The deadly crash of a TransAsia plane into a river in Taiwan is again focusing the world's attention on the safety challenges facing fast-growing Asian airlines.

TransAsia has been adding new routes rapidly since the Taiwanese carrier went public in 2011. TransAsia and others like it are rushing to keep up with a travel boom driven by the region's growing middle class.

The ease and increasing affordability of flying helps fuel economic growth and a better lifestyle for Asian consumers. But as airlines carry more passengers across increasingly crowded skies, they are also racing to train enough pilots.

"The demand is almost exceeding the supply," says John M. Cox, who spent 25 years flying for US Airways and is now CEO of consultancy Safety Operating Systems.

Quickly-growing airlines need to maintain standards as they hire more pilots, maintenance workers, dispatchers and flight attendants. Cox says the Asian carriers are currently meeting those marks, but it's a big challenge.

TransAsia Airways Flight 235 crashed Wednesday shortly after takeoff from Taipei, Taiwan, with 58 people aboard. Dramatic video from a car's dashboard camera captured the moment that the plane, tilting madly, clipped a bridge before landing in a shallow river. At least 26 people were killed.

It was the second fatal accident in just over six months for the airline and its seventh serious accident in the past two decades, according aerospace publication Flightglobal. It comes barely a month after an AirAsia plane crashed into the Java Sea in a flight from Surabaya, Indonesia, to Singapore, killing all 162 aboard.

As Southeast Asia's economies grow, more people have money to travel and airlines are adding planes to whisk them across the region.

Aircraft manufactures Airbus, ATR, Boeing, Bombardier and Embraer delivered a whopping 1,543 new planes to airlines last year. That means a total of 30 planes rolled off their collective assembly lines every week -- the fastest production rate in the history of commercial aviation.

Most of those aircraft went to Asia.

TransAsia Airways, Taiwan's third-biggest airline, has been part of that buying spree. The airline was founded in 1951 but has undergone a growth spurt following its market debut on the Taiwan stock exchange in 2011. It has added about two dozen routes to mainland China and other Asian cities. TransAsia flies about 20 planes from its base at Taipei's Sungshan Airport and has enough new aircraft orders to double its fleet within five years.

"The Asian carriers are trying to really expand quickly," says Michael Barr, an aviation-safety instructor at the University of Southern California. "When you've got cockpit seats needing to be filled, you're going to fill them."

Barr said that compared with a generation or two ago, new pilots don't get as much flying training. More of the training is done with on-the-ground computers and simulators because it's cheaper.

The turboprop plane that crashed Wednesday was less than a year old, according to Ascend, an aviation consultancy. It is an ATR 72-600, made by a joint venture of Airbus Group and Italy's Alenia Aermacchi. The aircraft was powered by two Pratt & Whitney PW100-127M engines. TransAsia also flies Airbus jets on some short-haul routes around Asia.

The airline's most serious crash occurred last July, when 48 people were killed after another turboprop plane crashed on an island off mainland China during stormy weather.

There are currently 1,600 aircraft operating in Southeast Asia, Brendan Sobie, analyst at the CAPA Centre for Aviation, a consultancy in Sydney, told The Associated Press in December. He said Asia is the only region of the world where there are as many aircraft on order as already in service, "so the growth seems set to continue."

For each new plane, airlines need to hire and train at least 10 to 12 pilots, sometimes more, according to industry experts. The figure is so high because planes often fly throughout the day and night, seven days a week, while pilots need sleep and days off.

Right now, Asia-Pacific accounts for 31 percent of global air passenger traffic, according to the industry's trade group, the International Air Transport Association. Within two decades, that figure is forecast to jump to 42 percent, as Asia adds an extra 1.8 billion annual passengers for an overall market size of 2.9 billion.

Boeing projects that the Asia-Pacific region will need 216,000 new pilots in the next 20 years, the most of any region in the world, accounting for 40 percent of the global pilot demand.

To put that in perspective, there are about 104,000 pilots working in the United States, flying everything from crop dusters to jumbo jets, according to the Bureau of Labor Statistics.

"The exponential growth in and the demand for air travel were not anticipated by many of the governments in the region," Shukor Yusof, founder of the Malaysia-based aviation research firm Endau Analytics said in December. "And so you're seeing a lack of infrastructure, airports and pilots because nobody expected low-cost travel would have taken off as quickly, as rapidly, and would be as lucrative as it is now."

The U.S. has many pilot-training facilities, from universities to specialized flying schools. And it has a farm system of regional carriers that train and churn out experienced pilots for the largest airlines. But Asia, home to fast-growing carriers such as AirAsia, Indonesia's Lion Air and India's Jet Airways, doesn't have enough training programs for all the pilots it needs, said David Greenberg, a former Delta Air Lines executive who also oversaw pilot training and safety at Korean Air.

The result, Greenberg said, has been pilot poaching -- carriers in the Middle East and Asia have recruited in the U.S., Canada, Australia and Europe to fill their cockpits.

Greenberg said that while he was at Korean Air, 10 percent of the carrier's captains were foreigners who came from 28 different countries.

Meanwhile, many pilots, engineers and technicians in Southeast Asia have been lured to more attractive jobs in the Middle East, which boast higher salaries and the opportunity to fly in sleek new aircraft.

Money -- or lack thereof -- is at the heart of much of the region's staffing shortages, says Lim Chee Meng, CEO of Mil-Com Aerospace Group, a Singapore-based aviation training company that provides training for many of the region's airlines. Wages for pilots and technicians in Southeast Asia have not risen fast enough to compensate for the cost of training. That discourages people from wanting to pursue an aviation career in the first place.

The shortage of trained staff means there are fewer workers to juggle an ever-growing workload -- and that comes with risks.

Still, the aviation industry has generally done an amazing job of improving safety while doubling the number of passengers in the past 15 years.

In 2013, 3.1 billion passengers flew globally  twice the total of 1999. Yet the chances of dying in a plane crash were much lower.

Since 2000, there were less than three fatalities per 10 million passengers, according to an Associated Press analysis of crash data provided by  consultancy Ascend. In the 1990s, there were nearly eight; during the 1980s there were 11; and the 1970s had 26 deaths per 10 million passengers.

That is not to say some parts of the world aren't more dangerous than others. The accident rate in Africa, for instance, is nearly five times that of the worldwide average, according to the International Civil Aviation Organization, part of the United Nations.