7th Jul 2012, 02:10
Maybe this question is a little bit stupid, but hope to got some information about it. According to the regulation, two aircraft should be 1,000ft vertical separated if less than wake turbulence horizontal separation, but wake turbulence is sinking, if two aircraft are totally merged and only 1,000ft vertical separated, will the traffic below concure wake turbulence of the one above??
1000ft separation is considered as standard in most places and shall be established if radar separation not be provided and not just for wake. Considered that 1000ft is enough for wake to dissipate,but there were few encounters of wake with A380 when flying 1000ft below it. So I'm aware that some countries require 2000ft vertical with A380 or up to 17nm if in trail.
7th Jul 2012, 07:13
The wake sinks slowly and is less destructive the longer the time passes...
Two aircraft 1000ft apart but with apparently no other forms of separation will not cause the bottom aircraft to encounter the wake from the above. More likely to be effected by sinking wake when 2-3 minutes behind and 1000ft below. It is rare but not unheard of.
But As far as I know there are no wake turbulence separation where a vertical standard exists unless one or both aircraft are super-sonic.
7th Jul 2012, 22:06
To answer the OP question then no, totally merged traffic 1000ft apart will not be affected by wake. There are instances however where traffic following a few miles behind 1000ft below have encountered wake (and sometimes offset depending on wind direction and strength). The main culprits giving off wake in this manner are the A380, MD11 and B757 (I think the -300 variant) normally climbing.
In the uk enroute environment there are currently no procedures to provide wake separation, just 5nm/1000ft or 2000ft where applicable due to non-RVSM airspace. Standard separation is doubled if one aircraft is supersonic, but not due to wake turbulence.