The prop jet that crashed in North Carolina -- an Air Midwest commuter plane run by US Airways (UAWGQ) -- was part of an extensive industry system known as airline code-sharing.

Code-sharing, which literally means that one carrier shares its two- or three-letter ID code with another, began on the regional level. Major domestic airlines partnered with local or commuter carriers as a way of expanding their network of destinations and improving their convenience to attract passengers.

The practice has been so successful that nowadays major domestic carriers code-share with other major U.S. airlines and with international ones -- but often leave passengers in the dark as to which company's aircraft they will actually be taking.  

Read the Fine Print

Airline passenger and travel agent groups suggest that travelers read their ticket and itinerary information carefully so they know exactly what they're flying on all legs of their trip.

The Department of Transportation regulates that if a plane is being operated by a carrier other than the primary one, it has to be spelled out during the reservation process, generally either on the ticket or in the itinerary.

"People should always know what airline, what kind of aircraft," said David Stempler, president of the Air Travelers Association (ATA). "Many times, people don't know, don't care, don't look for it. But the information is there."

That's true whether a ticket is ordered online, through the airline or using a travel agent, he said.

But passengers who buy tickets on the Internet are often in a hurry.

"People who buy things online are not usually reading as carefully as travel agents," said Mike Greenwald, a spokesman for the American Society of Travel Agents. "They're getting themselves into trouble."

Greenwald says he frequently hears from fliers who ordered online and then have questions but don't know who to talk to. He suggests going through an agent or the airline to avoid that situation.

Passengers would be wise to look at their airline's Web site to see what carriers it partners with. All the major airlines list their partners online, according to Stempler.

In addition, they might be able to tell whether it's a regional carrier if the words "Regional," "Express" or "Commuter" are in the airline's name and if the aircraft is a smaller one.

Same Safety Standards

Until 1994, the safety of U.S. commuter airlines was a significant problem because many had lower standards than those of the majors, according to Stempler.

But the ATA and the Air Line Pilots Association succeeded in getting the rules changed so that the safety standards are now the same for all domestic carriers, regional and national.

"The safety of regional airlines has gotten extremely good over the last few years since the new rules," Stempler said.

Still, smaller or older planes generally aren't as safe as larger, newer ones – and often the crews aren't as experienced.

"We recommend to our members that the larger the aircraft, the better," said Stempler. "But sometimes you don't have that choice."

He said the type of prop jet that crashed, a Beechcraft 1900D, has a relatively good history and has been in service for a while.

Passengers should be particularly vigilant about domestic-international airline code-sharing, according to Stempler.

"The U.S. airline is supposed to check on safety standards of foreign carriers to make sure they're up to U.S. standards," he said. "But some (international) airlines have been removed from the relationship because of poor safety."

Travelers are advised to research the safety record of any airline or partnering carrier they're flying. Popular airline safety Web sites are: the Federal Aviation Administration's site, the World Aircraft Accident Summary and Airsafe.com.