What pilots mean when they say "heavy"
Wake turbulence categories, why they exist, and why a 747 has to announce itself on every radio call.
Listen to any approach frequency and you will hear it: "Speedbird nine-two heavy, descend flight level one hundred." The word is not swagger. It is a safety instruction.
Why the word exists
Every aircraft in flight trails two counter-rotating vortices from its wingtips. They are invisible, they sink, and they persist for minutes. A large aircraft generates vortices strong enough to roll a smaller one past the limit of its aileron authority - which is exactly what has happened, fatally, more than once.
Air traffic control therefore separates aircraft by how much wake they make, not by how big they look. The pilot appending "heavy" to the callsign is telling every controller and every other aircraft on frequency how much room to leave behind.
The categories
| Category | Maximum take-off mass | Typical types |
|---|---|---|
| Light | up to 7 t | Small piston and turboprop aircraft |
| Medium | 7 t - 136 t | Airbus A320 family, Boeing 737 |
| Heavy | above 136 t | Airbus A330, Boeing 747, Boeing 777 |
| Super | - | Airbus A380, Antonov An-225 |
"Super" was added for the A380, whose wake was measured as substantially stronger than anything in the Heavy category. It is a category with almost no members.
Why it matters on a tag
The HEAVY edition takes its name from this. Those pieces are cut from overlapping fuselage panels - the doubled sections where two skin panels meet - which makes them roughly three times the thickness of a standard piece. The name is borrowed, but the weight in the hand is real.