I am still looking for the hot entrees, but have not been able to figure out how to have a fresh and hot Dinner and Breakfast entree with the current crew on board. Having a hot entree brought to the train before departure, then kept hot in convection ovens will not work, the entree will taste bad, especially the breakfast being served 18 hours or so after boxed. So if you can not add more personnel, what are the options other than cold boxes? Contemporary and Fresh is the Theme, no labor used on board the mandate, satisfied customers the goal. I know my way around the commercial kitchen, but this is really difficult. The only real solution is for Congress to reverse the F&B mandate.
You keep the hot entrees chilled until it is time to heat them. Then you move the entrees in foil packets out of the refrigerator and into the convection oven and turn it on.
I doubt that the hot entrees served toward the end of long-haul flights are kept warm the whole time. Instead, they are kept cold (loaded frozen?) and then reheated at the appropriate time in a convection oven. I figure on an aircraft the entrees are delivered on some sort of rack and stored in the oven itself until it is time to turn it on.
In case it has been a while since you were last on a long-haul flight with complimentary meal service, the flight attendants go down the aisles with a cart. Some levels of the cart have the meal trays with the sides and dessert already on them. Each passenger is asked which entree they want (if there is an option), and the associated foil packeted entree is added to the meal tray. If a SCA has a similar cart, it would make serving hot meals only slightly more complicated (on the upper level, at least) than an all-cold option. But flight attendants usually don't have to carry meals up or down stairs to serve them. A SCA would need to do so.