The are two 18 Charlies per A team. They employ conventional and unconventional warfare tactics in combat engineering and maintain team engineer equipment and supplies. The engineers are able to destroy as well as build just about any structure. He is a key player in any civic action mission. Each engineer sergeant is able to train, advise, or lead indigenous combat forces up to company size.

The engineer sergeant is responsible for performing sabotage operations, training indigenous personnel in engineer skills, and supervising combat engineering functions when conduction split-detachment operations and missions.

Each 18 Charlie must first go through the Special Forces Assessment and Selection (SFAS) where they have to swim in boots and BDUs, run an obstacle course, and take long treks with a loaded rucksack. During this time they are assessed on their ability to work as a team member. Upon selection they then enter the Special Forces Qualification Course (SFQC or "Q Course").

SFQC is divided into three phases, The Individual Skill Phase, The MOS Qualification Phase, and The Collective Training Phase. The first phase lasts 40 days and includes land navigation, patrolling, and an obstacle course. In the qualification phase, which lasts 24 weeks, they learn construction, field fortification, and the use of explosive demolitions. They are also taught improvised munitions, domestic and foreign landmines, countermine operations, bridging, rigging, electrical wiring, reconnaissance, and target analysis. The third phase lasts 38 days and consists of Special Forces doctrine and organization, unconventional warfare operations, direct action operations, airborne and airmobile operations, and methods of instruction.