badger said:
1, if its a group you do not know you call out if not back at time X
2, within our group if not back at time X we go and check where parked and cave entrance then call out
although probably would agree should call out at time X, better to have a false alarm be embarrassed and have to buy the beer for the rest of the night
Assuming that the person(s) who have the callout time in front of them are competent cavers and in the region, there is of course a middle path, which is to do exactly what Badger describes, make a preliminary reconaissance. That could either be just to the entrance, or possibly underground as well, depending on the cave system and circumstances.
You don't have to ring Cave Rescue at the first sign of trouble if you have the competence to deal with an underground energency yourself, with the obvious caveat that if you are truly competent you should know when a situation is too difficult to handle on your own.
So...I wouldn't have been waiting for 1h40m. I would have gone looking for them (having given someone else a revised deadline for making a full call-out).
Obviously it depends on the cave. For example if a party was missing in Lost Johns, it takes only 10-15 minutes to get to the top of Dome or Centipede. If there is still no sign of them, then things don't look so good. Ideally I would be with more than one person and at that stage I would send someone out to raise a full call-out, while continuing on down myself (with basic emergency equipment, e.g. food, survival blankets, first aid kit etc.). On the other hand if a party is lost in Easegill or Daren Cilau, making any kind of quick search is very difficult.
In summary, I regard a call-out time as the time I have to do something. What I do is down to my judgement, it won't be a reflex action to pick up the phone and call cave rescue.
Even if you do ring the cave rescue, be prepared to have a discussion with the duty controller. You can then describe the situation, what cave, how many people, how experienced, when did they go underground, when were they expected back etc. The duty controller can then use his/her judgement and local knowledge to decide what to do. The controllers are pretty sensible people. A quite likely outcome is that they will send just a small team to do exactly the kind of reconnaissance I describe. They main advantage is that they will have comminucations equipment, which means thay can escalate the rescue faster if needed. So don't think if you call the rescue that you are necessarily going to incovenience dozens of people.
Obviously the situation is very different in other countries. Here in Sweden there has to be much more emphasis on self-reliance simply because the caves are in very remote places. It would take hours to respond to a rescue call-out and the total number of people that can be called out is not very large.
Hmmm. An important subject.
Mark