The importance of weather for pilots: A blog for World Meteorological Day
We’re British, we talk about the weather.
It’s a conversation opener and it affects all of us in some smaller or larger way and we love to chat about the effect that it has had on our day !
Whether you are a fisherman, agricultural worker, oil rig employee or just deciding whether to mow the grass or take your umbrella to work in case it rains later, we are always interested in the weather forecast. In the U.K. there are many sources of weather information on TV, online, Apps on your phone. It is very easy to find an hour by hour forecast for either the day or the next 2 weeks.
For any Pilot, the weather can either make your day very straightforward or could introduce complications that can make your job a lot trickier.
The importance of weather information is reinforced from the day you start your training. A weather briefing every flying day plus hours of tuition by the Ground School Tutors and finally Examinations before you can be issued with your Licence.
A common saying amongst pilots is that you use ‘ Your superior knowledge to avoid having to use your superior skill’. This starts when the pilots report to work and are provided with a flight plan detailing the routing and fuel usage and a Briefing ,which covers everything from the passenger load, airport and airspace information, aircraft status and weather information.
Weather effect on operations
‹This weather information has to be examined to decide how it’s going to impact the day’s operation. If it’s a lovely, quiet high pressure day with beautiful weather at both departure airfield and destination then the answer is probably not a lot. But we still have to examine if a jet stream aloft will cause turbulence at certain flight levels. How will that affect any cabin service ? What if we have to cruise lower or higher than planned and thus use more fuel than the flight plan allowance ? What if the warm weather at destination turns hotter causing stronger gusty winds, a build up of cloud that leads to a thunderstorm at the time of arrival. This could potentially lead to a diversion to an airfield with better weather which then affects flight/cabin crew hours as the subsequent disruption has knock-on effects. However, the flight crew will have used their superior knowledge to anticipate potential threats to the operation and put a plan in place to mitigate.
That same flight in the Winter will pose different issues as the high pressure means very low temperatures at night causing Hoar frost covered wings or Rime icing that attaches itself to the engine fan or turbine blades which would require removal before flight. The slippery ground conditions will cause changes to the aircraft take-off and landing performance that has to be calculated by the flight crew. Any allowable defiencies on the aircraft then have to be reviewed to see if they can still be carried with these Met conditions. For example, one of the many brake units may have been deactivated until spares become available but this may not be allowable on slippery runways. There will be ground handling difficulties for the Refuellers, Baggage loaders and Engineers.
Inevitably, this means the ground operation slows as safety takes precedence. Instead of the frosty conditions it could become foggy which could drop the visibility below the limits for safe take-off or landing. Even if operations continue, it will be at a much reduced rate to maintain the level of safety required. In all cases the final responsibility for the safety of the flight rests with the Captain and decisions will have to made about fuel carriage, passenger handling and flight time limitations.
Longhaul flight crews are very familiar with the climatology of the Earth and the different seasons in both hemispheres. They’ll know that the flights across the North Atlantic in the Winter between Europe and North America will throw up a number of challenges as a succession of Low pressure areas bring strong winds, heavy rain and snow. At cruising levels there will be clear air or convective turbulence caused by the rapid pressure , temperature and wind changes. The flight crew workload increases as they have to use the forecast charts and their own experience to try and avoid or at least mitigate the passenger comfort levels knowing that any severe turbulence encounter will soon appear on YouTube! They will also be keeping an eye on en-route airfield weather should they have to divert for aircraft technical reasons or passenger illness. But these airfields may have extremely cold weather conditions which brings further challenges as the altitude information provided by the instruments has to be amended. Crosswind limitations have to be considered as they become more restrictive. Runway widths may be compromised by snowbanks. Passengers on a normal flight would not be clothed to cope with exposure to these conditions.
Alternatively, the Flight Crews will welcome the rostered flight to the Carribean Islands in the Winter as they know that the weather will be settled, warm with the balmy trade winds blowing. The hurricane season along with the severe and disruptive thunderstorms will have passed and the crew will be less concerned about any possible weather issues.
Accessing the data
A lot of weather information and models is available to pilots although the individual airline may prefer to use one supplier. The warming of the atmosphere is causing more extreme weather events around the globe and pilots will have to be aware of the consequences. The warm atmosphere can hold more water moisture or ice. This ice has been proven to damage aircraft engines over an extended period of time so pilots need to be provided with weather information to avaoid these regions to reduce costs.
Work is ongoing with aircraft contrail management which will help in reducing some of this warming effect. This can be incorporated at the flight planning stage but pilots will need to know why a certain flight profile has been selected and the importance of keeping to the plan. data is supplied from satellites, weather balloons and aircraft and analysed by computer and professionals forecasters before turning up at the pilot briefing. But it is still up to the flight crew on the day to use their knowledge to interpret that information and decide how it’s going to affect their flight and plan accordingly.