"fire a flare" is correct and usable in written English.
You can use it when you are speaking about sending up a signal into the sky to attract attention, for example, "He was stranded on the island for days before finally firing a flare to alert passing ships."
But someone did manage to fire a flare, setting in motion a remarkable rescue effort on Sunday by fishermen and pleasure boats that prevented an even greater tragedy.
"Today, I'm here with a mindset that I would fire a flare to kick-start a new history of peace, prosperity and better inter-Korean ties," Kim said in his opening remarks to Moon.
You're never too far from an extraction point, so once loaded you head to the nearest one and fire a flare into the sky immediately altering everyone else around you to your position, and letting them know that a chopper's on its way.
You're never too far from an extraction point, so once loaded you head to the nearest one and fire a flare into the sky – immediately altering everyone else around you to your position, and letting them know that a chopper's on its way.
You will want to fire a flare if you see a passing ship or plane.
The rescuers said one of the crew fired a flare she found in the water.
He fired a flare gun, and the pirates, thinking they were being fired upon, responded by shooting him.
Elsewhere, fishermen armed with gaffs and sticks sank another Zodiac and, according to Greenpeace's Knowles, fired a flare at the observation helicopter.
An initial Pentagon statement said one of the American escort planes had fired a flare to warn the Iranian jet away but later retracted that report.
Foster was also found guilty of the minor charge of unsafe storage of weapons, and another defendant was found guilty of firing a flare gun.
