Definition
An ICAO air traffic control technique used in oceanic and remote airspace where ATC assigns each aircraft on the same route and flight level a specific Mach number to maintain. By holding their assigned Mach numbers, aircraft preserve longitudinal separation from one another without the controller needing continuous radar surveillance.
Plain English
A way of keeping airplanes safely spaced apart over the ocean by telling each one to fly at a specific speed and stick to it. As long as everyone holds the speed they were given, the gaps between aircraft stay roughly the same.
Context Anchor
Seen in international and high-altitude air traffic control procedures, especially where several jet aircraft are following the same general route.
Derivation
Named after Ernst Mach, the Austrian physicist whose name is used for the ratio of an aircraft's speed to the speed of sound. The 'technique' part simply refers to the procedural method ATC uses to apply it.
Why Pilots Care
Allows safe, orderly spacing for high-speed aircraft where pure distance-based separation becomes impractical.
Analogy
It is like several cars on a long highway being told to hold specific steady speeds so the gaps between them stay predictable.
Intuition Check
Do not read this as a pilot's personal flying technique. In this context, it is an air traffic control spacing method that uses assigned Mach numbers.
Example Sentence 1
After entering oceanic airspace, the crew was assigned Mach .82 under the Mach Technique and held that speed for the remainder of the crossing.
Example Sentence 2
Over the North Atlantic, pilots complied with the Mach Technique clearances issued for the entire flight.