American, United, Delta. Yeah, yeah, we can debate, but they're peas in a pod. But if you find a cheap fare on Allegiant, or Porter, or Fly540, what are you supposed to think?

Smaller airlines come and go. Back in 2005, I wrote an article about flying on smaller airlines -- of the 13 companies mentioned, three have gone out of business and one now only flies charters. Meanwhile, new airlines keep cropping up, like Porter in Canada and VivaAerobus in Mexico. With an airline industry permanently in flux, don't worry if you've never heard an airline's name before -- rather, check it out. Here are some tools and tips for giving an airline the once-over.

Check the Blacklists

The U.S. and EU governments both keep lists of airlines they consider unsafe. The U.S. government actually blacklists entire countries (Read the U.S. blacklist here) based on assessments of the countries' airline-safety standards. The agency offers the results as an Excel spreadsheet with the unsafe nations listed as category 2. Right now, that includes Belize, Congo, Gambia, Ghana, Haiti, Honduras, Indonesia, Israel, Kiribati, Mexico, Nauru, Nicaragua, Paraguay, Philippines, Serbia, Swaziland, Ukraine, Uruguay, and Zimbabwe. Carriers from those countries aren't allowed to set up new service to the U.S. until they improve safety standards, although they can maintain existing service.

The EU keeps a blacklist of individual airlines, which you can find at Air-Valid.co.uk (www.air-valid.co.uk/airlines-blacklisted.html). These specific airlines aren't allowed to operate in the EU, so you can pretty much assume they're not the best of the global array. The vast majority of the airlines are smaller African and Asian airlines, but there are a few more prominent players on there such as Iran Air and Philippine Airlines.

Ignore the Boards

Don't turn to boards like TripAdvisor or our own forums for good advice on airlines. People on forums tend to draw wild conclusions from single events -- saying, for instance, that you should never fly United Airlines because of one incident involving a rude flight attendant or a poorly-handled cancellation. Every airline has made mistakes, and you need to take a longer view.

How About Awards?

Skytrax (www.airlinequality.com), Zagat (www.zagat.com/promo.aspx?pn=132), Conde Nast (www.concierge.com/tools/travelawards/readerschoice/transportation) and JD Power and Associates (www.jdpower.com/travel/ratings/airline-ratings) all take that longer view. Of the bunch, Skytrax (a UK-based consultant to airlines) has by far the widest range of airlines listed, rating them from one to five stars and giving them sub-ratings based on everything from food quality to "assisting parents with children." Skytrax's set of hundreds of traveler reviews is also a great exception to the "don't pay attention to forums" rule, as their reviews are mostly from experienced road warriors.

According to Skytrax, the finest airlines in the world are Asiana, Cathay Pacific, Kingfisher, Malaysia, Qatar and Singapore. Among the lowest-rated airlines is one very popular European one -- Ryanair -- chosen in large part because of its famously, abysmally poor customer service.

Hedge Bets With Alliances

The major U.S. airlines are members of three alliances: OneWorld (www.oneworld.com), SkyTeam (www.skyteam.com) and Star Alliance (www.staralliance.com). If you're flying on a foreign airline that makes you a little nervous -- say, Aeroflot -- see if you can get a seat on that flight using its American partner's code (in this case, Delta's), which makes the American partner partly responsible for getting you to your destination. For more on that trick, see my article "How to Decode Code Shares."

Scope Out Safety

If your airline hasn't won any awards, but it isn't on any blacklists, you might want to scope out the airline's safety record. For more than a decade now, AirSafe.com (www.airsafe.com/airline.htm) has been tracking air crashes and other safety-related incidents. They can tell you the rate of fatal events per million flights, and when the airline had its most recent incident.

You have to be smart about this data. Midwest Airlines, for instance, appears to have a high fatal accident rate -- but that's just because of one accident back in 1985. That said, a combination of a high fatal-event rate plus recent fatal events might give you pause.

Make Note of Fees

Smaller airlines, especially low-cost ones, may have different baggage allowances or fees than larger carriers. If you're assembling a multi-airline itinerary, pay attention to those fees. The most notorious culprit is Europe's Ryanair, which has very low base fares but also very low allowed baggage weights. It doesn't make sense to book an itinerary which would force you to re-pack your baggage when you change planes.

Compare Seats

If you're trying to decide between two airlines which are "just fine," you can easily see which one has comfier seats, better food and in-flight entertainment. Seatguru (www.seatguru.com) gives you seating charts and details of in-flight entertainment for many popular airlines and aircraft. (To figure out what kind of plane you'll be on, see my earlier story, "Secrets of Airline Seating.")

The rather messy, French-run website Air-valid.co.uk has information on seat pitch and in-flight entertainment for more international carriers as well as a sort of comparison engine that gives you a bit more information.

Sascha Segan has been writing for Frommer's since 2001, authoring the books Fly Safe, Fly Smart and Priceline.com for Dummies and collecting Lowell Thomas awards from the Society of American Travel Writers Foundation for his Frommers.com columns in 2007 and 2009. He's also the managing editor for mobile at PCMag.com. He lives in Queens, NY with his wife and daughter, who frequently accompany him on his trips.

Do you have more tips for checking out an airline? Share them in the comments below or join in our Air Travel Forum.