Negotiating the plethora of rules around carry-on liquids can leave a traveller in need of a drink.
YOU walk smugly out of the airport duty-free shop with a couple of bottles of cheap alcohol … only to have them taken away at the next security checkpoint.
Travellers are being repeatedly stung by confiscations of duty-free as the regulations are inconsistently applied at airports around the world.
Passengers are losing duty-free purchases travelling into and out of Australia and at different stages of their journey, as they struggle to make sense of the system.
The Sun Herald receives numerous letters from readers bewildered at having fallen foul of regulations - and angry at being left out of pocket.
One reader reported that duty-free alcohol purchased at Sydney Airport was confiscated in Singapore because shop staff did not put it in a sealed bag.
Another reader bought a bottle of duty-free liquor at a shop near their boarding gate in Bangkok and had it confiscated minutes later as they boarded their flight to Australia.
Many travellers assume that they are free to buy duty-free once they have passed through airport screening but much of what is confiscated is being taken at secondary checkpoints.
And while the staff in duty-free stores are supposed to advise travellers according to their destination, there is widespread confusion about the rules and how they should be applied.
Sydney lawyer Michael Cooper bought two bottles of duty-free whisky at London's Heathrow Airport after he had checked in his baggage and cleared all the security checks.
He had no problems when boarding his flight at Heathrow but had the whisky confiscated during a brief transit stop in Singapore, even though he did not leave the secure section of the airport.
He was told by security staff it was because the bottles were not packaged in a tamper-proof sealed bag.
Cooper and his wife emailed a complaint to the duty-free store in Heathrow and received a different explanation, with the response saying that due to Australian government regulations, liquids cannot be taken into Australia unless they are ''purchased at the last port of call'', which in Cooper's case would have been Singapore.
''Consequently you were not able to purchase liquids from Britain if Australia-bound,'' the response from the store stated. ''Our team member clearly made an error when assisting you with your purchase.''
Cooper says he did get a refund for his purchases … but would have rather had the whisky. ''It is all very confusing and we would have never bothered buying it at the duty-free if we had known,'' he says.
It is important to understand that the issue relates to liquids and security rather than duty-free concessions: regulations restricting liquids carried on international flights to a maximum of 100 millilitres an item have been in place for several years.
Perfumes and beauty products are generally not a problem as the duty-free shops tend to sell 100 millilitre bottles but alcohol can be a minefield.
Rules regarding packaging and where and how duty-free items are purchased vary from country to country and are not always clear to passengers.
Australian Customs, for example, has a section on duty-free in its ''Know Before You Go'' guide for travellers that states: ''If you are aged 18 years or over, you can bring 2.25 litres of alcohol duty-free into Australia with you'' - without mentioning that it is subject to regulations about liquids and must be purchased or carried according to strict rules.
A spokesman for the Department of Infrastructure and Transport, which is responsible for security at Australian airports, says travellers can best avoid having duty-free purchases confiscated by buying it before they check in for their flight, so they can pack it in their checked baggage.
''Or, for last-port-of-call airports to Australia, by having it delivered directly to the departure gate,'' the spokesman says.
However, he notes that some overseas airports are not willing to do this, ''in which case passengers may wish to reconsider purchasing duty-free products''.
If you do want to buy duty-free alcohol to carry on as hand luggage, make sure the shop assistants are aware of your full itinerary, including any stopovers and onward flights. If you show them a boarding pass that only applies to the first leg of a multileg journey, they may give you the wrong advice.
Ask if alcohol purchases can be delivered to your departure gate, and always ask for purchases to be packaged in a ''tamper-proof'' sealed bag. Duty-free shops do not always do this as a matter of course but will do so on request.
If there is any doubt, you can buy duty-free when you land back in Australia; ''ready for collection'' purchases can be pre-ordered online or purchased within an airport store, between landing and going through Customs.
The good news is there is hope for easier times ahead, with the Australian government trialling several new technologies to detect any explosives in liquids and aerosols.
''The outcomes of this trial will contribute to international efforts to remove liquid restrictions on international flights in the future,'' a government spokesman says.