I fly a heavy but have still experienced nasty jolts passing through 380 wake.
To be safe I would be conscious of wake even up to 40 NM away. That would equate to around 5 minutes. Sure that's probably a bit too far to really effect you but I wouldn't play around. Inside of 20NM I would consider wake turbulence critical.
If you are visual with the aircrafts contrail then expect the wake to start with the contrail and then descend below it. So if the aircraft is we'll passed you don't worry about flying through it's contrail if it's near then don't
Yes it's totally dependent on atmospheric conditions but as a rule of thumb if passing behind, take the wake aircrafts distance away from you when you expect to cross it's wake trail and multiply by 50 to get a reference altitude then take a window of plus/minus 500 feet. I.e. if aircraft is 10NM then x 50 = 500ft. So take a window of 0-1000ft. At 20NM x 50 = 1000ft so window is 500-1500ft. If you're passing behind at these altitudes then take wake seriously. (Past 10NM I would even suggest adding plus 1000ft to the reference altitude)
It's not an exact science but I hope it keeps you safe.
Last edited by Airmann; 13th Nov 2018 at 01:30.