Heavy??

[CHIVILCOY]

I have often wondered why the term "HEAVY" after a flights callsign only seems to be used by larger aircraft.
I would appreciate if anyone can explain the reason for this?

[carbonfibre]

Yeah think i can help with this one

Officially the Prefix heavy is for an aircraft weighing more than 136,000 Kg's

Unless your realistic then an aircraft weighing on 20,000kg's is heavy too depends if your under it.

So anything over 136,000kgs is good, mainly used for the likes of aircraft like the 767-300, 747 and larger airbuses, DC10, tristars. That type of aircraft.

Also gives an indication of the wake turbulance that following aircraft are likely to en counter so ATC can maintain the required seperation

Hope this helps

[McD]

ICAO defines three wake-turbulence categories of aircraft (individual countries may have additional categories):


LIGHT = max certificated takeoff weight less than 7000 kg (15,500 lb)
MEDIUM = between 7000 kg and 136,000 kg
HEAVY = higher than 136,000 kg (300,000 lb)


The word "heavy" is stated after the call sign of heavy aircraft, because this category of aircraft poses the greatest risk to other aircraft in terms of wake turbulence. Emphasizing the presence of a heavy aircraft helps ATC to optimize arrival/departure planning, and gives operators of other aircraft increased situational awareness.

[Knold]

Well the categories doesn't follow the mass limits strictly. Take the 757 for instance. It has a MTOM of around 100 tonnes, but it's still in the heavy category as far as I know ( or at least in practis I believe). This is due to short wings producing a great wing load and therefore powerful vortexes.

[Spitoon]

In the UK we differ slightly from the ICAO classification. Here we use four categories still based on their maximum total weight at take-off as follows:
* Heavy: 136 000 kg or greater
* Medium: less than 136 000 kg and more than 40 000 kg
* Small: 40 000 kg or less and more than 17 000 kg
* Light: 17 000 kg or less
But there is also a note that says 'It will be noted that several aircraft types have been grouped in vortex wake categories which do not conform to those listed above. For example, the B707, DC8, VC10 and IL62 have been classified as MEDIUM as experience has shown that the characteristics of these types conform more to that group.'. In the reference table the B757 is classed as a Medium but the detailed rules say to use 4 miles instead of 3 when there's another Medium behind a B757.

[CHIVILCOY]

Thanks to all who replied. ;)

[eyeinthesky]

Can anyone tell me why it seems common practice in USA and with US airlines for them to suffix their callsign with 'Heavy' on every call (if they are of course in the Heavy category)? Surely the only phase at which this becomes important is in the approach phase, since when en route we are usually using 5 mile separation anyway. Seems an unnecessary extra word in each transmission.

[vector4fun]

Use of the term "Heavy" is required in the terminal environment by regulations. From the 7110.65:



2-4-14. WORDS AND PHRASES

Use the words or phrases in radiotelephone and interphone communication as contained in the P/CG. The word "heavy" shall be used as part of the identification of heavy jet aircraft as follow:

TERMINAL. In all communications with or about heavy jet aircraft.

EN ROUTE. The use of the word heavy may be omitted except as follows:

a. In communications with a terminal facility about heavy jet operations.

b. In communications with or about heavy jet aircraft with regard to an airport where the en route center is providing approach control service.

c. In communications with or about heavy jet aircraft when the separation from a following aircraft may become less than 5 miles by approved procedure.

d. When issuing traffic advisories.

EXAMPLE-
"United Fifty-Eight Heavy."

NOTE-
Most airlines will use the word "heavy" following the company prefix and flight number when establishing communications or when changing frequencies within a terminal facility's area.

[Young Paul]

Hea -veeee, man! :cool: