Wake turb. B737-800
 

Winglets reduce wingtip vortices and thereby induced drag so that specific range is increased.
If the above statement is true, Why 737-800 is considered a "heavy" for separation porpouses if its weight is well below 136.000 Kg? Winglets should reduce the power of their wingtip vortices and, therefore, the wake turbulence behind it.

Thanks again.

Who does consider it a heavy? :confused:

We have received few weeks ago instructions from our company to consider B737-800 as a "heavy" for traffic separation during take off and aproach manouvers. I guess this recomendation is caused by some recently incident. Anybody out there know about this restriction?
If nobody is considering 737-800 as H, I´ll better check with my company.

The NG wing without winglets is very similiar to the 757 wing which produces incredible vorticies. Maybe that has something to do with it.
Here's a picture:

http://www.b737.org.uk/winglets.htm

Yes, but 757's vortices have been officially recognised as dangerous, and the separation increased from 3 to 4 miles for a medium, while heavy is 5 nm.
Haven't seen so far anything official about 737NG.
Let me know if I missed something, thanks!

The 757 got the "rating" after the FAA did smoke trail tests with the FAA's 727 (with wingtip mounted smoke generators) flying ahead of a 757 and watching the patterns off the 757 wing vorticies.
I don't think the 727 is still equipped so I'm sure the 737 hasn't been tested. (yet) ;)