Why heavy?

[amenofiiv]

Hi!!!
Just a curiosity: depending on what an aircraft has the adjective "hevy"? Is for the weight? Is for the wingspan? Both? None of these hypotesis? Thaks
a lot, I know that here there are many many people that know this!!!
vittorio

[ivo]

I think its for weight, and 'heavy' is over 300,000 lbs.



Post Edited ( 03-23-06 15:19 )

[amenofiiv]

Thanks Ivo!!!
If someone elese had the ideas a little bit more clear is welcome! :-) Thanks however, your answer has been illumnating!
Vittorio

[ivo]

I might be wrong, but I think I heard it in a ITVV video where someone said that 'heave' was appointer to the aircraft is the aircraft was
over 300,000 lbs. But I don't know if he meant 300,000 lbs. MTOW or 300,000 lbs. GW.

[DBE]

Ok: here you go..

The term "heavy" is in relation to the amount of wake turbulence (i.e. vortices) generated by an aircraft.

The strongest vortices are produced by heavy aircraft, flying slowly, in a clean configuration. For example, a large or heavy aircraft that must
reduce its speed to 250 knots below 10,000 feet and is flying in a clean configuration while descending, produces very strong wake.

So, in order for other aircraft to be warned about eventual turbelences generated by such giants, the "heavy" term is added to their callsign.

Hope this help!

[ivo]

Thanks DBE, but do you know the cutoff weight?



Post Edited ( 03-23-06 23:55 )

[DBE]

Yep: you basically attempt to land a couple of Cessnas behind so-called "large-bodied" aircraft.

As soon as your Pax start reaching for the barf-bag, it's a heavy!

Sorry: but, as mentioned, it's got nothing to do with weight, but with aerodynamics!

[AKLupine]

While the weight for a HEAVY used to be 300K, it has been reduced. The current weight catagories are:

HEAVY: Aircraft capable of takeoff weights of 255,000 pounds or more whether or not they are operating at this weight during a particular phase of flight.

LARGE: Aircraft that are more than 41,000 pounds maximum certified takeoff weight, up to 255,000 pounds.

SMALL: Aircraft of 41,000 pounds or less maximum takeoff weight.

This is for the purposes of wake turbulence separation. From here there are pages of rules and guidlines on how to apply those rules for both
terminal and enroute. As with all rules worth their salt there is an exception: the Boeing 757 is classed as a heavy in most cases or listed
specifically. There is also the sub-catagory of SMALL+ which is used for aircraft of more than 12,500 operating within Class B airspace.

[amenofiiv]

Wow, how many answers!!
So, basically, I have to guess that any aircraft heavier than a 757 is "heavy"... I guess that weights (obviously) and wake turbulencies are greater
than others... Am I wrong?
Bye! Vittorio

[AKLupine]

BASICALLY, sorrta First off, you can look at the Boeing or ScAirbus sites and find the aircraft information for MGTW. The 757 I BELIEVE was
classified as a heavy due to it being designed as a narrow body 767, though the 753 IS able to get it up at 256,000. You can also look in the .cfg
file of the aircraft in question as the weights are listed in there, though not always a reflection of the RW aircraft. As for the wake being bigger,
well, I'll take it as a simple yes as I'm a controller not an aerodynamisist (and one who at the writing of this has not had his first mug of coffee)

[detpilot]

HEAVY: Aircraft capable of takeoff weights of 255,000 pounds or more whether or not they are operating at this weight during a particular phase
of flight.

That's the correct answer. The 757 is the exception, I have seen 752s and 753's as heavies, and I have seen both operating withouth the heavy
designation.

[amenofiiv]

Thanks to all!! Now I'm happy!
vittorio

[olseric]

HEAVY used to be 300K

Still is via ICAO standards. So, in most countries, heavy is MTOW over 300,000 lbs.

But, via FAA, 255,000 lbs.

[Full_Throttle0]

i wanna fly in a glider behind a 747. wait one those huge airbus frieghtetrs (i think are 4 in total) that are used to ferry parts to and from
airbus factories, ill find a pic im not sure what its called (maybe guppy or skylink?)....

brb...



that's it i wanna fly in that things wakes, if my glider doesn't stall or fall apart or somthing

[Drew]

That plane just looks sooooooooooo wrong