Definition
HEIGHT ABOVE TOUCHDOWN (HAT)
The height of the Decision Height or Minimum Descent Altitude above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway). HAT is published on instrument approach charts in conjunction with all straight‐in minimums.
- See: DECISION HEIGHT
- See: MINIMUM DESCENT ALTITUDE
Source: FAA Pilot/Controller Glossary (verbatim from the Federal Aviation Regulations).