The original Aviator flashlight was a plastic and alloy number by Just Rite that was a 2x AA with a #222 bulb that had a thumb operated "tit" that slid a red lens over or away from the bulb tip. Like other military lights of that era the switch was part of a pocket clip where sliding a ball forward caused parts to make contact. Pulling back caused parts to separate. There were some blue but those reportedly never were issued.
By Vietnam Just Rite made them of alluminum and the less than reliable switch was now a twisty at the rear instead. Reportedly some green were also issued. The thinking there was if a pilot were shot down behind enemy lines green would light their way while being harder to spot by the enemy. No yellow lens was needed as the bulb tint already was.
Both have a red lens.
It was those funky purple Mickey Mouse ear beamed SureFire'd LED's that needed yellow/green to mimic incan at that time.
We all know SureFire did a great Aviator light no doubt, but I just wanted to say where the idea for green began.