Definition
The highest elevation in the first 3,000 feet of the landing surface, measured in feet above mean sea level (MSL). It is published on instrument approach charts and airport diagrams for runways served by a straight-in instrument approach.
Plain English
It is the height above sea level of the part of the runway where the aircraft is expected to land. It tells the pilot how high that piece of pavement sits.
Context Anchor
Seen on instrument approach charts and airport diagrams or sketches when checking runway height information before an instrument approach or landing.
Derivation
Touchdown is where the wheels first meet the runway, the zone is the stretch of pavement where that should happen, and elevation is its height above sea level. The term names exactly what it measures.
Why Pilots Care
Used to set decision heights and minimum descent altitudes on instrument approaches and to confirm obstacle clearance.
Intuition Check
Do not read TDZE as the elevation of the whole airport, the runway threshold, or the exact spot where your wheels will touch. It is the highest surveyed point in the runway’s defined touchdown zone.
Example Sentence 1
The pilot briefed a TDZE of 412 feet for Runway 27 before beginning the ILS approach.
Example Sentence 2
Before the ILS approach the crew verified the touchdown zone elevation against the runway threshold height.