Laura Kosakoski, a 34-year-old family doctor who lived in Canmore, Alta., died after she was buried in an avalanche in the Mount Hector area of Banff National Park on Jan. 10.

Her husband, Adam Campbell, was skiing with her that day. It took hours to locate her, dig her out and evacuate her.

He wrote an accident report about what happened that day in a Facebook post, in the hope of saving others from what he described as the horror he, family and friends, and first responders, endured.

You can read his account of that day and the lessons learned below.

My friend Kevin Hertjaas and I had been trying to coordinate schedules for a few months to ski together. We finally made plans to meet in Banff. My wife Laura joined us, too.

Kevin is a well-known and internationally respected ski guide with accreditation with the Association of Canadian Mountain Guides and the Canadian Avalanche Association.

Laura and I both have operation level avalanche certification and training and both logged more than 80 days of backcountry skiing in each of the past three years, with extensive experience before that, as well as a lot of summer mountaineering. I am also a member of the Avalanche Canada Foundation Board of Directors.

We were all very experienced and well trained.

Despite Kevin being a guide, this was not a guided day out. This was a recreational ski day for all of us.

There was new snow that week but temperatures were forecasted to be cold, around -15 C, and the avalanche conditions were considerable in the alpine and at treeline and moderate below treeline. There was a deep persistent layer in the snow that was reacting unpredictably that we all knew about.

We wanted a more casual day of powder skiing, with Kevin needing to get home early, so our options for where to ski were limited.

After a good discussion, we agreed to go and check out the Hector South area in Banff National Park along Highway 93 North. It's an area that has increased in popularity this past year but one that none of us had been to yet.

Experienced skiers, carried avalanche gear

After locating the likely access point in the trees from the highway, we pulled over and sorted our gear.

We had two inReach Minis with us, as well as a siltarp, a small emergency bivvy bag and full avalanche and cold weather gear.

With the equipment sorted, we began climbing the ridge through the trees around 9:30 a.m.

When we finally reached the treeline, we climbed a west-facing slope. As we climbed above the treeline, we noticed there was a solid windslab that had a drum-like feel so we opted to transition before committing to the bigger terrain above us.

We noticed a small slide path to skiers right of where we were. We identified there was a risk we would trigger a small wind pocket as we entered it.

The mountains don't care about your level of training, preparation, or how casual your days are. - Adam Campbell

Kevin went first and, as we suspected, he triggered a small pocket of snow that he was able to ski away from easily.

I followed a line more to the right of where he was, trying to avoid thin spots that were a concern. I skied without issue and then Laura joined us. We regrouped in a small cluster of trees and decided to go and look at a south aspect instead.

We climbed up through the trees to the ridge, happy that there was no obvious overhead risk. Once on the ridge, we traversed up to the high point. The wind was starting to pick up and visibility was limited. We transitioned from there and skied back along the ridge to a bowl/chute a little farther down to skiers left of where we were.

We saw no signs of any instabilities in the snow on that run. We did see big wind lips and wind loaded areas on skiers left of the lines.

Last lap of the day

Since there was a track in already, we decided to do one more lap before heading out. When we ascended back to the ridge, we noted that the wind had really picked up and it was cold.

We were happy to call it a day.

We stood at the top of the run, to ski right of the chute we had just skied. We identified a possible creek hazard below us, and spotted a nice access across the creek to exit onto the lower slopes.

We said we'd regroup at a cluster of trees at the bottom right of the path.

At 11:30 a.m., we gave Laura the honour of skiing first.

She skied right of the line, and then enjoyed great powder turns down the 400 metre (or so) line. When she was about two-thirds of the way down, Kevin dropped in a few metres left of her line and started skiing.

Wanting to keep my eyes on them, and wanting to watch Kevin ski for pointers, I moved forward onto the ridge crest.

The slope below me gave away

I was a further few meters left of Kevin's entrance and as I moved forward onto a possible entry point, the slope below me gave away.

I fell off the slab I was standing on that was starting to move at my feet.

I secured myself, yelled avalanche as loud as I could and watched the avalanche pick up speed and move the whole length of the slope.

I followed it, trying to see if I could spot Kevin and Laura until I saw a big powder cloud shoot through a small bench at the bottom into the creek.

I was trying incredibly hard not to panic. - Adam Campbell

I was shocked at the size of the slide.

Parks Canada Visitor Safety rated it a size 2.5 avalanche in an accident report posted two days later.

"The crown tapered dramatically along the crest of the ridge from nearly two metres in heavily wind-loaded drifts to as little as 40 centimetres. The avalanche ran approximately 550 metres. [It] ran on a weak layer of facets and depth hoar near the base of the snowpack. The avalanche caused most of the snow to be removed along its path, exposing the ground and scrubby trees in many places," the report read.

Once the powder cloud settled, I moved as far right as I could, to the other side of a small ridge, so that I wouldn't trigger anything else on top of Kevin and Laura below me.

I skied very cautiously down the line.

I could see Kevin below me, so I skied toward him. When I was approximately 50 meters above him, he told me that he saw Laura shuffling out of the way of the path into the trees and that prompted him to do the same which saved him from being caught in the slide.

We both yelled 'Laura'

He told me to start yelling her name.

We both yelled "Laura" approximately three times without a response. Kevin then instructed me to put my beacon into search mode and to get out my shovel and probe.

Being below me, he initiated the beacon search and was quickly drawn into the gully. The steep angle of the slope and the debris made doing the search complicated. As Kevin yelled out the reading on the beacon, the best reading we got was 3.8 meters.

We both knew instinctively that the situation was very serious.

Due to the depth and angle of the slope, we began digging at that reading.

We had to clear some snow before we could start probing. After removing over a metre of snow, Kevin probed and I deployed the SOS on my inReach at 11:45 a.m. When he finally got a probe strike, we started moving snow as quickly as we could.

With the angle of the the slope, we had to start tunnelling from almost 10 meters back of where the probe was to avoid more snow falling into the trench that we were digging.

45 minutes of digging to find her

As the time ticked away, I was trying incredibly hard not to panic and Kevin was doing everything he could to give me tasks to keep me focused. It took us almost 45 minutes, or more, to get to Laura. We were pulling out small broken branches, as well as very large and heavy slabs of snow, which slowed our digging.

When we finally got to Laura's head, there were no obvious sign of trauma but she was very blue and non-responsive. Kevin checked her airway, but there was no breath, although he told me there was one to keep me on track. Due to the position of her body, we could not perform CPR, so we had to keep digging to remove her from the hole.

Kevin left briefly to correspond with the Parks team via his inReach to state how serious the situation was. I continued to try and dig Laura out.

Kevin soon joined me and after a further 45 or so minutes of difficult digging we were finally able to free her.

Trying CPR, trying to keep her warm

We cut off her pack and hauled her out of our deep tunnel. Due to the steepness and depth, I would sit up slope of her and drag her up my body and across my chest as Kevin hoisted her legs from below. We had to do this about five times before she was clear of the entrance.

There were no obvious signs of serious trauma on her head or body but there was a deep laceration on her thigh, likely from a ski. I removed all the warm clothing I had in my pack and the bivvy bag.

Kevin started five rounds of CPR without any response.

We opted to stop CPR and put her in the bag with all our warm clothes to try and keep her as warm as we could.

We then prepared a possible landing area and waited for the Parks team to arrive by long-line.

I was trying not to panic and Kevin kept making up tasks for me to do.

Help arrives

When the team finally arrived, around 1:30 p.m., they packaged Laura out and then flew Kevin and me out by long-line and I collapsed into a screaming, crying mess.

We later found out that Laura's core temperature had dropped to 24 C and that she had no heartbeat.

She was flown to Foothills Medical Centre in Calgary where they slowly began trying to warm her core temperature and revive her. We do not know how long she was like that.

They were able to revive a faint heartbeat but she never regained consciousness. After receiving very professional care, she succumbed to internal injuries and was declared dead just after 6 p.m. on Jan. 11.

No light shines brighter. Because of your smile, you made life more beautiful ❤️ <a href="https://t.co/LB2xEBblMb">pic.twitter.com/LB2xEBblMb</a> —@campbelladam79

We were well trained, well equipped and despite it being our first day out together as a group, we had communicated well about our objectives, what we wanted from the day and our observations.

Despite that, we made mistakes that had fatal consequences.

What went wrong

We knew the forecast was for considerable danger but we were likely too complacent with that forecast and were not cautious enough.

We often ski in that rating, or higher, but we let our guard down.

We knew that any avalanche would likely trigger on a deep layer with serious consequence and that the layer was unpredictable.

There were also signs that we should have paid closer attention to.

We had earlier reactivity on a different aspect, there was obvious wind loading along the ridge and we underestimated the terrain's potential.

Given the avalanche bulletin for the day and our earlier observations, we should have skied safe zone to safe zone and not skied until the person was clearly in a safe area.

I likely moved forward onto a wind-loaded, convex roll (a slope that steepens as it descends) that triggered the slide.

I should have approached the line further right where there was less loading. I know this, but because I wasn't getting ready to ski into the line, I didn't think about it properly.

Based on where Kevin remembers last seeing Laura, it appears as though she was standing on the edge of the safe zone, but was not well placed in it.

I speculate that she was taking a photo because we never recovered her phone, so she may have not been as well protected as she could have been to take the pictures.

She was either knocked by the wind, debris, or part of the slide and pushed into the gulley below her, which compounded the effects of her burial.

It is also possible that the part of the trees that she was by were taken out because of the branches and deadfall we were digging out around her.

No good reason not to wear a helmet

Laura was not wearing a helmet that day, which was unusual for her. I do not know if this had any impact on her survival, but given that there were trees around, as well as the density of the blocks around her, it might help in a different situation or scenario. There isn't a good reason not to wear one.

Performing a beacon search in complex terrain is difficult. Digging and moving that much snow is incredibly hard.

Despite having done deep burial practices, being fit and motivated, it took a very long time to move that much snow. The tunnelling required to get to her was much more complex and difficult than I was ready for. It would be even more difficult if there was only one partner skiing — a factor to consider.

This was a worst-case scenario, on top of a worst-case scenario. Even if statistically low, the worst can happen.

It is a reminder that the mountains don't care about your level of training, preparation, or how casual your days are.

They are dangerous and demand full attention and respect and discretion is always warranted.