Any flare usage currently within ARMA 3 is useless.

The only ways a flare is useful at all, is if the flare if fired into the ground which then does illuminate the immediate surrounding area (ie. forest), or if the flare is used to signal an aircraft.

Could be when night ambient lighting was reduced to realistic levels, this also could have affected flare lighting as well as other secondary object ambient light source's ambient lighting levels such as flash lights. The developers might have been testing to see if the (more realistic) night ambient lighting levels was satisfactory before going through and adjusting all other light levels? Hopefully this gets fixed soon as the night ambient lighting levels are somewhat now satisfactory for the past months, and this secondary object ambient lighting level issue has been on going for quite sometime now!

Yes, this is annoying, glad there is a ticket for it.

Easy fix BI, get it done please.

Note that the illumination of each flare lasts all of about five seconds. The intensity of the flare also does not change as the flare dies. The flare suddenly stops emitting light when it should dim slowly over time. Flares should last at least thirty seconds. After about twenty-five to thirty seconds the flare should dim. After forty seconds the flare should no longer emit light.

I thought the flares did dim, but with a very short time span. Maybe the flares did so in previous versions? (Or maybe it was just wishful dreaming?)

ArmA3's Illumination rounds are too dark. it's very useless for oldstyle night combat.
in real life. illumination rounds are more brighter than ArmA3 (and even ArmA2!)
https://youtu.be/1sDraXd8cEc?t=3m35s

WORKAROUND: Use one of the BlastCore Explosion Effects mods/modules providing more realistic explosions as well as significantly increasing flare brightness to realistic levels as well as increasing chemical/glow stick brightness. (eg. extensions.) Most servers ban though any 3rd party mod, regardless of the 3rd party modifications intentions or usefulness. Server administrators are paranoid of hackers or are just lazy.

Anybody else realize that the AI have not utilized any flares or mortar flares as of yet within the games? (Except for aircraft chaff/flare counter measures.) But then again, AI probably have no need to use such devices due to their superior intelligence compared to the average player. A few smoke grenades are seen tossed every now and then these days, but likely no smoke grenades via rifle launchers or mortars either! AI should be far more aggressive with the players using these measures.