It takes several assembly lines in "flight kitchens" serving major airports to put together tray upon tray of meals, pack them in those skinny service carts and then make each meal is in the right cart for the right cabin and in the right place to be picked up for the right airline and flight on which the meal is featured and rotated that day. Cold foods such as salads and desserts in one line, hot items such as meats and vegetables in another, soups and sauces somewhere else with cutlery and glassware in still another. Special meals have their own preparation areas while, depending on the size of the market, kosher and halal will have their own sections!
Beverages, spirits and enough ice packed in dry ice so it won't melt is the neatest trick to make sure there is enough to handle a 15-18 hour flight because there is no 7-11 at 41,000 feet! Finally, keeping all those logo embossed dishes with unique designs straight adds to the fun as well - soup dishes on Lufthansa or bento boxes on Japan Airlines?
Portion control is the key to "packing" an airline meal. It ensures consistent servings for every customer and absolutely determines the cost of each meal which can range from as little as $8.00 per person in coach to over $200 a piece at the front of the bus where caviar, champagne, steaks and Maine lobster dishes created by the hottest chefs on the planet are the order of the day.
Airlines will sometimes share on their websites what meals are being served on which month and in which direction. It might be apple-glazed chicken on every British Airways flight from London to New York with almond-roasted ahi in the other direction - each and every day for all of October. Most customers don't fly the route every day of the month but they definitely don't want the same meal in both directions. Come November that meal pairing might switch over to the Chicago or South Africa route and so on and so on but there's more. It also has to match the printed menus as well as the manifests printed out for the flight attendants who need to know what to expect and how to heat it all up. Among other things now you have an idea what all that banging around in the galley is for while you're boarding the plane and finding your seat: meals counted and correct!
Logistics and organization are critical at every kitchen but airports like Baltimore with hardly half a dozen international flights a day have it easier than operations like London where nearly every major flag on the planet stops in at least once a week. Airlines also regularly inspect the kitchens to ensure food quality, refrigeration and sanitation requirements are met. Individual travelers have their own opinions about the quantity and quality of the food but everyone agrees that it at least has to be fresh and from as clean a kitchen as possible.