The sappers are called because the suspect the hikers are under the snow where zina is .
Idea to engage sappers for searching the remaning bodies was questionable from the very beginning. It was clear that the hikers had left the tent in a hurry, and they had not managed to take big metallic things that could be spotted by sappers' detectors. Why not to add more dogs instead of sappers? Zina's body was found by a dog. so that method proved to be effective. How effective the suppers were, they showed when they failed to find Rustem's body, which was not that far from the spot where Zina had been found.
When it is highlighted that most of the equipment is still on the tent, they then get the sappers to use poles
Again, not effective. Sappers are professionals trained to use detectors. Searching with poles is low qualified job, which can be easily done by students and Ivdellag soldiers. Anyway, Senior Lieutenant Avenburg would have been enough to manage the group of sappers, involvement of Lieutenant Colonel Shestopalov was redundant. And if we recall that 5 more high ranking officers arrived to Ivdel together with Shestopalov, we can suppose that searching the bodies was not their only task in Ivdel.
It is slightly confusing but we can look at the logic of the the unfolding event's. The UPI were slow in starting the search , there was also confusion of another hiking group being late to return from their hike but they turned up . Once this is understood, the organisation of a search gets underway. There is another delay as the search organisers aren't fully aware of Dyatovs route.Dyatlov and the UPI didn't seem to follow procedures for this and it was another friend or student that came forward with Dyatlovs intended route as I think dyatlov had discussed this with him.
So the search parties are organised to be dropped at various stages around the whole 200km loop in the hope of finding them alive . ( There is no need for metal detectors at this point because they don't if they are alive or dead).
Those search parties dropped off from the 21st on the ground are looking for the hikers or their trails . The searchers are made up of many people and back grounds, those that are fit and have mountain experience or knowledge of the area are chosen because of this. Resources of the military are also used and is a standard procedure , not all military staff are frontline.
When the tent is found they call all the other search parties to that area at 1079. Plans are made for a base camp and there will be engineering duties needing done in parallel with having a go with a metal detector. I would think the sappers are not just utilised for their metal detector. There will be digging, landing pad , campsite , looking to be done that may need a bit of engineering knowledge.
So the dogs and sappers are requested after they know some bodies are buried and the early suspicion is that the hikers are all in the creek bed or ravine where ZIna and Igor were found . That is a logical assumption given what they discovered on the first days. They know that the snow depth is up to two meters deep in places in that creek and that's what the drawing with red hash marks is about and the search area.
There would be no need for more dogs or sappers because both are limited in deep snow. This is why the probs were used and more probes were requested. The probing was hard work and all people were used in those tasks because of the harsh conditions and lack of manpower.
It was a probe that found rustem ,so the dog missed him too. They even requested a sound echo device that they thought existed by word of mouth. It turned out that there was no such thing.
Sappers are trained in many things, building bridges , digging holes , engineering projects , dams etc etc. the are man power that is needed and probing the snow is neither low or high qualified job, it is a necessity when searching and is done by many qualified people when they search.
I think Shestopalov was reported to have been wondering about probing randomly.
If they were looking for bits of rocket , I think the others there would have seen the activity, there wasn't anywhere to hide on the slope , at the helicopter site or base camp. ?