Which Words Should Start With Capitals? ....

[The Builder]

Discussion in the pub last night.

Which words in this sentence should begin with a capital letter ...........

"The commanding officer asked the flying officer if he had seen the commander."

Not a trick question. The chap would really like to know, but there were varying opinions.

[dannyk13]

None of them IMO

[dannyk13]

Second thoughts Flying Officer.

[Stephen_G]

Commanding Officer - Flying Officer - Commander

[Prudie]

I'd agree with Stephen although I'd say it was based on tradition rather than a grammatical rule. Only proper names should be capitalised nouns but those are ranks that are frequently abbreviated to their initials in capitals eg CO for Commanding Officer.

[Stephen_G]

Most of that was my thinking, Prudie.

[dannyk13]

commanding officer and commander are not ranks in the context of the above sentence.

[chrissa1]

Yes. Proper names should have capitals.

[MargoTester]

None in this sentence . However capital should be used if referring to a named person ie Commanding Officer Brown etc.

[chrissa1]

Yes, alen but, "the flying officer came into the room" could mean he came in, flying through the air, which he obviously, didn't.

[chaptazbru2]

Ditto Stephen G.

[Old_Geezer]

How do you know ? Were you there ?

[chrissa1]

The CO asked the FO if he had seen the, C.

[Quizmonster]

Flying Officer is a specific rank in the RAF, so it will invariably be capitalised. The same is true of Commander, a specific rank in the Royal Navy, though the word 'commander' itself might apply to the leading officer in any military unit. The same applies to the phrase, 'Commanding Officer'. Since your example sentence has the word, 'the' before each of these, it is clear that a specific person is being referred to in each case, so it would seem reasonable to capitalise all of them.

[SirOracle]

You have all forgotten "The". ;-)

[Hypognosis]

Commanding officer… of what? It doesn't say. Open to the imagination, perhaps?

Other than that, if not a recognisable rank, "commanding" is just an adjective (lwr case), officer is just a noun (lwr case).

Wing Commander is a real rank.
Commodore is a real (naval) rank.

"Commander", by itself, isn't recogniseable but I'm just a bar-prop, as far as this field of interest goes.

Acronyms are capitalised, by convention. They just look like bad typos, otherwise.

[Quizmonster]

I hadn't Sir Oracle, but we did cross-post!

[Prudie]

Now I see why the Builder ended up in a discussion :-)
The Commanding Officer is one person not any old person who throws his weight around. You wouldn't see "the general was awarded the OBE". Like I said I think it's not a rule just common usage that includes some observation of respect.
Flying Officer (RAF) and Commander (Navy, Police) are both ranks. CO is not.

[Prudie]

Hypo I have to disagree, all Army bases for example have one person who is overall in charge, they may be a Colonel, Lt Colonel or much higher but they would all be referred to as The CO. CO is a specific single person.

[jno]

"The".

Titles get capitals, jobs don't, so "Flying Officer Briggs" but "the flying officer". (But it's all a matter of taste, there are no laws.)