# Relationship history for MSHA mine 2602179

Current hierarchy: **Lewis Tom → Hackett Environmental Systems Inc → Nlvat Plant (North Las Vegas Air Termina**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Hackett Environmental Systems Inc → Nlvat Plant (North Las Vegas Air Termina; 1991-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lewis Tom → Nlvat Plant (North Las Vegas Air Termina; 1991-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lewis Tom → Hackett Environmental Systems Inc; 1991-04-01 to current/open; source msha-controller-operator-history