Well, on fire fighting aboard ship... Something of an expert here.
First, it depends on what kind of fire it is.
Burning solid "stuff" that produces ash like wood, paper, cloth, etc., can potentially survive a cycling of the air lock / depressurization and reflash when the atmosphere is returned. You need to thoroughly cool off such a fire and watch the area for several hours afterwards.
Burning liquids could be extinguished by venting, but coating the liquid with a fire retardant like foam is far better. Dry chemical will also put it out quickly.
In both cases, but particularly liquids, smoke is a huge danger. Venting would work, but you couldn't depressurize and retain the atmosphere as it would be heavily contaminated by the fire's gasses and smoke.
Electrical fires only last until the power goes off. They stink horribly but aren't much of a threat unless they ignite other "stuff." The usual is a big flash, a loud bang, and the "fire" is over. Oh, the smoke on these is extremely toxic usually. You gag and cough horribly if you get a snoot full unlike what happens with the amateur fireworks shown on sci fi movies when control panels "explode."
Then there's special cases... You have something that has it's own oxidant in it. Vent that and you do nothing. The fire continues because it doesn't need outside oxygen.
If enough heat is present, venting and restoring the atmosphere only delays ignition, not eliminates it. Heat transfer in a vacuum isn't going to be quick either. Radiation is not nearly as effective at removing heat as convection or conduction are.
Venting is also not going to be a realistic option if the compartment isn't directly accessible to space. If you have to vent the fire through a number of other compartments to space expect every one of them to suffer damage to some extent. You can't use the ventilation system as a route as outlined below.
Another problem is, potentially, venting other compartments to get the compartment with the fire vented may cause additional casualties (damage) to the ship or crew. What if there are crew in some of those compartments who don't have pressure or vac suits? What if there's equipment or supplies that will be damaged or rendered useless if exposed to a vacuum?
Another real danger on a ship is the fire can spread. It could ignite insulation on wiring, or the heat on a bulkhead ignites paint or other materials on the far side. Now you have two compartments on fire. It loves to travel through ventilation ducting. You have a 30 year old ship that's never had the ducts cleaned properly? That fire is going to ignite all the Eeeewww in those vent ducts and once it does, that fire goes everywhere that duct goes.
Or, you've had things painted 10 times, and there's three layers of vinyl tile on the decks. That just makes it easer for the fire to ignite the far side of bulkheads and decks.
Then there's training. Most civilian ships don't have crews that are particularly well trained in emergencies like this.
http://shipdetective.com/advice/safety/fires.htm
The usual result is a "Chinese fire drill" with lots of panic and little effective action.
Since
Traveller doesn't list a particular skill for this sort of thing (say, damage control, or firefighting), there really isn't a mechanism in the game to know how well a character would be able to deal with such an event.
If you've never been in such a situation it goes for the uninvolved something like this:
There is an alarm, announcement, etc., of a fire aboard the ship. You begin to secure hatches and such to prevent it spreading.
The next thing you notice is the smell of smoke. It permeates
everything and even a small fire can be smelt at quite a distance.
You get
zero information on what's happening. For all you know the rest of the ship had burned to the waterline.
It takes forever for the fire to be declared out and things to return to "normal."
You feel panic you keep fighting down. That's for those who've never been there done that.
If you're uninitiated or trained in firefighting, when you see a sizable fire where it shouldn't be, the first two reactions are usually panic followed by flight or confusion.
Automatic fire fighting systems work with variable results. They are also more expensive up front to install and require regular maintenance. So, you install the system and forget about it for 10 years... It doesn't work when you need it. Surprise!
Overkill on extinguishing is also possible. This results in damage to stuff that wasn't damaged by the fire or other secondary problems.
That's my 2 cents on shipboard firefighting.
