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 Why Is A Heavy Called A Heavy?
 c5load From United States of America, joined Sep 2008, 917 posts, RR: 0Posted Sat May 15 2010 09:07:18 UTC (4 years 10 months 2 weeks 5 days 14 hours ago) and read 3774 times:

 I know what makes an airplane annotated as a "heavy" is the t/o weight is more than 255,000 lbs, correct? But what is the reason behind the "heavy" callsign? Is there a real big difference in wake vortices between a plane that weighs 257,00 lbs and one that weighs 254,000 lbs. One is going to be called a heavy and the other will not, right? Is this callsign simply for advisory reasons for airplanes that are following? Does that make the distance between the two greater? For example, the 757 was for a long time called a heavy, but now is not. I doubt the wake behind it has changed, so does that mean, by rule, you can follow a 757 closer now than when it was a heavy?
 "But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
 tdscanuck From Canada, joined Jan 2006, 12710 posts, RR: 80 Reply 1, posted Sat May 15 2010 10:34:01 UTC (4 years 10 months 2 weeks 5 days 13 hours ago) and read 3733 times:

 Quoting c5load (Thread starter):I know what makes an airplane annotated as a "heavy" is the t/o weight is more than 255,000 lbs, correct? But what is the reason behind the "heavy" callsign?

Separation due to wake turbulence for the trailing aircraft.

 Quoting c5load (Thread starter):Is there a real big difference in wake vortices between a plane that weighs 257,00 lbs and one that weighs 254,000 lbs.

Not really big, unless there's a particularly bad high-lift implementation, but there is a difference. Much more importantly, you need to draw the line somewhere since the system has to be usable in the practical ATC environment.

Something at the very low end of the heavy class is not realistically any more threatening than something at the very high end of the non-heavy class.

 Quoting c5load (Thread starter):One is going to be called a heavy and the other will not, right?

Generally, yes. I believe, if wake turbulence testing dictated it, an aircraft could be labelled heavy even if it's below the weight threshold.

For airplanes in trail, and for ATC to setup the correct spacing.

 Quoting c5load (Thread starter):Does that make the distance between the two greater?

Generally, yes, but it depends what's following what.

Tom.

 AR385 From Mexico, joined Nov 2003, 7044 posts, RR: 35 Reply 2, posted Sat May 15 2010 13:43:48 UTC (4 years 10 months 2 weeks 5 days 9 hours ago) and read 3626 times:

 It has to do with the amount and intensity of the wake turbulence they generate. I´m not sure if it has to do with the weight per se. The 757 is not that big, but it is a big wake turbulence generator. Thus, the call sign "heavy" calls the attention of ATC to give the required separation as well as to anyone following behind on the approach sequence or take off.
 Caryjack From United States of America, joined May 2007, 368 posts, RR: 0 Reply 3, posted Sat May 15 2010 13:58:26 UTC (4 years 10 months 2 weeks 5 days 9 hours ago) and read 3616 times:

 Quoting c5load (Thread starter):One is going to be called a heavy and the other will not, right?

Not necessarily.    The B-757 is an airliner that sits on the fence between the Large and Heavy weight classifications. It generally weighs into the Large class but is able to generate wake turbulence similar to a much larger Heavy. For that reason the 757 has been the subject of much wake turbulence discussion here on A.net. I've attached such a thread.

Why Is 757 A "Heavy"? (by web500sjc Feb 13 2010 in Tech Ops)

I also understand that B-737s are able to generate a disproportionately large wake turbulence and that winglets mitigate this turbulence. I haven't read similar posts concerning winglets on the B-757.
Thanks,
Cary

 tdscanuck From Canada, joined Jan 2006, 12710 posts, RR: 80 Reply 4, posted Sat May 15 2010 14:52:18 UTC (4 years 10 months 2 weeks 5 days 8 hours ago) and read 3592 times:

 Quoting AR385 (Reply 2):It has to do with the amount and intensity of the wake turbulence they generate. I´m not sure if it has to do with the weight per se.

To first order, the total vorticity shed is a function of weight, speed, and span only. What differs from aircraft to aircraft is how the vorticity is distributed in the wake.

Tom.

 71Zulu From United States of America, joined Aug 2006, 3096 posts, RR: 0 Reply 5, posted Sat May 15 2010 16:31:46 UTC (4 years 10 months 2 weeks 5 days 7 hours ago) and read 3550 times:

 Quoting c5load (Thread starter):I know what makes an airplane annotated as a "heavy" is the t/o weight is more than 255,000 lbs, correct?

300,000 lbs

 The good old days: Delta L-1011s at MSY
 XFSUgimpLB41X From United States of America, joined Aug 2000, 4253 posts, RR: 36 Reply 6, posted Sat May 15 2010 22:20:47 UTC (4 years 10 months 2 weeks 5 days 1 hour ago) and read 3445 times:

 255,000 pounds or greater MTOW capability is the dividing line in the US. Will 257,000 pounds make a huge difference over 255? No.... a line has to be drawn somewhere. FWIW, no 757 of any type or certification carries the "heavy" designation as of 1 May in the US.
 Chicks dig winglets.
 71Zulu From United States of America, joined Aug 2006, 3096 posts, RR: 0 Reply 7, posted Sat May 15 2010 23:46:28 UTC (4 years 10 months 2 weeks 4 days 23 hours ago) and read 3418 times:

 Quoting XFSUgimpLB41X (Reply 6):255,000 pounds or greater MTOW capability is the dividing line in the US.

Did they change it again? This says it's now 300,000 lbs.

http://www.faa.gov/documentLibrary/media/Notice/N7110.525.pdf

 Quote:Policy Change. Appendix A is being revised to harmonize FAA weight category standards with those of the International Civil Aviation Organization (ICAO). All aircraft that weigh more than 41,000 pounds, maximum certificated takeoff weight, up to but not including 300,000 pounds, will now be classified as a “Large” aircraft according to FAA standards. Aircraft capable of takeoff weights of 300,000 pounds or more, whether or not they are operating at this weight during a particular phase of flight, will now be classified as a “Heavy” aircraft according to FAA and ICAO weight classification standards.

 The good old days: Delta L-1011s at MSY
 XFSUgimpLB41X From United States of America, joined Aug 2000, 4253 posts, RR: 36 Reply 8, posted Sun May 16 2010 18:29:24 UTC (4 years 10 months 2 weeks 4 days 5 hours ago) and read 3227 times:

 They must have just changed it to 300,000 pounds. It was 255,000 pounds up until May 1.
 Chicks dig winglets.
 HAWK21M From India, joined Jan 2001, 31716 posts, RR: 55 Reply 9, posted Mon May 17 2010 00:29:54 UTC (4 years 10 months 2 weeks 3 days 23 hours ago) and read 3162 times:

 So wef 8th April 2010 41000 - 300,000lbs = LARGE 300,000lbs + = HEAVY Any reason stated was to harmonize the same with ICAO. Is there any more information on its background. regds MEL.
 Think of the brighter side!
 andyinpit From United States of America, joined Sep 2007, 320 posts, RR: 0 Reply 10, posted Mon May 17 2010 14:08:51 UTC (4 years 10 months 2 weeks 3 days 9 hours ago) and read 3046 times:

It's back down to 255,000
And no there isn't that much difference, but it's there for when there IS a large difference and there isn't any confusion on when to issue it. Just make it blanket for everything over 255 and you won't forget it.

 HAWK21M From India, joined Jan 2001, 31716 posts, RR: 55 Reply 11, posted Tue May 18 2010 03:53:24 UTC (4 years 10 months 2 weeks 2 days 19 hours ago) and read 2934 times:

 Quoting andyinpit (Reply 10): It's back down to 255,000

regds
MEL.

 Think of the brighter side!
 andyinpit From United States of America, joined Sep 2007, 320 posts, RR: 0 Reply 12, posted Wed May 19 2010 11:17:44 UTC (4 years 10 months 2 weeks 1 day 12 hours ago) and read 2751 times:

 Sorry I dont have a link. Just something I signed off on in our Read and Initial binder. If I can find the change in the 7110.65 I'll let you know
 KELPkid From United States of America, joined Nov 2005, 6486 posts, RR: 3 Reply 13, posted Wed May 19 2010 13:02:00 UTC (4 years 10 months 2 weeks 1 day 10 hours ago) and read 2724 times:

 Quoting tdscanuck (Reply 1):Not really big, unless there's a particularly bad high-lift implementation, but there is a difference.

So are you saying that the 757 has a bad high lift device implementation?

 Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 KELPkid From United States of America, joined Nov 2005, 6486 posts, RR: 3 Reply 14, posted Wed May 19 2010 13:05:27 UTC (4 years 10 months 2 weeks 1 day 10 hours ago) and read 2722 times:

 Quoting XFSUgimpLB41X (Reply 6): 255,000 pounds or greater MTOW capability is the dividing line in the US. Will 257,000 pounds make a huge difference over 255? No.... a line has to be drawn somewhere. FWIW, no 757 of any type or certification carries the "heavy" designation as of 1 May in the US.

So here's one:

The 757-300 max takeoff weight is 272,500 lb. Is it conceivable that a 757-300 can take off as a "heavy" and land with no "heavy" on the callsign?

 Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 XFSUgimpLB41X From United States of America, joined Aug 2000, 4253 posts, RR: 36 Reply 15, posted Thu May 20 2010 20:30:05 UTC (4 years 10 months 2 weeks 3 hours ago) and read 2565 times:

 Quoting KELPkid (Reply 14):So here's one: The 757-300 max takeoff weight is 272,500 lb. Is it conceivable that a 757-300 can take off as a "heavy" and land with no "heavy" on the callsign?

Please notice that I wrote "capability" i.e. certification, not actual weight. If the airplane is certified above the heavy dividing line, then it is always a heavy regardless of actual weight.

The 757 of all types is no longer a heavy as of the first part of April, as previously stated. Apparently the line moved to 300,000 pounds.

 Chicks dig winglets.
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