Wake turb. B737-800

[alatriste]

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.

[LEM]

Who does consider it a heavy?

[alatriste]

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, IŽll better check with my company.

[avioniker]

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

[LEM]

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!

[avioniker]

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)