I know that sometimes 757s will be given a heavy callsign on the radio. Why is that?
I know it's the case for ATA and also for North American. Is it becuase they do it for airlines that I like or another reason? ;)
Printable View
I know that sometimes 757s will be given a heavy callsign on the radio. Why is that?
I know it's the case for ATA and also for North American. Is it becuase they do it for airlines that I like or another reason? ;)
I always thought it was the weight of the plane, but the 757 alway is a heavy due to the extra spacing that is needed behind it
A heavy is an aircraft capable of takeoff with 255,000 pounds or more. Even if they don't weigh that much at takeoff, they still are considered heavies. The 757-200 is not a heavy while the 300 series is.
Found this on-line
From FAA Order 7110.65R - Air Traffic Control (Appendix A)
Also, they have a chart which lists the 752 as "Large" and the 753 as "Heavy"Quote:
"AIRCRAFT CLASSES- For the purposes of Wake Turbulence Separation Minima, ATC classifies aircraft as Heavy, Large, and Small as follows:
a. Heavy- Aircraft capable of takeoff weights of more than 255,000 pounds whether or not they are operating at this weight during a particular phase of flight.
b. Large- Aircraft of more than 41,000 pounds, maximum certificated takeoff weight, up to 255,000 pounds.
c. Small- Aircraft of 41,000 pounds or less maximum certificated takeoff weight."
While it doesn't refer to it directly in this paragraph, most places I've seen this referenced also include:
The exception to this is the 757- in the US only, it is considered a "heavy" due to the need for additional separation from other aircraft and its unique wake vorticies.
This makes sense. According to my math, an average 757-200 at its absolute heaviest possible weight tips the scales at ....literally....254,900 pounds.Quote:
Originally Posted by moose135
Sounds like the 255,000 mark that they made was specific to keep the 757 out of the 'heavy' arena, with the exception of wake turbulence requirements.
Moose you are correct in that its treated like a heavy b/c of its wake, but it is not called a heavy in the callsign.
I've seen otherwise. The reason I asked is because last week I heard a North American 757-200 referred to as a heavy at two different airports during an empty ferry flight.Quote:
Originally Posted by njgtr82
Some airports do opt to refer to a 757 as "heavy" MDW being one of those. It is the largest aircraft to fly into MDW as well. At ORD occationally the Mexicana 757-200s would refer to themselves has "heavy".
Senga
Hmm, I thought only the 753 is a heavy. I guess I am wrong!
Some 752's do have added MTOW. AmTran and No Am both do as Phil mentioned. Senga, I've never heard of particular facility calling 752's (that dont have that added weight) heavies. Everyone working traffic knows who is a heavy and who is not, all stated in the .65 *the doc that moose posted*
Doesn't matter if it's empty or not, a heavy is a heavy, based on max takeoff weight. As I noted, 757s are typically handled as heavies due to wing vortices, so the controller may have called them "Heavy" to denote this.Quote:
Originally Posted by Phil D.
Interesting topic. I always was under the impression that the -300 was a heavy and a -200 was not. Everytime I've flown on UA's 752s and tuned into channel 9, we've never been referred to as "heavy". About a week and a half ago, we landed behind a UA777 and a BA777, both were called heavy, but we were not. I think we had a 319 or 320 land behind us, and the controller advised him that we were a 757 and to caution for wake turbulence.
What is it about the 757 that causes wake turbulence to be so different from any other heavy? Any what is a pilot--given a "caution wake turbulence"--supposed to do? Ask the tower if he can slow down? (not likely) Steer out of the way? Brace?Quote:
Originally Posted by USAF Pilot 07
It's handy information, especially if you're flying an aircraft that's lighter or smaller than the one generating wake turbulence in front of you. Since wake sinks, the typical evasive maneuver (from a GA perspective) would be to stay slightly above the glidepath of the culprit. Or, if you're in line to take off, just wait two minutes for it to dissipate and try to get in the air before the generating aircraft rotated.Quote:
Originally Posted by uplander
It's also important to note that wake turbulence is produced as soon as the wings start producing lift, which means that it's an issue for most of the takeoff roll and not just when the aircraft becomes airborne.
There's a whole 'nother big ball of wax that deals with drifting vortices, light-quartering tailwinds, etc., but that's for another time.
And not to put you on the spot, Moose, but do you have any exhilerating military experiences with wake turbulence from your "Top Gun" days? ;)
Brian
Never really remember any serious wake turbulence encounters, well, except for some of the bouncing around you got as number 2 or 3 (or 4!) on a MITO. That's minimum interval take off - 12 seconds spacing between tankers - when you aren't the lead dog on a wet MITO, the view never changes :DQuote:
Originally Posted by Futterman
A bigger factor we faced in the tanker was the bow wave effect of large receivers (C-5, KC-10). Think of standing along side the highway when a large truck goes by at speed - you get a blast of air, that's the "bow wave" of air being pushed aside by the truck. Aircraft do the same thing, and when a large receiver pulled up under us (and the nose of the receiver would be under the horizontal stab of the tanker) the bow wave would push the tail up. If you don't keep up with the trim, you get a very nose-down push, not the kind of thing you want with a *very* large aircraft pulling up under you :shock:
Usually, we would fly tanker A/R with the autopilot on, and for most receivers the autopilot would compensate, but for the big guys, especially if they closed quickly, you needed to run some trim in manually to keep up.
Between bow wave effects off the receiver, and downwash effects off the tanker wing, is it any wonder the air refueling manual has this to say:
http://moose135.smugmug.com/photos/123840257-M.jpg
Moose, that was one of the most interesting things I've ever read on this site. Thank you.
Isn't there also the possibility of a stall immediately upon takeoff behind a large plane. Liek where the on-ground wake turbulence gives the next aircraft added lift, and once that plane goes airborne earlier than the wake turbulence, it's like loss of air and the potential for stall. Make sense?
Pretty intense stuff, Moose! Thanks for sharing.
"Loss of air"?? Whatever. :)Quote:
Originally Posted by Phil D.
Sounds like you're talking about two different things here. The direct effect of flying into wake turbulence is an uncontrollable rate of roll, which may very well induce a stall at some point. Remember what exactly wake turbulence is - just wingtip vortices. It would be kind of like putting a rubber duck in a full, still tub, then pulling the drain and watching how the water just spins the thing around. In fact, that whipping sound you hear after a plane passes over you at Landing Lights Park is actually the air swirling and snapping around (wake is invisible unless, as you see below, you fly through a cloud).
Simply put, if you go into this:
http://us.airliners.net/photos/middle/3/3/0/1008033.jpg
You come out like this:
http://chapter1297lusitanos.planetac...ssnaVortex.jpg
What you're talking about with stalling is more in line with something called ground effect, which is a phenomenon that allows a plane (typically light) to get airborne at a slower-than-normal speed. But that's neither here nor there.
Brian
the 752 is considered a heavy for wake turbulence avoidance reasons. it is given the same spacing as a 767 or 777, regardless of how much the airplane weighs at the time. as said before, some airframes are capable of exceeding the 255,000 lb limit. not sure if in those cases they are called heavy. most times, the -200 isn't heavy. the -300 always is.
avoiding wake turbulence can be tricky some times. say you're following a G-IV in my A36. to avoid the wake turbulence he produces you need to stay above his flight path. if he touches down at the 1000' marker than i would float a little until about 1500' or 2000' before touching down. if i were taking off behind him then i would first be required to wait the 3 minutes before being cleared for t/o. then, i would rotate and climb out well before the other airplane rotated, and climb out above his climb path. if you're lucky enough to have a crosswind then you simply fly upwind and above the flight path of the other airplane.
diclaimer: it's been a while since i've been to ground school. and i need to update my manuals, i still have the 7110.65P
Thanks, Phil. Actually, I was going through a box of stuff this weekend and came across some of my old KC- manuals...sure brings back some memories.
As Brian said, I don't think running into wake turbulence will help you take off any sooner. Sounds like you are thinking more of ground effect, where you can lift off at a lower than normal airspeed, then keep the plane down low (usually no more than one wingspan's distance from the ground) while you build up airspeed. That's actually a normal way to take off from a soft field.
And one more little "war story" from the tanker. During initial training, and occasionally at the unit with an IP, we would fly a Landing Attitude Demo - fly a normal approach down to the flare, then with the nose up in the landing attitude, add some power and fly down the runway in ground effect until you go around. It was a good way to teach a new pilot the proper visual picture for landing. I think we had to do one every six months or so once qualified, and it was a good refresher when you were in a little bit of a landing "slump" (Not that I would know anything about that)
Matt, excellent description of how to avoid running into wake turbulence, and you can download a PDF version of 7110.65R at http://www.faa.gov/ATPUBS/ATC/ATC.pdf
Hey, thanks for sharing those stories.
I guess that warning in the manual would be like having something like this on the underside of the horizontal stabilizer:
http://logo.cafepress.com/5/692205.gif
:)
Brian,
How did you get Sam Chui take air-to-air picture of you flying?
http://chapter1297lusitanos.planetac...ssnaVortex.jpg
Wow!
;)
Mario,
Sam was there, but that's not his shot. He hasn't released his to the public yet, but I have permission to give you a sneak preview of the brilliant product of his fisheye lens:
http://www.airliners.net/uf/53688234...2870cqdqdm.jpg
What a day!
Brian
Previously the heavy designation applied for aircraft 300,000lbs and higher . now it's 255,000lb Additionally outside of the US , the heavy suffix is not used.
the controller knows it's a heavy from the Flightplan's filing . It looks something like this
the B752/H <- The "H" indicates heavy
FPL-AMT453-IS
-B752/H-CSSXWRIY/S
-PHNL0830
-N0486F330 DCT XXX B453 SIMLU/M084F330 B453 SPEES/N0485F330 B453
I also found some items you all might find interesting reading , or at least some of it as it pertains to the 757
http://www.ll.mit.edu/AviationWeather/W ... iction.pdf
this one briefly talks about a cessna Citation accident which was the result of a 757's wake
http://www.mbe.doe.gov/me2-4/oam/docs/fsn/9401.htm