# Relationship history for MSHA mine 1517157

Current hierarchy: **Skeens Stanley → Big Energy Coal Company → Big Energy Coal #6**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Hess Brothers Mining Inc → Big Energy Coal #6; 1991-11-01 to 1992-06-21; source msha-controller-operator-history
- **controller_controls_mine:** Hess Doug → Big Energy Coal #6; 1991-11-01 to 1992-06-21; source msha-controller-operator-history
- **controller_controls_operator:** Hess Doug → Hess Brothers Mining Inc; 1991-11-01 to 1992-06-21; source msha-controller-operator-history
- **operator_operates_mine:** Strong Fork Mining Inc → Big Energy Coal #6; 1992-06-22 to 1992-10-29; source msha-controller-operator-history
- **controller_controls_mine:** Powell Bob → Big Energy Coal #6; 1992-06-22 to 1992-10-29; source msha-controller-operator-history
- **controller_controls_operator:** Powell Bob → Strong Fork Mining Inc; 1992-06-22 to 1992-10-29; source msha-controller-operator-history
- **operator_operates_mine:** Big Energy Coal Company → Big Energy Coal #6; 1992-10-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Skeens Stanley → Big Energy Coal #6; 1992-10-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Skeens Stanley → Big Energy Coal Company; 1992-10-30 to current/open; source msha-controller-operator-history