Landing behind a heavy jet with wake turbulence on final
You are flying a Cessna 182 on the ILS to Runway 18C, 4 NM from touchdown at 110 KIAS, established on the 3° glidepath. A Boeing 777 has just landed ahead of you and the tower clears you to land, adding 'caution wake turbulence, traffic was a heavy Boeing 777, wind 190 at 6 knots'. The 777's touchdown point was about 900 ft past the threshold. The runway is 3,600 m long, dry and level. The controller also asks whether you can accept a tighter interval to the aircraft behind you, which is a turboprop on a 3 NM final. Visibility is good and there is no low-level cloud.
1. Describe where the 777's vortices are now and how they will behave between this moment and your touchdown.
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Where they are. For an arriving aircraft, vortices are generated along the flight path wherever the wing is developing lift - from the threshold area down to the touchdown zone. The strongest ones form where the 777 was slow, heavy and clean, near its 900 ft touchdown point, and the generation effectively stops there.
How they behave. They form as a counter-rotating pair trailing from the outboard wingtips, spaced roughly three-quarters of a wingspan apart. They sink at about 300–500 ft/min and drift with the wind. With the wind 190 at 6 kt, almost aligned with the runway, drift is small and slow - the vortices will sit close to the runway and near the centreline rather than being blown clear. On a light-wind day they also decay more slowly; expect several minutes of hazard, not seconds.
What that means. Your 4 NM at 110 KIAS is only about two minutes behind the 777. Its vortices will still be over the touchdown zone, at or below your glidepath, when you arrive.
2. What is your plan for the approach and landing, and what do you ask ATC for?
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Plan.
- Stay on or slightly above the glidepath. Never below it - sink puts you into the region where the vortices have descended.
- Aim to touch down beyond the 777's touchdown point, past about 900 ft, and land firmly rather than floating. With 3,600 m available, a long landing is free.
- Do not plan a short landing in the touchdown zone, however neat it would look.
- Keep the approach stable and avoid a low, shallow, power-on float that leaves you in ground effect inside the vortex region.
Request. Ask for a longer interval - for example, request vectors for spacing or a 360° - or accept a landing clearance only if you can hold the spacing. Refuse the tighter interval; the turboprop behind is not your problem to solve with wake-vortex exposure. There is no shame in saying 'unable tighter spacing, we need two minutes'.
Decay is not guaranteed at light wind, so time and distance are the only reliable mitigations.
3. At 200 ft agl you feel a sharp buffet and the aircraft rolls rapidly to the right. What is happening, and what do you do?
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What is happening. A wake-vortex encounter. The roll rate from a vortex core can exceed full aileron authority, which is why the roll feels uncontrollable rather than merely strong. The buffet is the turbulent core passing over the wing and tail.
What to do.
- Apply smooth, full aileron against the roll and hold it; do not fight it with rudder or by snatching the controls.
- Maintain pitch attitude and do not pull - an involuntary pull at this height, at this speed, is how an encounter becomes a stall or a ground impact.
- Go around. At 200 ft with an active vortex roll, continuing to land is not a decision worth defending. Apply go-around power, establish a positive climb, and fly clear of the flight path - laterally, towards the upwind side if the geometry allows.
- Report it to the tower so the next aircraft gets the spacing.
Accept the altitude loss the encounter causes; do not trade airspeed for height to recover it.