Long queues are a constant feature of many airports
Flying into India's financial capital Mumbai (Bombay), air passengers are transported over some of the largest slums in Asia, before landing at the country's biggest international airport.
In some places, shanties are built perilously close to the edge of the airport's main runway.
"Slums have encroached on 200 acres of airport land," Mumbai airport director Sudhir Kumar told the BBC News website.
An attempt to demolish the slums earlier this year was hurriedly shelved after a political outcry, because the government had done little to rehabilitate the inhabitants.
It has meant that plans to expand Mumbai airport have been put on hold, until a solution to the problem can be found.
'Where is the space?'
Across India, airports - many of them built by the British during WW2 - are overstretched as the country goes through an aviation boom.
Air traffic across India has grown by 30% in the past eight months after the government changed the country's aviation policy, allowing more airlines to begin operations.
At the start of the year, India had five airlines operating scheduled services within the country.
By the end of the year, another five are expected to have begun operations.
International flights have also increased after recent decisions to modify existing agreements governing the number of flights between India and countries such as the United States, Britain and France.
By the winter of 2006, there will be 56 flights a week between London's Heathrow airport and Mumbai and Delhi.
Recently, the Singapore government asked India to consider increasing the number of flights between the two countries from the current 53 per week to 212.
"Where is the space?" one senior airport official asked in private, throwing up his hands in despair.
"Delhi airport's single runway handles 25 aircraft movements every hour - the [civil aviation] ministry want it to be increased to 32.
Work is on to upgrade existing airports
"How can we do that if we cannot build a second runway?"
The main problem is finding the money to upgrade India's creaky airport infrastructure.
"We have calculated that in the next few years, something like 400bn rupees ($9.2bn) needs to be invested in Indian airports," India's civil aviation secretary, Ajay Prasad, said in a recent interview.
But the government insists that help is at hand.
They have decided to invite private consortiums to jointly develop Mumbai and Delhi airports, with private companies which will hold a majority stake and manage the airports.
Bids for the process have been invited and several international companies including Aeroports de Paris, Frankfurt Airport, Airports Company of South Africa and Flughafen Munchen Germany have expressed an interest in the venture.
Two completely new airports are also being built in the southern infotech cities of Bangalore and Hyderabad.
Both airports are being constructed entirely by private companies.
Bangalore international airport is being developed by a consortium led by Germany's Siemens group, at a cost of 14.1bn rupees ($325.6mn) while a similar amount is being spent on the Hyderabad airport by the GMR Vasavi group and Malaysian Airport Holding.
Both airports are expected to be completed by 2008.
Work is also going ahead to expand and develop some of the country's smaller airports.
Amritsar airport, in the northern state of Punjab, was a sleepy airport a few years ago with a single flight a day operating out of a terminal in a tin shed.
It now has 56 flights a week.
Most of them cater to the massive ethnic Punjabi community living in the UK and North America.
On Saturday, Air India begins a direct flight linking Amritsar to Birmingham and Toronto.
"It's aimed at Punjabis travelling home and helping them avoid having to fly to Delhi and then drive up to Punjab," Air India Director (PR) Jitendra Bhargava told the BBC News website.
Amritsar is one of many smaller airports being upgraded, with 790m rupees ($18.2m) being spent on a brand new terminal which is expected to be ready by October.
But with the rapid increase in the number of flights, most air travellers are getting impatient.
Mumbai airport is surrounded by slums
"India's airports are a joke," says Sarabjit Singh, a Delhi businessman, as he joins the lengthy queue at an airline check-in desk.
"For a country that constantly compares itself to China, we don't have an airport that matches even the most basic international standards - no clean toilets, decent and affordable restaurants, internet cafes or duty free shops," he adds.
Anita Prasad, who travels frequently between Delhi and Hong Kong, concurs.
"You should see this place after midnight [when most international flights leave].
"There is a queue to get into the terminal, another one to screen your bags, a third in front of the check in counters, then one to get your passport stamped, of course another one in front of security check and then there's the one at the gate to board your aircraft.
"I absolutely dread travelling by air."