What does Heavy mean in an ATC callsign? Learn which aircraft use it, why wake separation changes, and how to use the suffix in flight sims.
In real-world aviation and flight simulation, “Heavy” after an ATC callsign identifies an aircraft in the heavy wake-turbulence category, normally one with a maximum certificated take-off mass of at least 136,000 kg (300,000 lb). It warns ATC and following pilots that greater wake separation may be required.
ICAO defines Heavy as 136,000 kg or more, while the US FAA describes an aircraft capable of taking off at 300,000 lb or more. Because those rounded thresholds are not perfectly identical and individual variants differ, we use the aircraft’s officially assigned wake category rather than calculating it from a displayed weight.
Why does ATC say Heavy after a callsign?
The suffix makes the aircraft’s wake-turbulence category immediately clear to controllers and other pilots. Heavy aircraft can produce powerful wingtip vortices, so a following aircraft may require additional spacing during departure, approach or operations on closely connected runways.
The required separation depends on both the leading and following aircraft, the runway arrangement and the ATC procedure in use. Heavy does not grant priority, describe the aircraft’s performance or guarantee that turbulence will be encountered.
In a call such as Speedbird One Two Heavy, Heavy is a radio suffix rather than part of the airline’s flight number. Our explanation of the difference between a callsign, flight number, registration and aircraft type helps separate those identifiers.
Which aircraft use the Heavy callsign suffix?
Aircraft use Heavy because of their certificated category, not because they happen to be carrying a large payload on that flight. A lightly loaded Boeing 777 remains Heavy, while a fully loaded Boeing 737 does not become Heavy.
| Wake category | Typical examples | Spoken suffix |
|---|---|---|
Heavy, flight-plan code H | Boeing 747, 767, 777 and 787; Airbus A330, A340 and A350 | Heavy |
| Below the Heavy threshold | Boeing 737 and 757; Airbus A320 family; most regional jets | No Heavy suffix |
Super, flight-plan code J | Airbus A380 under applicable procedures | Super |
These are typical examples; the approved category for the exact aircraft variant and aviation authority is decisive. Being a wide-body is a useful clue but not the rule. The Boeing 757, for example, receives special wake treatment in some systems but is not called Heavy.
The Airbus A320 is normally filed as wake category M under ICAO rules, not Heavy. See how its ICAO aircraft type and wake code are entered for a practical comparison.
Some airports use more detailed wake-recategorisation groups behind the scenes. Those groups can change the spacing applied by ATC without giving pilots a new radio suffix to invent.
When should pilots say Heavy on the radio?
Put Heavy immediately after the aircraft callsign when the published wake category requires it. ICAO phraseology requires the suffix on initial contact with an ATC unit, while US guidance expects Heavy and Super aircraft to use their suffix in radio communications; local procedures determine how often it is repeated in shortened exchanges.
- Spoken call:
London Control, Speedbird One Two Heavy, flight level three five zero. - ICAO flight plan: enter wake category
H; a type-and-category combination may appear asB77W/H. - Written callsign: do not add the word Heavy to the airline designator and flight number. It remains a spoken wake-category suffix.
ATC may also include Heavy when addressing the aircraft. Pilots should follow the filed category and local phraseology rather than adding the suffix simply because an aircraft looks large.
Why does flight simulator ATC not say Heavy?
Simulator ATC usually omits Heavy when the aircraft metadata or filed wake category is missing, incorrect or unsupported by that ATC system. Common causes include:
- Wrong wake category: the flight plan was filed as
Minstead ofH. - Incorrect callsign setup: Heavy was typed into the callsign field instead of being represented by the wake category.
- Missing add-on data: an aircraft visually modelled as a heavy jet has incomplete ATC metadata. In an editable legacy FSX aircraft configuration, the relevant setting may be
atc_heavy=1. - ATC limitations: some offline ATC engines do not reproduce every regional phraseology rule, even when the aircraft is classified correctly.
On an online controller network, file the correct ICAO aircraft type and wake category, then use Heavy after the spoken callsign. Our guide to setting up callsigns and flight plans on VATSIM covers the practical connection between the simulator, pilot client and live ATC.