Landing Behind a Heavy

[Maverick2167]

Just curious,

Say you are a medium aircraft ( Airbus 321) landing behind a heavy (airbus 330) with radar separation of 5nm on the approach. Winds quarterly at about 7-9kts, high elevation airfield (3000ft AMSL), flat terrain, and early morning thermals. Could the wake from the heavy aircraft contribute to an environmental perturbance i.e. make you float during the flare (aircraft not sinking as usual as flare commenced and Thrust retarded)

Thanks

[blind pew]

Thermals can do that as do inversions but as you’ve mentioned early morning thermals the inversion is likely to be much higher. Did a go around followed by further wake turbulence on second approach at LHR after sea breeze front had changed runways on to easterlies whilst we had a tail wind on approach.
Seen wind switch 180 degrees with an overall strength change of more than 10 knots through thermal release.

[Maverick2167]

Originally Posted by blind pew

Thermals can do that as do inversions but as you’ve mentioned early morning thermals the inversion is likely to be much higher. Did a go around followed by further wake turbulence on second approach at LHR after sea breeze front had changed runways on to easterlies whilst we had a tail wind on approach.
Seen wind switch 180 degrees with an overall strength change of more than 10 knots through thermal release.

Thanks, the winds were varying at short final (100-50ft RA) but not to the extent of becoming tailwinds. The runway orientation was 27, and from 1000ft AGL till 400ft RA the W/V were 200-230degrees/7-8 knots, and by 100ft -50ft RA- 176-200- 7-8knot. Although I agree that thermals and inversion could be responsible, I was wondering if the vortices from the heavy aircraft could linger within the touchdown zone and add an additional ground effect.??

[BraceBrace]

AFAIK wake vortices create short term turbulence and roll motions. Ground effect is something completely different. In ground effect you speed remains ’normal’, vortices would create large speed fluctuations and possible instant roll.

[Maverick2167]

Originally Posted by BraceBrace

AFAIK wake vortices create short term turbulence and roll motions. Ground effect is something completely different. In ground effect you speed remains ’normal’, vortices would create large speed fluctuations and possible instant roll.

Agreed. Just the top of my head- the pics that you see in textbooks- wake vortices are something like doughnuts (rings) trailing behind the wingtips right? So on the ground and near to touchdown, wouldn't these doughnuts or rings be broken by the tarmac and thus form some sort of half-ring cushion of air?

[MarkerInbound]

Really nice video someone took on a foggy night. The left side vortex seems to almost bounce off the ground.

You Tube

[Amadis of Gaul]

Originally Posted by Maverick2167

Just curious,

Say you are a medium aircraft ( Airbus 321) landing behind a heavy (airbus 330) with radar separation of 5nm on the approach. Winds quarterly at about 7-9kts, high elevation airfield (3000ft AMSL), flat terrain, and early morning thermals. Could the wake from the heavy aircraft contribute to an environmental perturbance i.e. make you float during the flare (aircraft not sinking as usual as flare commenced and Thrust retarded)

Thanks

Absolutely.

[mustafagander]

When it comes to landing in the possible wake vortex of a previous aircraft, cross wind is your best friend to drift them off the runway.