You are a manager of tourism agency, what would do if someone from the oldest people in your staff made a mistake that costs you 10k USD ?

Everybody is bound to make mistakes, there are ways to tackle the situation by every manager when mistakes are made.

Firstly we need to analysis what is the cause of mistake. i.e. in what circumstances in which the decision was made which went wrong due to which company had to bear such a huge loss.

It is not mandatory that if mistake is been committed by new staff he should be punished and if the same mistake is made by old staff, it should be ignore. Old or new status doesn't make differences when a mistake is committed.

Everyone who makes a mistake has to be punished, only that the punishment will vary to the extant of damage caused due to mistake. i.e. if the mistake which resulted in few USD losses, company can give warning to the staff only, whereas if the mistake has costed huge losses, the punishment can be as serious as sacking a person.

As a manager I will try to retain staff as much as possible wherein I know he is an effective staff and I can gain much much more higher value in future. I would warn him or may be suspend (without pay) for sometime so that he can understand the nature of loss.    

If one person has made one mistake that has cost a lot of money, then you have to look at your processes and procedures - it is likely that they are not sufficiently robust.  Over a long period of time, every mistake that can happen will happen.  For small mistakes that isn't a serious problem, but for big mistakes it is, and in general it should be impossible for one mistake to cost a fortune - it should require at least two mistakes, and preferably more.   It is necessary to change your system since the existing one has failed.

The next issue is management.  Was the person who made the mistake adequately trained, equipped and supervised?   There may or may not be a fault in the management.

Finally we come to the individual who made the mistake.  It is common practice for a person in this situation to be temporarily suspended on full pay on a no-fault basis while the situation is investigated.  In other words they are sent home on the clear understanding (i.e. clear to them, the management and the other staff) that this nothing to do with blame or fault, it's just so that the investigation can be done fairly.  Obviously they will be a very important part of the investigation.

During this time it is usual for the management to consider whether the person is otherwise a good employee or a poor one.  In other words, is this somebody that you want to keep or not?

Finally you can come to a view as to what happened.  The person may be effectively innocent or partly or wholly to blame.  Only once a full understanding of the circumstances has been obtained can you decided what to do.  The reaction of the person to the event may be taken into account.

Deductions from salary are not appropriate in a case of this kind, and in any event are likely to be unlawful.  You may end up firing the person.  If you do, think carefully about how you handle it and what you will say if asked for a reference.  Anybody can make a mistake and the person has already lost their job: there is no need to damage their future or career any further than is necessary.