Definition
Airports designated by the FAA as having such heavy traffic volume that the number of IFR operations (takeoffs and landings) is limited by rule during specified hours. Reservations or slots are required to operate at these airports during the controlled periods. The current designated high-density airports are listed in 14 CFR Part 93.
Plain English
Airports so busy that the FAA caps how many flights can take off or land per hour. Pilots must reserve a time slot to fly in or out during the busy hours.
Context Anchor
Seen in discussions of standardized taxi routes, especially at busy airports where pilots follow assigned ground paths between runways, ramps, and gates.
Derivation
"High-density" comes from "density" (Latin densus, meaning thick or crowded). In this context it refers to a high concentration of aircraft operations packed into a limited time window — not the density of the air itself.
Why Pilots Care
Following the designated routes prevents confusion, improves flow, and lowers the chance of incidents during peak operations.
Analogy
Think of a busy airport like a crowded road system during rush hour. Marked routes and clear instructions matter more because many people are trying to move at once.
Intuition Check
Do not read “high-density” as meaning physically heavy or tightly built. Here it means operationally busy: many aircraft movements in the same airport environment.
Example Sentence 1
Because JFK is a high-density airport, the crew obtained an arrival slot before filing the IFR flight plan.
Example Sentence 2
Standardized taxi routes are published mainly for high-density airports to reduce the risk of pilots taking a wrong turn on the ramp.