Firefighter is more accurate than fireMAN- again it may be either sex.

Flagger is better than FlagMAN, right?

As Kevin says, wrong. Man means person, not male. Chairperson, personhole cover, & so on, are ludicrous pieces of PC garbage that only show up the PC brigade's ignorance of their own bloody language.

Wife originates in the AS wifeman. Wife being pronounced wee-fa; & cognate with the modern weaver; the person that weaves. As opposed to (if I remember Kathleen Herbert's lecture correctly) wepman, the man (i.e. person) that carries weapons. In AS, the origin of the bulk of modern English, man means person & needs to be qualified before it denotes gender. In Modern E. it may mean male when used alone, but still tends to be neuter as a compound noun & this is why you will hear references to e.g. "Madame Chairman". A "fireman" is exactly that - a PERSON that fights fires.