SMOKE SCREEN: A 777 makes its final approach to Kathmandu airport on Sunday, flying over a brick kiln stack which makes visibility worse.

Monday afternoon at TIA. The seven parking slots at the international apron are full. The two gates that can take heavy jets are both occupied by 777s of Korean Air and Thai. A Gulf Air 767 that was diverted to Dhaka because of poor visibility has just flown in and has nowhere to park. Last week it was worse: planes had to wait for up to 45 minutes after landing before passengers could disembark.

The domestic terminal looks like the deck of an aircraft carrier; the only thing missing is the catapult. With random parking and unauthorised ground vehicles moving about it is a miracle there aren't more collisions. Inside the international terminal it's bedlam. Passengers waiting since morning are packed like sardines into two cramped departure halls. The line for men at the security check stretches all the way back to immigration because only two of the four x-ray machines work. Though there are only two women at the female security check, no one is taking the decision to shorten the male queue.

Two trekkers are being grilled after security and their sunblock rudely confiscated. The frisker does a "wallet check" on an unsuspecting passenger and helps himself to a $20 note from a passenger who decides against making a fuss. Bhutanis on the Druk Air flight are singled out for special extortion and harassment.

In the dingy arrival hall, tourists who arrived without visas have now waited for more than one-and-a-half hours in various queues. Even Nepalis have to wait to get back into their country because there is only one counter for them, and they grumble darkly.

Downstairs at baggage claim there is utter chaos and no one knows which flight's luggage is on which carousel. Some passengers who arrived on the Nepal Airlines RA 416 flight from Kuala Lumpur at 11AM are still waiting for their baggage-there has been an epidemic of theft in the luggage handling area.

Outside, hundreds of people who have come to receive passengers throng the gate. The flight information screen doesn't work. Clueless people ask clueless policemen on duty about flight status. Tourists are swarmed by touts, and those who opt for pre-paid taxis are bundled into 30-year-old Datsuns that belong in museums.

This is the situation on any normal day at Tribhuban International Airport in Kathmandu. Things are much more chaotic when the weather is worse and flights get cancelled as they did this week with Delhi out of action, or the airport is gheraoed by burning tyres on the Ring Road, ensuring that no one can get into town.

But if there is chaos on the ground, things are getting untenable in the air. Kathmandu's airport has been overrun by urban sprawl and now sits in the middle of a crowded city. At this time of year, Kathmandu Valley's pollution and winter inversion close the airport until past noon on most days. Big jets need at least 2,000m visibility, but winter fog has been made even worse by brick kilns on the approach path in Lalitpur. On 18 December, a jet with 250 passengers on board that was running low on fuel finally landed on its fifth attempt. Early morning flights from Dubai, Bahrain, and Doha often circle for three hours before diverting to Delhi or Dhaka.

Even domestic flights returning from Lukla or from mountain flights have to make expensive detours for instrument landing from the south due to poor visibility. "This is a very challenging airport, but these days it has become much worse because of smog," said one international airline pilot who regularly flies into Kathmandu.

Nepali pilots have written to the Civil Aviation Authority demanding urgent attention to everything from deficient navigation aid and poor transmission quality of air traffic control, to ground and air congestion. Says one pilot: "I guess the airport just reflects the general state of the country."