Which of the following is not a technical rescue?

High angle chain rescue is not classified as a technical rescue. Technical rescues involve specific skills and techniques to save individuals from hazardous situations that require specialized training and equipment, typically involving environments that are beyond the normal capabilities of standard rescue operations.

In contrast, high angle rescues are focused on situations where individuals are stranded or injured in areas requiring climbing gear and safety protocols for elevation. While these rescues are critical and require trained personnel, the term "chain" may imply a regular lifting or lowering process that does not necessitate the full array of technical rescue skills specifically associated with high angle challenges.

The other options clearly fit into established categories of technical rescues: confined space rescue involves saving individuals trapped in areas that are difficult to navigate, vehicle extrication pertains to removing individuals from vehicles after accidents, and trench rescue deals with situations where individuals are trapped in excavated areas. These three scenarios all require specialized training, equipment, and adherence to safety protocols specific to the nature of each environment.