Hundreds of Vietnam combat helicopter pilots, their families and Gold Star families planted a tree in Arlington National Cemetery on Friday to commemorate the 50th anniversary of the first U.S. combat troops entering the Vietnam War.

The group called it the largest gathering of pilots, with 1,000 expected, says Bob Hesselbein, president of the Vietnam Helicopter Pilot Association, which is holding a five-day meeting in Washington that ends on Saturday.

Hesselbein says he met with the family of 1st Lt. Carlos Pedrosa and talked about a picture he took of him in 1972 at Kon Tum Airfield, the day before his death.

"Between missions I found Carlos among our dispersed aircraft and had him quickly pose for a individual picture," says Hesselbein. "Our aircraft were dispersed to reduce the risk of many being hurt during the frequent rocket attacks we endured while operating from the airfield. As bad luck had it, the very next day Carlos was killed instantly by a 122mm rocket that struck him in the area visible in the background of the previous day's portrait."

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