders are due to meet on Monday to decide on the dates and length of any strike action.
That means walkouts could start during the week beginning 23 August.
Some commentators have suggested that the Unite union may target the August Bank Holiday weekend that starts on Saturday, 28 August.
That would clearly have the biggest impact.
What are the chances of the strike going ahead?
Hundreds of thousands of people booked to travel in the next few weeks will certainly be hoping that an agreement can be reached to avert action.
There is some positive news for you if you are one of them. Both sides have agreed to take part in talks on Monday to be brokered by the conciliation service Acas. But we'll have to wait and see what the outcome is.
No union action has ever completely closed its airports in the past.
In the last planned walkout in 2002, action was called off at the last moment when an improved offer was made.
Are there any alternative options for travellers?
For passengers who haven't already booked flights, they do have the option of flying from non-BAA airports such as Manchester, Birmingham, or Gatwick. The latter was previously owned by BAA, but it was forced to sell it last year following a ruling by the Competition Commission.
What if my flight is booked from a BAA airport?
If your flight is cancelled by strike action by BAA staff, your airline will generally offer you either a refund, the chance to rebook, or possibly rerouting via an alternative airport.
This has been the case in the past when airlines have been affected by strike action which has not been carried out by their own employees.
However, if your flight is set to be affected by BAA walkouts, you should contact your airline as soon as possible.
What if I have booked a package holiday?
If you booked a package holiday, then the travel agent or operator has a responsibility to provide all the elements of that package.
So if BAA strike dates are announced, affected passengers should contact their agent or operator as soon as possible.
The agent or operator will try to find alternative flights but, if that is not possible, will refund the cost of the whole package holiday.
The Atol protection scheme run by the Civil Aviation Authority does not kick in because this is designed for when a tour operator goes out of business.
Can I claim on my insurance?
For those who booked the separate elements of their holiday themselves, the picture is slightly more gloomy.
If their holiday is cancelled, they will need to try to claim back any hotel, hire car or other costs through their travel insurance. Some will pay out, but some will not.
The small print in the insurance documents will explain exactly what cover is offered in the event of a strike delaying or cancelling fights, although some insurers do give leeway.
Anyone claiming would need to have bought the policy and made their bookings before any BAA strike dates were announced.
Travellers who book a flight - knowing that it is during a strike period - will not be covered by insurance if it is cancelled.
Alternatively, if it was booked on a credit card, then they might have a claim through their credit card provider for costs of over £100. This comes under section 75 of the Consumer Credit Act.