Originally Posted by
Adlerdriver
Candler, doesn't the 747 have the same thing as a basic 777F with a main deck fire warning. Arm and activate the appropriate compartment switches and get a controlled depressurization? Obviously a rather cheap way to possibly buy some extra time at altitude if a suitable divert is not conveniently close by.
That's correct. The 747-400 has NO fire suppression on the main cargo deck. The controlled depressurization you mentioned brings the main cargo deck up to 25,000 ft, theoretically starving the fire of oxygen. The only problem is that when lithium batteries burn, they produce their own oxygen. In other words, if you have a runaway lithium battery fire on the main deck, you are in deep kimchee.
You've got about 15 minutes to get the plane on the deck somewhere/anywhere. Whether that's the ocean or some other piece of real estate, it doesn't matter, because you are going down one way or another.
At UPS, we practiced this 15 minute emergency landing scenario during past recurrent training. It's doable if you're basically right on top of an appropriate airfield, otherwise your options are limited to immediate ditching or an attempted landing in a "less than optimal" location. God help us all.