Which city, Seattle or Los Angeles, is closer to the southeast Asian city of Manila in the Philippines?

Believe it or not, the world is not flat, which makes the standard printed map of the world deceptive. Following the curve of our round planet, Seattle is nearly 650 miles closer to Manila.

For airlines and their passengers, that 10 percent difference matters.

This geographic factor combined with the growing world fleet of ultra-long-distance, yet smaller jets -- Boeing's 787 Dreamliner and Airbus' A350 -- means there is a real possibility of airlines opening new nonstop routes to Asia out of Seattle-Tacoma International Airport.

Kazue Ishiwata, senior manager of air service development at Sea-Tac, mentions Manila, Ho Chi Minh City in Vietnam, Bangkok in Thailand, the enormous secondary cities of inland China -- such as Chengdu or Nanjing -- and even Indian cities including Delhi, Hyderabad and Mumbai.

"Southeast Asia was difficult in the past because of aircraft range. It becomes viable with the 787 and A350. We are the closest gateway to those cities," said Ishiwata. "We are positioned to serve those cities well in the future. We are looking at all of these."

"We have possibilities for secondary cities in China that we are very interested in," she added.

Ishiwata said the airport is currently talking to a number of airlines about potential new nonstop routes to Asia, though she declined to identify them for competitive reasons. The first of these "could be happening anytime soon," she said.

New Opportunities

To understand the geographic element in airline planning, consider another striking example.

If you live in Seattle and want to fly to Singapore, there's no nonstop flight. But in June, United plans to open a new ultralong, nonstop service on a 787 from San Francisco. So you could fly there first, a two-hour flight, to catch United's 16-hour trans-Pacific flight.

Yet thanks to our northern latitude and the curvature of the earth, Singapore is 700 miles closer to Seattle than L.A. and nearly 400 miles closer than San Francisco.

And because airlines prefer their jets to hug the coastline where possible rather than fly over vast stretches of open ocean, the difference is even larger when considering the actual routes flown.

That United flight out of San Francisco will fly back up the West Coast in an arc over Seattle on its way to Singapore.

This is a key reason why Delta chose to open an international hub in Seattle.

A new report on the future of trans-Pacific services just published by OAG, a consulting company that gathers and analyzes air travel data, concludes that the 787 and A350 will "bring new opportunities to Seattle."

Sea-Tac airport "is typically closer to Asia than Los Angeles by 1,000km (621 miles) or more which gives it a unique advantage for potential nonstop services to places such as Kuala Lumpur, Jakarta and Chennai," the report states.

Those cities are specified because all lie within the unrestricted range of a 787 from Seattle, but are just out of range from L.A.

Ishiwata said none of those are likely to open up soon as new routes from Seattle because distance is only one factor. For an airline, the viability of flying between two cities depends on being able to connect travelers at both ends of the route.

That's why Amsterdam and Dubai are two highly successful international routes out of Sea-Tac.

Emirates is now flying twice a day from Seattle, though few of its passengers are ending their journey in Dubai. About half of the passengers on the Dubai flights are headed to or from India, many of them local tech workers and their families.

Dubai's geographic advantage, offering a central hub between Europe, Asia and Africa, means Emirates can connect its Seattle passengers to every major Indian city.

An airline theoretically could now open a nonstop route from Seattle to an Indian city such as Hyderabad, a popular destination from Seattle because that's where Microsoft has its largest IT operation outside Redmond.

But making that route viable would require partnerships with Indian airlines that could offer frequent connections to many other Indian cities. And the challenge of competition from those two daily Emirates flights would make it a high-risk venture.

Today, Seattle has nonstop service to just six destinations in Asia, all of them very large coastal cities: Beijing, Hong Kong, Seoul, Shanghai, Taipei and Tokyo.

But just as geography has influenced the growth of Dubai's hub, so Seattle may in future exploit its own trans-Pacific advantage to develop new routes to secondary Asian cities further south or inland.

The smaller size of the 787 and the A350 will help.

Larger jets such as the 777 and the 747 have the range to reach those cities, but for an airline developing a new route, those planes are too big.

An airline can fill a 240-seat 787-8 on a new route a lot more easily than a 365-seat 777-300ER. And the 787 is also more fuel efficient than the larger jets.

Ishiwata said flying a shorter distance nonstop, besides offering passenger convenience, reduces the biggest cost for an airline operating a long-haul international service: fuel.

"An airline can spend around US$30 million a year on one route on fuel alone," said Ishiwata. "If you save 7 to 10 percent of that per year, that could make it or break it. It's a big deal to have a shorter distance."