I don't know much about Halal, but Kosher definitely has very strict preparation and handling requirements, such that I believe (could be wrong!) that unless you special order a kosher meal, which will come to your seat sealed/wrapped, the regular catering is NOT kosher. They could offer "kosher-style" on the regular menu, which would mean no pork, no shellfish, no cheeseburgers (mixing dairy and meat), but that's usually fairly obvious from the description. The only nuance would be if a meat dish is prepared with butter, but I'm not sure that would even disqualify it as kosher-style (AFAIK there are not strict definitions about kosher-style).