JL42 turbulence forecast
Japan Airlines · London (LHR) to Tokyo (HND)
Next departure at its usual time · Fri 6 Nov, 08:50 London time
This date's schedule isn't confirmed yet. This is the air JL42 flies through if it leaves at its usual time.
Smooth most of the way, with some light bumps after takeoff. Barely moves your drink.
- Bumpiest stretch
- Light
- Flight time
- 13h 50m
- Distance
- 9,601 km
- Cruise altitude
- 37,000 ft
- Weather models
- 3 blended
- Model agreement
- High
- Aircraft
- Airbus A350
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 – 2h 55mSmooth
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.
Cruise2h 55m – 3h 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.
Cruise3h 45m – 12h 10mSmooth
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.
Cruise12h 10m – 13h 50mLight
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.
Thunderstorms near the route
Around 13h 34m into the flight the forecast has a thunderstorm 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 JL42 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.
Flight status
The latest JL42 flight on our records, as the airline last reported it.
Last update 7 days ago
Gate changes, delays and the baggage belt, pushed to your phone as they happen.
The aircraft
What JL42 is flown with, and how it handles bumpy air.
Airbus A350-1000
- Type code
- A35K
- Seats on this flight
- 239
- First flew
- 2013
- In service since
- 2015
- Economy seating
- 3-3-3
- Engines
- 2
- Range
- 15,750 km
- Cabin pressure equal to
- 6,000 ft
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
Japan Airlines
- Flying since
- 1951
- Alliance
- Oneworld
- Hubs
- Tokyo Haneda, Tokyo Narita
- Country
- Japan
The route
London (LHR) → Tokyo (HND)
- Distance
- 9,601 km
- Flight time
- 13h 50m
- Usual departure
- 08:50 local
- Usual arrival
- 07:40 local
Recent JL42 flights
The forecast each flight carried, and how it ran.
| Date | Aircraft | Forecast | How it ran |
|---|---|---|---|
| Thu 29 Oct | A350 | Moderate | 21 min early |
| Tue 27 Oct | A350 | Moderate | 38 min early |
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 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 JL42
Will JL42 be bumpy?
For the flight on Fri 6 Nov: Smooth most of the way, with some light bumps after takeoff. Barely moves your drink. The forecast is replaced with every new weather model run, so check back closer to departure.
What plane flies JL42?
Recently JL42 has been flown with: Airbus A350. Airlines can swap the aircraft until shortly before departure.
How long is JL42?
About 13h 50m gate to gate from London to Tokyo, a distance of about 9,601 km.
What time does JL42 leave?
JL42 usually departs London at 08:50 local time and arrives in Tokyo at 07:40 local time. Times change; the app tracks the live schedule.
Is turbulence dangerous on JL42?
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 JL42 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.