board · load

1. Origins, structure, and basic meaning

• Structure: 搭 has 12 strokes and the on-reading とう. 搭乗 (とうじょう) concerns people boarding; 搭載 (とうさい) concerns carrying equipment or incorporating features.
• Basic usage: 搭乗 is used for passengers boarding. 搭載 is used for a vessel carrying a camera or a watch having a feature.

2. Common pitfalls and similar expressions

• Boarding procedures and installed features
  • 搭乗手続きを済ませた means completing the boarding procedure. Completing the procedure alone does not establish that the person has already boarded.
  • 機能が搭載されている means being equipped with a feature. カメラを搭載して describes carrying an installed camera, distinct from people boarding with 搭乗.