Mumbai's new airport faces traffic woes as it takes on Singapore and Dubai

The airport is spread across over 1,100 hectares and will eventually have four terminals carrying 90 million passengers every year

For a first-time visitor, landing in India's financial capital Mumbai can be quite an experience.

At approach, as the flight cuts across the Arabian Sea and flies past the mangrove marshes, the great metropolis emerges - swarming with railway tracks, towering skyscrapers and the dense habitation of Asia's largest shantytown pressed tightly against the airport's periphery wall.

For years, aviation experts have flagged the dangers and inefficiencies of operating an overworked airport right in the middle of such an urban setting, with buildings obstructing the flight path and safety and operational constraints preventing pilots from using the intersecting runways at once.

But a long overdue alternative is finally on the horizon.

After numerous delays and impediments, the Navi Mumbai International Airport (NMIA) is set for inauguration soon and expected to get operational in the coming months.

The airport will "significantly ease congestion" in India's financial capital, Arun Bansal, the CEO of Adani Airport Holdings Limited, the operating company, told the BBC.

"The current airport has hit its capacity of 55 million passengers annually. There's already demand for an additional 20 million and we are set to meet that at Navi Mumbai," said Mr Bansal.

While numerous connectivity, integration and policy related hurdles still need to be ironed out, the airport's opening will turn a significant new chapter in India's aviation ambitions.

The current airport has hit its peak capacity of handling 55 million passengers annually

Spread over 1,100 hectares and located some 40km (24 miles) from the old commercial centre of Mumbai, the sprawling new airport is connected to the island city by India's longest sea-bridge. It has two parallel runways and will eventually handle 90 million passengers per year, following subsequent phases of expansion.

"NMIA will make Mumbai the first large Indian city to operate two airports - a demonstration of the growing importance of India as an aviation market with rapidly increasing passenger and air traffic," said Shukor Yusof of Singapore-based Enadu Analytics.

The sector has seen double-digit growth in the last four years - outpacing most other regions in the world. Indian airlines have placed orders for some 1,900 new aircraft, a thousand of which are expected to be delivered in the next five years, making such infrastructure critically important to accommodate this new fleet.

Adani says NMIA will be India's first fully digital airport that's been "designed and developed specifically to become a hub airport" with advanced technology for check-in, security, baggage and boarding drastically reducing turnaround times and facilitating easy transfers.

It has already announced a partnership with India's largest and newest carriers, Indigo and Akasa Airlines, who are launching new routes. And Air India has committed to flying to 15 cities from the airport, gradually scaling up operations, including flights to international destinations.

Given how starved Mumbai's current airport is for capacity, analysts expect strong uptake for NMIA's parking slots from airlines looking to launch new routes.

But major challenges are expected as operations commence in the coming months.

NMIA will operate two parallel runways

Given how far the airport is, its location could be a significant inconvenience to passengers - both when taking flights to and from NMIA, and especially when using it for connecting flights.

It can easily take between two and three hours to reach the airport from certain suburbs of Mumbai.

A direct 20-minute metro line between the old and the new airports is likely to become a reality only after a few years. In the interim, NMIA is planning to provide electric buses at regular intervals for passengers with connections.

"This is not ideal," says Alok Anand, a Bengaluru city-based aviation consultant, but it is typical of many projects in India where supporting infrastructure follows, rather than being built in tandem.

"Until last mile connectivity is fixed, I don't foresee anyone landing at one airport and travelling to the other to catch another flight," Mr Anand says.

It's probably why, for now, both the existing and the new airport will handle domestic and international traffic, even though in the longer run, when connectivity improves, overseas flights may exclusively fly from NMIA.

A direct metro line between the old and the new airports is expected to become functional only after a few years

Connectivity and regulatory issues could also become impediments to NMIA's ambitions to make Mumbai an international hub like Singapore or Dubai - where flights come from various destinations and connect passengers to onward routes around the world.

While NMIA, along with a few other airports in cities like Hyderabad and Bengaluru, are technologically advanced and compete with some of the best in the world, India still needs to revise its policies to facilitate smoother transfers, which is key to succeeding as a hub, say experts.

"For instance, to transfer from domestic to international terminals or vice versa, one needs to undergo security screening again, which is not required at most major global airports," says Ajay Awtaney, editor of LiveFromALounge, an online aviation and hospitality portal.

"Additionally, we need to reassess our security practices to improve the efficiency of passenger throughput. Our contact frisking at the airport takes significantly more time than other airports, which have transitioned to body scanners," Mr Awtaney adds.

Mr Bansal agrees that a lot of this will need to fall in place before Mumbai's aviation profile is raised to global standards.

A change in regulation, he says, will also need to be accompanied by airlines' willingness to expand their choice of long-haul destinations. Carriers will also have to optimise their fleet strategy and connections to be able to leverage the city's strategic location advantage between Europe, the US and Asia.

For now, NMIA solves the city's immediate problem - acute air traffic congestion.

It will also serve as a larger catchment area, which could extend all the way to the neighbouring Pune city, a major IT and education hub.

"Some of the major cities around the globe, such as New York, London, Dubai, and Tokyo, all operate with two to three airports. Mumbai will join this select club," says Mr Awtaney.

And so will Delhi, where a third airport - Jewar - is all set to open in the coming months, to serve the capital's satellite areas.

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