Originally Posted by
deltahotel
Most pure freighters don’t have fire suppression on the main deck. They do have fire detection in the form of smoke detectors, so in the absence of these there would need to be some form of fire watch personnel.
The other big issue without a cargo door is loading/unloading times as everything has to go in via a normal pax door.
There is some more discussion of this in R&N about 737 freighters and, I think, a picture of a 777 with all the seats/overheads stripped out.
Pure freighters deal with a main deck fire by depressurizing and staying at altitude (FL250 in the checklists that I have flown). You can not do that with passengers in the mix.