leaving his baby, phoenix and luna, in the back of a hot car. his family called it a horrible accident. >> they're completely crushed by this incident. >> reporter: at least 24 children have died in hot cars on this year. on average it happens every nine days. that's why advocates are pushing the hot cars act requiring all new cars to be equipped with a safety alert system to detect the presence of a child. the hope, an added safety net for parents with many wondering why it keeps happening. >> when we're under stress or fatigued or there's a change in a routine, very easily our brains can go into auto pilot. >> reporter: jenny stanley is backing the bill. her 6-year-old daughter sidney died in 2010 after climbing inside a hot car when her parents weren't looking and getting trapped. >> what's the most difficult part for you to remember from that day? >> it was just a horrible accident but there's so much guilt. >> reporter: now hoping a new law can help save a life. blaine alexander, nbc