What does "heavy" mean in an aircraft's radio ID?

Any airplane with a certified maximum takeoff weight of more than 255,000 pounds must identify itself as a "heavy" aircraft in its initial radio call.

Heavy Aircraft

As per FAR/AIM 2012 (Federal Aviation Regulations / Aeronautical Information Manual), Section 5-1-9, "International Flight Plan (FAA Form 7223-4) - IFR Flights (For Domestic or International Flights), para b, "Explanation of Items Filed in FAA Form 7233-4," Entry 3, "Item 9. Number, Type of Aircraft Wake Turbulence Category," (c) "Wake Turbulence Category:"

"(1) H - HEAVY, to indicate an aircraft type with a maximum certified takeoff weight of 300,000 pounds (136,000 kg), or more."

This is again affirmed in the AIM Glossary, under "Aircraft Classes:"

"a. Heavy - Aircraft capable of takeoff weights of 300,000 pounds of more whether or not they are operating at this weight during a particular phase of flight."

The term "heavy" is required because aircraft meeting this criteria are more likely to generate wake turbulence that's a problem for other aircraft. As a result, Air Traffic Control establishes greater separation during all phases of flight between these aircraft and others.

A Boeing 757 is NOT a heavy jet, but has additional rules as it throws of as much wake turbulence as some heavies. The term Heavy is always in the call sign and the separation standards with a Heavy are higher than other aircraft. If you fly to close and behind one of them, you can get knocked over or worse.

The number 255,000 pounds was picked for a reason.. it was the MAX Gross Take Off Weight (MGTOW) of the 757 when it entered service. For WHATEVER reason... the powers that be decided that it would not be considered a "heavy" jet for the wake turbulence seperation mins.

I can tell you that a B-737 can throw a wingtip votice that can knock you pretty darn well if you catch it at the right moment... so basically.. this is just a guideline.. and no one went back and checked their AIM to recite WHEN the wing tip vortices are at the most powerful?? or parallel runway ops with cross winds of how much? regarding seperation ... yup... it's all in there... Best thing is just fly a heavy jet and then you don't have to deal with all that... DOH !

Aircraft with operating weight of 255,000 lbs or greater and generally the Boeing 757. The aircraft does not have to be operated at the MTOGW (max take off gross weight) to be considered a heavy.

previous answer if wrong.

term heavy is applied to any aircraft with a weight of more than 220,000 lbs total at departure. the term heavy remains regardless if the aircraft got lighter because of expended fuel,

one purpose is to tell the ATC to allow more separation between large and smaller aircraft because larger aircraft tend to displace more air and the turbulence caused by their passage can be lethal to smaller aircraft following behind. (The aircraft itself does not need to be large, just the aircraft behind needs to be smaller. For example, a cessna close behind a 737 is very bad. Even though a 737 is a medium aircraft, the cessna can be flipped over by its wake turbulence)

It means "containing more than one flibe." If there is one flibe or zero flibes, it is a "light" aircraft.

It spcifies if the aircraft is a widebody (twin aisle. ex:: 767)