A confined space emergency plan is compulsory for confined space entry. A critical element of the emergency plan is the rescue / retrieval plan. The retrieval plan must be rehearsed to demonstrate that it is effective, that the plan and equipment selected is suitable for the space to be entered.
Many would-be rescuers have died after they discovered the self contained breathing apparatus they had selected could not fit through the manhole!
The standby person is responsible for initiating the emergency response, but must NOT enter the confined space to attempt a rescue / retrieval. Where other people are needed to assist with rescue / retrieval, they must be aware of the hazards and trained for confined space emergency response. Rescuers must be close by to respond in a "timely manner" (that is within minutes).
TIP - Where practical, ensure that two entrants are inside the space at any time. If there is a medical emergency (such as a heart attack) the second entrant may assist with the retrieval.