Speed bumps in the sky – turbulence explained

Published on 31st March 2017 at 9:47

Keeping lookout. Pilots monitor conditions ahead – including talking to other aircraft on the same route – to detect and avoid turbulence the best they can. But even in clear flying conditions, sudden wind changes can cause some unexpected bumps. Seat belts are always buckled up on the flight deck.

Turbulence is one of the most talked about elements of flying among passengers. But for cabin crew and pilots, it’s simply part  of the job and certainly not something to fear (provided you’re buckled up).

That said, it can be uncomfortable. And it’s a leading cause of spilt drinks in-flight. So, a lot of effort goes into minimising the amount of turbulence we encounter.

Here are some facts about turbulence and how we manage it, plus an interview with our Chief Technical Pilot, Alex Passerini, about what he has experienced in more than 20 years of flying.

What causes turbulence

There are three main causes of turbulence.

  • The most common is a sudden change in the wind direction and speed. (These combined forces are called ‘windshear’ and the impact on flying is called ‘clear air turbulence’). Aircraft can encounter a lot of sudden wind changes as they climb through the atmosphere to reach their cruising altitude (where the air is usually much smoother)  That’s why the seat belt sign typically stays on for several minutes after take-off – the Captain is waiting to reach smoother air higher up.

  (Pro tip: If you listen carefully as the aircraft climbs, you’ll be able to hear the wind noise around the aircraft increase. This is usually the aircraft   reaching a jetstream, which run like currents in the upper atmosphere.

  • Turbulence is also caused by a sudden change in air temperature, which often happens when flying through thick (so fluffy!) clouds.
  • The third cause is wake turbulence. Large jet aircraft (like the A380 or B747) disturb the air as they fly through it at close to the speed of sound – a bit like a large ships creating a wash behind them as they churn through the ocean. For this reason, air traffic controllers deliberately leave plenty of distance between large aircraft in particular. Wake turbulence does happen, but it’s very uncommon.

Planning a smooth flight. Pilots receive charts like this as part of their flight plan, giving them an indication of weather conditions en route. The white numbers in the black circles show the intensity of wind changes (or, shear rate) that create turbulence.

Reducing turbulence

There are a few ways we work to reduce turbulence, in the interests of giving you a more comfortable flight.

  • Weather reports as part of their pre-flight briefing, pilots receive a map from our Integrated Operations Centre on their iPad showing the weather along their planned route. This includes an indication of likely turbulence (measured as ‘shear rate’) on a scale of 0 to 15. The pilots will use this information to plot the smoothest path they can. Most of the time, numbers are between 3 and 6. Anything over 10 you’d probably tell your friends about. But the aircraft can deal with all of it. Otherwise, we wouldn’t be flying.
  • Other aircraft aircraft flying on the same route often radio each other about any rough spots of unexpected turbulence they’ve encountered, and what altitude they’ve gone to (up or down) to find smoother air. Air Traffic Controllers join in as well, helping to share information between aircraft.
  • Radar on board radar equipment in the nose of the aircraft scans ahead to show storms, allowing pilots to plan a course around them. This is particularly important on long haul flights, where weather conditions on the route will change over the 10+ hour journey you’re on.
  • New technology there are some exciting developments that will help reduce the bumps in the near future. Our 787s (arriving from October 2017) have ‘Smooth Ride Technology’, which uses flaps on the wings to detect and counteract turbulence. And wi-fi on our domestic flights will give our pilots real-time weather updates, so they can avoid rough air more effectively.

Nothing to fear

Aircraft are designed to deal with turbulence many times more severe than anything you would realistically encounter. For instance, you might notice the wings flex up and down when it gets bumpy but they are designed to bend much, much further. And you might hear some of the cabin fittings creak, but the structural integrity of the aircraft is engineered for all sorts of turbulence. The biggest risk from turbulence is being tossed around – so whenever your seated, we recommend having your seatbelt done up.

Watch Captain Passerini below as he explains more about turbulence.