The world is full of different airlines ranging from ones with proven track records of safety and security to ones with old, poorly-maintained planes that are falling apart. Are there any resources for travelers to help determine which airlines are widely considered safe to fly?
I often just look up the Wikipedia article for the airline.
So for example, when in the 'stans earlier this year, I was considering airlines like Kyrgyzstan Aircompany - which as soon as you start reading the article, you'll find it's on the list of airlines banned from flying over the EU...., which quickly made up my mind about it. Although they were cheap...
The list of these airlines is a rather handy one, as it comes down to banning them due to not being up to scratch safety-wise, or for known poor levels of maintenance.
Whenever I fly with a dodgy airline like for example this summer with aerosvit, I check first this page. It doesn't look very sexy, but it really helps to get an overview about how other flyers have rated the airline.
You don't really get a safety report, but if a lot of traveller complain about the dirty and old looking plane, I suppose that the airline isn't the best and safest you can get.
If you're more the numbers guy, you could check this website that lists all airplane accidents. There is also a section that lists those accidents by airline. So you have an objective way to measure the safety of an airline.
Another interesting statistic you can find here. It lists the accidents per aircraft type. So you can assess the safety of an aircraft independent of the airline it is used by. One the same site you find also a statistic sorted by airlines.
This site is an useful resource if you want to dig deeper into the topic of air safety.
Last but not least, I want to add a fact that I read a lot but I'm not sure if it is true. But a lot of sources state that Qantas from Australia is the only airline with no fatal accidents in their whole history. So maybe the award of the safest airline should go to Qantas.
For Safety, a good starting point could be the List of Airlines that are banned in the European Union. Airlines that are allowed in the EU can be considered quite safe.
Quality is a bit hard to measure, since everyone has different standards on this. On http://seatguru.com/ you can compare airlines and even their specific aircraft. It will show you seating schemas of the planes and even state width and depth of the seats.
Reliability is usually not too much of an issue. Long distance flights are mostly on time, but any airline can have severe delays from time to time. Since they need to pay everyone a lot of money if they are too late, they will try really hard to avoid that.
If the airline is in the IOSA registry then you can be sure it's safe.
If the airline is allowed to fly in EU/USA/Canada/Australia/New Zealand then it's safe.
Beyond these two, it's practically anyone's guess. Perhaps the airline is perfectly safe but the IATA Operational Safety Audit is awfully expensive and they didn't want to pay for it. There are airlines (notoriously Air Koryo) which is in the IOSA registry but not allowed into the EU. What to make of that... I do not know.