Everest Base Camp seen from Crampon Point, the entrance into the Khumbu icefall below Mount Everest, after an avalanche that killed 16 Nepalese sherpas. (Robert Kay/AFP/Getty Images)

Discovery Channel’s Mount Everest special tracking veteran climber Joby Ogwyn ended in the worst possible way last month; as the crew was prepping to start the journey, the deadliest avalanche in the mountain’s history killed 16 Sherpa guides. The network scrapped the live special, produced by NBC News, and will now air a documentary called “Everest Avalanche Tragedy” on Sunday night.

Three of the deceased guides were going to be on Ogwyn’s climbing team. Ogwyn was at Everest base camp at the time, as a camera crew was about to film his quest to attempt a wing suit flight off the summit of Everest, the highest peak in the world.

In a phone interview this week, an exhausted-sounding Ogwyn explained that he was in his tent about 6:45 a.m. the day of the disaster when he heard something extremely loud outside. He went to investigate and witnessed the harrowing site of the avalanche coming down, burying people in the Khumbu Icefall (one of the most treacherous parts of the mountain).

Joby Ogywn (Discovery Channel) Joby Ogywn (Discovery Channel)

Estimating that he was about a half-mile from the avalanche, he immediately found his climbing partner and tried to communicate with his Sherpa guide team. When he couldn’t get in touch with them via radio, he dreaded the worst. Tragically, the guides were right in the middle of the avalanche.

The Discovery/NBC News team switched gears into recovery mode. Ogwyn and his team tried to help, though there wasn’t much they could do in terms of a rescue – many who got hit were killed almost instantly. But Ogwyn, his climbing partner and a cameraman traveled to the icefall, bringing supplies to survivors and helping get everyone else off the mountain. They also helped the search that was underway to find the bodies of his Sherpa team.

In the emotional days following, they had to decide what to do about their own climb up the mountain with the Discovery project. “We took some days because we really didn’t know what the aftermath would be,” Ogwyn said. They waited for the Sherpa guides’ decision; though some Sherpas were still up for the trip, others didn’t want to go. Eventually, the whole community decided not to climb. (A week later, the Nepal side of the mountain closed for the entire season.)

Now, Discovery’s new documentary at 9 p.m. on Sunday will look at the weeks leading to the climb through the moment the avalanche struck the Khumbu Icefall, along with real time footage; plus, an interview with Ogwyn, expedition leader Garrett Madison and additional members of the expedition and production teams. The network is also donating to the American Himalayan Foundation Sherpa Family Fund, which helps the families of the deceased.

Ogwyn is still badly shaken from the experience. “Hardest job in the world to go rescue your dead buddies off that mountain and that’s exactly what everybody came together to do that that day,” Ogwyn said in a Reuters video afterwards. “So it’s a really powerful story and it needs to be told. I don’t know if I’ll ever be able to watch it. My heart’s broken and I’ll never, ever get over it.”

Nepalese from youth groups participate in a candlelight vigil in memory of those killed in the recent avalanche at Mount Everest. (Bikash Dware/Reuters)