Flight ET701, Heathrow to Addis Ababa: gosh, Third World airports are so stressful. I don't mean the graceful, spacious and efficient international terminal that awaits at the Ethiopian capital, but the national scandal that is Heathrow.

The shortcomings of our leading international gateway have been much discussed this year. How could a prosperous country be saddled with such a shambolic and poorly run piece of infrastructure? The airport owner, BAA, says it is forced to work within extremely tight constraints. "We're completely full and we have facilities that need to be refurbished," says Mike Forster, director of strategy and development. Things, as they say, can only get better: the splendid new Terminal 5, opening next March, will relieve capacity and provide space for revamping an airport that is of pensionable age. "Fundamentally, this is the key that unlocks the transformation of Heathrow, to the benefit of passengers and airlines," says Mr Forster.

So much for the future: what about now? Right now I am trying to find the Ethiopian Airlines check-in desk at Terminal 3. The exit from the Heathrow Central Tube station has a sign listing the zone from which each airline's flights depart. Zone G, it says. G as in "groan".

If you have been to Terminal 3 recently, you will share my discontent at seeing this sign. The Tube exit is by Zones A and B; Zone G is at the far end of the terminal. Furthermore, you are not allowed to walk straight there, for fear of adding to the congestion. Instead, you are signposted through a curious marquee arrangement that leads you out of Terminal 3 and around by the roadway to Zone G.

When you finally find Zone G, one thing you will not find is the Ethiopian Airlines check-in. That is because it is not in Zone G, but in Zone B – about 10 yards from where I started. That's B as in "bother", or perhaps a more robust oath.

The airline's staff are apologetic; yes, they have pointed out the error to BAA management, but nothing has been done to change the misleading sign. Luckily, I have allowed plenty of time, because the length of the security queue at Heathrow is one of travelling life's great uncertainties.

The government sees its role as supporting BAA. The Department for Transport has done its best to make life simple for the airport by introducing a unilateral ban on travellers taking more than one piece of hand luggage through the security checkpoint. Even so, Heathrow's hard-pressed security staff seem to find it hard to cope with the extra checks on hand luggage that were introduced last year. Tonight, the queue extends for much of the length of the terminal (hello again, Zone G) and getting through takes half an hour.

The official target for waiting time is 10 minutes. To find out why it should take three times longer, I decide to check how many of the scanners are being used at peak time on a Friday evening. Halfway through my impromptu survey, I am approached by a BAA official demanding to know what I was doing. I explain I am counting how many scanners were standing idle, thereby making the passengers stand idle.

"You shouldn't be doing that," I am told. "You don't have permission to work in this area." The answer, as far as I could tell as I scurry away, is that only 10 out of 15 are working.

Several conspiracy theories are doing the electronic rounds about why using Heathrow airport can be so awful. One increasingly popular myth asserts that it is actually a huge social experiment investigating how much stress humans can willingly undergo before air rage ensues. More plausibly, another theory suggests you and I are having our expectations managed by BAA. The worse the experience now, the more we will appreciate the new facilities; by underdelivering this year, the company hopes to intensify the happiness at finding that flying through Heathrow need not be an ordeal.

A third hypothesis is more convoluted, and focuses on the queues for security. On average, the waiting time is probably not much more than 10 minutes. But by under-resourcing terminals randomly and stretching the wait to half an hour, or more, BAA can profitably inject uncertainty into the miserable process. If travellers discover that the line for domestic departures one morning extends the length of Terminal 1, or that it inexplicably takes 40 minutes to get through the queue at Terminal 3 on a quiet Tuesday evening, you and I will have to build in yet more time for our journeys. On the many occasions when the queue turns out to be only 10 minutes, we will have a sharply increased "dwell time" in Departures, spending cash on everything from coffee to Cognac – to the considerable benefit of BAA.

Tempting though these may appear, I don't believe them. BAA's owners in Madrid, Ferrovial, have set some fierce financial targets after their £10bn acquisition of Britain's leading airports. And expenditure on extra security staff for the "peak of peaks", such as Friday evening, or for amending misleading signs, are costs that can be cut. So to try to enhance the experience for travellers with the good fortune to be heading for Ethiopia in future, I shall indulge in some "guerrilla signposting" when I touch down on my return flight. I shall take a label with the letter B on it, and stick it on top of the misleading G shown on the sign. And since I do not have permission to work in the area, I may well be arrested.

How to avoid the misery

One certain way to avoid "Heathrow misery" is not to fly to, from or through the airport. The airlines of the Gulf are doing their best to make sure that British travellers to Asia, Africa and Australasia can skip Heathrow. Etihad and Qatar Airways offer departures to their hubs from Gatwick and Manchester, both of which are preferable to Heathrow. And this month Emirates began daily flights from Newcastle to Dubai, adding to its UK network. Tyneside is now just one stop from Sydney and Shanghai.

Dubai airport has become a victim of its own success: on my last journey there, Terminal 1 (used by almost all British travellers) was full to the point where dozens of people were sitting on the floor. But a new terminal is set to open in March, which should instantly eliminate crowding. The first chief executive of Dubai Airports, Paul Griffiths, has plenty of experience of making life better for travellers. He served as Sir Richard Branson's right-hand man in developing Virgin Atlantic, then moved to Virgin Trains to oversee the introduction of new rolling stock. More recently, he was the boss of Gatwick airport, making it the civilised alternative to Heathrow. Mr Griffiths is now the highest-profile figure in the "brain drain" of aviation talent departing Britain for the Gulf.

Yesterday, Leo Seaton, the well-regarded communications manager for British Airways, spent his last day at the airline's Heathrow HQ. He has taken the Etihad dinar and will be making his way east to Abu Dhabi. Some people will go to any lengths to avoid Heathrow.