Even after repeated deployments to Iraq and Afghanistan, Maj. Robert Marshall, an Air Force Special Operations pilot from Mercer Island, has rarely been content to stay at home.

Instead, he has hungered to climb mountains.

On Monday, Marshall was one of four active-duty airmen to summit Mount Everest.

The ascent was the final climb in the USAF 7 Summits Challenge, co-founded by Marshall in 2005, which has sent Air Force climbing teams to the top of the highest peaks on every continent to honor fallen comrades and raise money for military charities. Marshall climbed six of the peaks, forced to retreat from Mount McKinley when he was called back from leave because of an upcoming deployment.

Once on top of Everest, he took off his oxygen mask to repeat a ritual begun on earlier peaks he had summited.

“I dropped down and did 30 push-ups,” Marshall said in a satellite-phone interview Wednesday evening (Pacific time). “Everyone else on the summit was giving me a strange look, like ‘What’s this guy on?’ ’’

The 7 Summits Challenge is independent of the Air Force, with the climbers taking leave to participate in the climbs. But the Everest expedition has drawn plenty of interest from within the Air Force for what team members say is the first active-duty U.S. military team to summit the mountain.

In a May 16 note posted on the challenge’s blog, Air Force Chief of Staff Gen. Mark Welsh wished the team good luck on the push to the summit.

At Schriever Air Force Base in Colorado, crew commanders in the 2nd Space Operations Squadron banded together to cover the shifts of an Everest team member, Capt. Colin Merrin, on the Global Positioning Satellite Operations floor.

“We all simply could not be more proud of Capt. Merrin and the USAF 7 Summits Challenge for reaching their goals at the top of the world,” said Lt. Col. Thomas Ste. Marie, in a written statement.

Six climbers were on the Air Force team, with Merrin and a second airman turning back before the summit. They were part of a larger group of climbers and Sherpas who reached the summit with International Mountain Guides of Ashford, Pierce County.

“The ambient air temperature was probably about 20 below (Fahrenheit) but there was a very light wind so they were actually good conditions,” said Eric Simonson, a partner with International Mountain Guides.

They reached the summit just a few weeks after the 50th anniversary of the ascent by Washington climber Jim Whittaker, the first American to reach the top of Everest.

Today, hundreds undertake the grueling climb required to reach the top.

Marshall endured many long hours of climbing, with his weight plummeting from 157 pounds to 140 pounds. But he said one of the biggest challenges on the final ascent was making his way past slower climbers, some who did not have adequate gear.

“We had to make a risk-management decision to stay with them and waste oxygen and time, or unclip (from a rope) and kick steps around them in the ice and snow. We had to do that about five or six times,” said Marshall in an interview Wednesday from a village at the 12,000-foot elevation, far below the mountain’s summit of more than 29,000 feet.

Marshall, 34, is now based in Amarillo, Texas, where he is a test pilot for the V-22 Osprey.

Growing up in Washington, he hiked and climbed in the Cascades. He earned the nickname “The Goat” while scrambling up 14,000-foot peaks when he attended the Air Force Academy in Colorado Springs, Colo.

Marshall conceived of the climbing challenge in 2005, while based in England, as a way to highlight the spirit and camaraderie he found in the Air Force.

A few months after its launch, several of his friends died in a plane crash in Albania, and then two more died in another crash. He and challenge co-founder Maj. Mark Uberuaga decided the climbs should honor the memories of his dead colleagues and help raise funds for charities that support families of survivors.

Over the years, team members have paid for their own expenses to climb the mountains. They also raised more than $75,000 for nonprofits that help members of the service — Special Operations Warriors Foundation and That Others May Live Foundation — according to Marshall. Some donations paid for two airmen who had been wounded to travel this spring to the base camp, he said.

The team began the climb in late March, and hopes to be in Nepal’s capital of Katmandu later this week.

Hal Bernton: 206-464-2581 or hbernton@seattletimes.com