First thing first, I'm not an expert but I just want to add some point based on what Charmed said above. According to the rule set by IATA (International Air Transport Association), as long as the dog can do some basic movement within the crate like, lying down, moving around, sitting, etc, then I think it will be okay. For more accurate information, maybe you can visit the official IATA website.
One brand comes in my mind might be Ruff Max or Petmate. All in all, I think, instead of a crate, maybe you should consider the health risk for dog flying in the cargo too. I recently read an
article here by Dr Sara that you might need to take some precaution before flying in cargo.