HD21 turbulence forecast
Hokkaido International Airlines · Tokyo (HND) to Sapporo (CTS)
Next departure at its usual time · Sun 8 Nov, 11:15 Tokyo time
This date's schedule isn't confirmed yet. This is the air HD21 flies through if it leaves at its usual time.
A gentle ride. A few light ripples at most, the kind that barely move your drink.
- Bumpiest stretch
- Light
- Flight time
- 1h 30m
- Distance
- 820 km
- Cruise altitude
- 33,000 ft
- Weather models
- 3 blended
- Model agreement
- Medium
- Aircraft
- BOEING 767-300
Bumpiness along the flight
Takeoff on the left, landing on the right. The higher the line, the bumpier the air the forecast expects at that moment.
Where, and why
The flight split into stretches: how bumpy each is forecast to be, and what causes it.
HND · Take off0m – 5mLight
Jet-stream wind shear
Where fast air slides over slower air, usually at the edge of the jet stream, the boundary ripples like a flag. It's the most common kind of turbulence, and it's on the crew's charts before departure. When they meet it, they slow to a set turbulence speed and ride it out.
The first minutes are flown through the lowest, liveliest air. Sun-warmed ground sends up thermals and wind bends around hills, so a bump or two while climbing is normal. It fades as the aircraft climbs into the smoother air above.
Cruise5m – 14mSmooth
Nothing significant forecast here.
At cruise the air is thin and cold, and most of it is calm. The bumps up here come from the jet stream, a band of fast wind whose edges stir the air, or from waves set off by mountains far below. This forecast shows where those edges are.
Cruise14m – 1h 30mLight
Mountain waves
Wind blowing over a mountain range makes waves in the air downstream, the way water ripples over rocks in a stream, and those waves can reach cruising height. They are forecast from the same wind and terrain data used here, so the crew knows where they are before departure.
At cruise the air is thin and cold, and most of it is calm. The bumps up here come from the jet stream, a band of fast wind whose edges stir the air, or from waves set off by mountains far below. This forecast shows where those edges are.
This forecast changes. FlyBud tells you when.
A new weather model run lands every few hours. Add HD21 in FlyBud and you get the full turbulence map along your route, a push when the forecast for your flight changes, live tracking and your flight on the lock screen.
The aircraft
What HD21 is flown with, and how it handles bumpy air.
BOEING 767-300
Bigger and heavier aircraft are moved less by the same patch of air, and every airliner is designed for much stronger turbulence than it will meet.
The airline
Hokkaido International Airlines
Hokkaido International Airlines operates HD21.
The route
Tokyo (HND) → Sapporo (CTS)
- Distance
- 820 km
- Flight time
- 1h 30m
- Usual departure
- 11:15 local
- Usual arrival
- 12:45 local
What each level feels like
- Smooth
- Calm air. Nothing to notice beyond the hum of the engines.
- Light
- Gentle ripples and the odd dip. Drinks stay put, and walking to the toilet is fine.
- Moderate
- Clear bumps. Drinks may slosh and the belt sign comes on. Uncomfortable, but the pilots stay in full control.
- Severe
- Strong jolts, and loose items can move. This is rare, and it's why the belt sign exists. Crews slow down and change altitude to get out of it.
How this forecast is made
The planned route is sampled from gate to gate at the altitude the aircraft flies, through 3 independent global weather models, and corrected with turbulence reports radioed in by pilots in the last few hours. Each new model run replaces the forecast; nothing here is a guess from the airline's history.
The weather models behind this forecast mostly agree; the bumpy patches may shift a little.
Planned route · timing and conditions may change.
Why turbulence isn't dangerous
Aircraft are designed for much worse.
Airliners are tested to loads well beyond anything turbulence produces. The wings are meant to flex, so seeing them move is normal.
Crews know where it is.
Your crew has forecasts like this one, live reports from other pilots and their own weather radar, and they change altitude to stay out of bumpy air.
Keep your belt on.
Almost all turbulence injuries happen to people who are standing or not buckled in. Seated with your belt on, turbulence is uncomfortable but not dangerous.
Questions about HD21
Will HD21 be bumpy?
For the flight on Sun 8 Nov: A gentle ride. A few light ripples at most, the kind that barely move your drink. The forecast is replaced with every new weather model run, so check back closer to departure.
How long is HD21?
About 1h 30m gate to gate from Tokyo to Sapporo, a distance of about 820 km.
What time does HD21 leave?
HD21 usually departs Tokyo at 11:15 local time and arrives in Sapporo at 12:45 local time. Times change; the app tracks the live schedule.
Is turbulence dangerous on HD21?
Turbulence is uncomfortable, not dangerous to the aircraft. Airliners are certified for loads far beyond anything turbulence produces, and crews plan around the bumpy patches with the same kind of forecast as this one. Injuries are almost always to people who were standing or unbuckled, so keep your seatbelt fastened whenever you're seated.
How accurate is this turbulence forecast?
It is a forecast, so it is best within a day or so of departure and improves with every model run. The bumpy patches it finds are usually in the right place, but their timing can shift by a few minutes and the crew may change altitude to avoid them, so the ride you get is often smoother than the forecast.
Fly HD21 knowing what's ahead
The turbulence forecast for your exact flight, live tracking, delay alerts and arrival weather. Built for people who'd rather know.