I apologize in advance for the minutia thread - but it's long overdue.
I'd like to make an appeal to the long haul bros traveling with a roll of tin foil out there who fancy themselves as enroute gourmet chefs. To start, more power to you. Some heat applied expertly to a deli-tray can vastly improve it versus eating it cold. The guys bringing their own cookie dough and delivering freshly baked chocolate chip cookies to everyone earn beers for the trip duration in my book.

However - please stop wrapping the shelves in tin foil to create your culinary wonders. The ovens are convection ovens and require air circulation to function properly. There's a reason all the shelves have large holes in them. When someone offers to put a meal in and unknowingly puts it in with a foil wrapped shelf, it doesn't cook properly. It's getting old having to unfoil two or three shelves each flight.
So, cook away - make your crowd pleasers - just lay your foil on the shelf instead of wrapping it. Your cookies will actually cook better. Most importantly, no matter how you use the foil, get rid of it when you're finished. Thanks.

Tool box problems 😬

It’s not your fellow crew member wrapping the racks.

Do tell..... the tin foil bandits?

Don’t wrap it before you slide it in? That’s a new one.

When I was on the 777, it was maintenance. They do it so they don't have to clean the ovens. The bottom shelf covered in foil keeps food from dripping on the bottom of the oven.

Personally, I used to remove the foil every time I saw it.

Like the OP said, it's a convection oven. It does not work if the air cannot circulate. The holes exist to facilitate the air circulation.

I watched the catering crew in ANC take out each shelf and wrap it in tin foil. I told them it was a convection oven and he just made it harder to warm the food. I removed the tin foil as he watched.

I use a sharpened credit card, also useful for cutting LA catering tape, to make an X in the foil over the holes then fold the foil back. If my credit card needs sharpening I use my finger and poke the foil. I have also found that second generation Tempe Mission Palms pen will do the trick in a pinch.

Not really. Simply no standardization being followed.

Before you point the finger at your fellow crew member you should do more research.

Something as simple as aluminum foil at This corporation tends to be made complicated.

You are correct on that these are convection ovens and their operation, however the manufacturer stated the ovens were built to cook a lot more meals than one or two as we do. Their recommendation was not to have all the racks covered in foil and that weather it had one or two meals in the oven they would be fine. That was for the MD11 and the triple.

There was/is a fix to this and there is a procedure for the cleaners and other departments to follow.

We took a delay on my last long haul flight because our over failed (I always check before flight). Maintenance showed up and they first thing they did was to take out the tray lined with aluminum foil. Per maintenance, the foil restricts airflow and the oven throws a code and shuts down. The had to replace the over anyways (took three folks to change them).

This was the THIRD airplane in less than 3 months where the over was broken. At least on the last flight we caught it before flight. A 13-14 hour flight with no ability to heat up your food really sucks.