BR27 turbulence forecast
EVA Air · San Francisco (SFO) to Taoyuan (TPE)
Next departure at its usual time · Fri 6 Nov, 23:30 San Francisco time
This date's schedule isn't confirmed yet. This is the air BR27 flies through if it leaves at its usual time.
Smooth or light most of the way, with some moderate bumps mid-flight. The belt sign will likely come on.
- Bumpiest stretch
- Moderate
- Flight time
- 14h 10m
- Distance
- 10,391 km
- Cruise altitude
- 37,000 ft
- Weather models
- 4 blended
- Model agreement
- High
- Aircraft
- BOEING 777-300ER
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.
Cruise0m – 1h 23mSmooth
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.
Cruise1h 23m – 2h 24mLight
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.
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.
Cruise2h 25m – 4h 11mSmooth
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.
Cruise4h 11m – 6h 57mLight
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.
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.
Cruise6h 57m – 7h 58mModerate
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.
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.
Cruise7h 58m – 10h 45mLight
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.
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.
Cruise10h 45m – 13h 17mModerate
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.
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.
Descent into Taoyuan13h 17m – 14h 10mSmooth
Nothing significant forecast here.
Coming down means flying back through the low, lively air near the ground: afternoon thermals, gusts around the airport. It is the busiest part of the flight for the crew, and the part they train for most.
Thunderstorms near the route
Between 1h 46m and 8h 36m into the flight the forecast has a few thunderstorms, some on the planned line itself.
The ride line can stay calm with storms nearby. It follows the planned track at cruise height, above most storm tops. Pilots don't fly through storms: the weather radar in the nose shows each one, and the rule is to stay at least 20 nautical miles (about 37 km) away. Usually that means a detour of a few minutes.
The closest of these is within the 20 nm the crew has to keep, so expect a small turn around it. The line on the map is the planned route; the real track will bend around the storm.
This forecast changes. FlyBud tells you when.
A new weather model run lands every few hours. Add BR27 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 BR27 is flown with, and how it handles bumpy air.
BOEING 777-300ER
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
EVA Air
- Flying since
- 1989
- Alliance
- Star Alliance
- Hubs
- Taipei Taoyuan
- Country
- Taiwan
The route
San Francisco (SFO) → Taoyuan (TPE)
- Distance
- 10,391 km
- Flight time
- 14h 10m
- Usual departure
- 23:30 local
- Usual arrival
- 05:40 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 4 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 independent weather models behind this forecast agree on this ride.
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 BR27
Will BR27 be bumpy?
For the flight on Fri 6 Nov: Smooth or light most of the way, with some moderate bumps mid-flight. The belt sign will likely come on. The forecast is replaced with every new weather model run, so check back closer to departure.
How long is BR27?
About 14h 10m gate to gate from San Francisco to Taoyuan, a distance of about 10,391 km.
What time does BR27 leave?
BR27 usually departs San Francisco at 23:30 local time and arrives in Taoyuan at 05:40 local time. Times change; the app tracks the live schedule.
Is turbulence dangerous on BR27?
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 BR27 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.