Just on Saturday we shipped a cooler of 250lbs of fresh salmon and halibut back from Van Island by air by vac packing it and icing it right down for the drive from Port Hardy to Sidney Airport. Once near Sidney, we ditched the ice and layered in 9 bags of frozen peas (they don't leak and are cheaper than ice packs). The cooler sat on the tarmac in 33 degree heat for 3.5 hours and then it was in transit for another 5 hours until we got it home. The fish was ice cold and the peas hadn't completely defrosted. The key is to get your meat as cold as possible before shipping and it will last close to 24 hours without any appreciable change in temp. If frozen, wrapping each package in a layer of newspaper is effectivie in giving you a few extra hours.