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Feature Feature

Demand for easier access to aviation information on mobile and handheld devices has

driven the Met Office to redevelop its General Aviation products, which are accessible from their website. It has been listening to customers and as a result has updated its General Aviation Briefing Service using advances in technology to meet changing demand. A series of video guides have been created, which take users through the new navigation and content.

The Met Office is designated by the CAA to provide an authoritative source of regulated aviation briefing products and information. For many years the Met Office has provided these products through its General Aviation Briefing Service.

Darren Hardy, Senior Met Office Advisor, said, “We saw clear themes arising from our customer feedback, and acted upon them to ensure we changed things which were important to the community”.

Met Office Revised GA Web PlatformCommon sense, and the law, requires pilots to obtain all the necessary weather information in order to plan their flights safely. Making correct and timely decisions is important when keeping to flying schedules and maintaining safety and weather can be one of the greatest hazards to aviation. Darren Hardy and Linda Jennings describe how the Met Office has refined its online service to assist aviators.

Above: The balloonist’s first port of call, the synoptic chart, valid 1200 UTC on 8th April, 2016.

KEY CHANGESKey changes in the latest version of the General Aviation Briefing Service include:

• Global TAF and METAR search functionality

• More quick links on the home page• Clearer layout on the home page,

differentiating between balloon and general aviation content

• Improved printing functionality• Access to maps on a mobile phone

– meaning you can now access radar on your phone

• On the Premium version, as in the old version of the Briefing Service, we have added in upper winds and temperatures and the significant weather charts.

Linda Jennings, Met Office Senior Marketing Manager said, “This has been a big technological development for us, which came about following feedback from customers. The improved design makes pre-flight planning for pilots considerably easier.”

The Met Office advises all sectors of the industry – airlines, airports,

air traffic control and management, ground handling, airport construction and maintenance – to help the aviation industry increase safety and achieve operational efficiencies and cost savings.

The organisation will continue to monitor all customer feedback about the GA Briefing Service, which will inform and enable more lifecycle improvements

THE BRIEFING SERVICE FOR BALLOONISTSWeather briefings in advance of flying vary considerably; and a ‘top down’ approach is often taken. This means firstly considering the wider weather picture in general terms, and then reviewing the expected weather over the region you are hoping to fly in, before finally focusing on the weather at your site.

To illustrate this approach, let’s take the example of a balloonist who was planning to fly from Bristol at around 6pm on Friday 8th April, 2016. Does the weather forecast suggest that it is safe to fly?

Step 1 – What is the general weather situation over the UK?

Firstly, the synoptic chart needs to be checked. With a basic understanding of fronts and air masses, these charts can show a lot about the expected general conditions.

The chart (above) shows the synoptic situation over the UK at midday on Friday 8th. There are quite widely spaced isobars and a ridge of high pressure over most of the UK. High pressure is often an indicator of settled weather, and widely spaced isobars indicate light surface winds. A trough, identified by the solid line, lies to the east of Bristol. There is a frontal system approaching from the west – this will likely lead to deteriorating weather conditions, such as a lowering cloud base, strengthening wind and rain as the front approaches.

Above: Ballooning site specific forecast for Bristol, valid 1600–2100 UTC

Above: Whatever the forecast, pilots should always keep their eyes peeled for potential unexpected hazards!

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Feature FeatureStep 2 – The general forecast

Area forecasts such as the low level UK significant weather charts (often known as the F215) puts into words the synoptic conditions over areas of the country. These can provide a useful weather summary.

In the F215 chart (right) valid between 1400–2300 UTC on the 8th, Bristol is shown within ‘Zone C at 1800 UTC (7 pm local time)’. The weather in this zone was forecast to be generally fine, with good visibility and just an isolated risk of a shower. A patchy cloud base was forecast between 1500–3500ft.

Note, however, the front approaching from the west. The weather associated with this front is described in Zone B. This zone describes widespread rain with poorer visibility and a lower cloud base. The arrow on the map shows it is moving towards Bristol at 20kt, so will soon start to affect this area.

Also, take a look at the TAFs and METARs in the area. Whilst these are specific to an airport, TAFs are actively monitored by the Met Office and METARs are regularly updated by the airport. Both will provide useful additional information on the current and forecast conditions.

Step 3 – What’s the weather likely to do over Bristol itself?

Using weather forecasts for the local detail becomes increasingly important as take off approaches. While light winds are essential for balloon inflation, the forecast wind direction and speed at higher levels (500’, 1,000’ and 2,000’) will give the pilot flight planning information as to the area where a potential landing opportunity may be possible. The wind direction becomes all important at this point, and a 10 degree change in direction can be the difference between success and failure to the flight. With information about winds and temperatures between 500 and 2000ft, the Met Office’s site specific ballooning forecasts can help in the decision process.

Site specific ballooning forecasts for some 85 UK ballooning locations have been developed to provide finer detail on the weather conditions most relevant to balloonists. These forecasts are updated frequently and much of the detail is provided in hourly timesteps to

help balloonists fine tune their ‘weather windows’.

These forecasts include:a. site specific forecasts of:• Wind speed and direction at surface,

500ft, 1,000ft and 2,000ft• Air temperature at surface, 500ft,

1,000ft and 2,000ft • Thermal strength• Wind shear

b. area forecasts of:• Temperature inversions• Rotors• Lee waves• Sea breeze activity & • Outlook

The forecast issued for Bristol provides a summary of the weather conditions over the period of the planned flight.

From the ballooning forecast issued in the morning, at 1700 UTC (6pm local) the average wind speed between the surface and 2,000ft does not exceed 15kt. Some thermal activity at 2,000ft was forecast, but there was no risk of windshear, lee waves or temperature inversions. After 1800 UTC (7pm local), however, the forecast wind speed was set to increase as the front approaches.

Remember that the forecast warns of rain approaching. The map layers on the aviation website allow you to see the progress of rain and other weather,

so you can track when the rain or lower cloud may start to prevent your operation.

From the maps shown on the right, the forecast leading edge of the rain band was expected to be west of the Bristol area at 6pm.

So, was it safe to fly at 6pm on 8th April, 2016?

The Met Office asked Ian Chadwick, AOC Balloon Inspector & Training Inspector (Balloons), CAA, for his opinion. Ian commented: “It may not be the best idea to fly a balloon from Bristol given the particular circumstances detailed above.

My thought process included the following points, not all of which are directly connected to the Met Office ballooning forecast:

(a) It is early in the ballooning season, so I may have flown little in preceding months, so I am out of recent practice;

(b) The ground conditions might be questionable if we have had a wet winter or wet early spring. (This is important when considering vehicular access with the retrieve car and trailer in order to recover the landed hot air balloon).

(c) The surface wind is forecast to be gusting up to 17kt at 17:00Z (18:00 local) and I must be mindful of the Flight Manual limits. It is forecast

to drop by 18:00Z (19:00 local), but that would be too late to allow for an average flight time of one hour and to land prior to sunset. (The 30-minute period between sunset and the start of official night is to be used for emergency contingencies only.)

(d) Thermals are still moderate at 17:00Z, suggesting that the forecast gusting will certainly be present. Thermals become weak, but not nil, as the evening progresses.

(e) All ‘upper winds’ (500’, 1,000’ and 2,000’) are forecast to increase as the evening progresses, probably to coincide with the arrival of the forecast weather fronts.

(f) The existence of the trough prior to the proposed flight period will add to the instability and this in turn may lead to the expected evening adverse weather commencing slightly earlier.

One where the preference is to retire to the local pub, I think!”

Unsure of anything once you have briefed?

So, we all know that ballooning is at the mercy of the weather, but a good knowledge of how to make best use of the weather forecasts can give you a head start.

Telephone clarification from a forecaster is available on any part of the forecast that is unclear. This service is provided without cost on behalf of the CAA and – whilst it is not a substitute briefing service – it is designed to forecast understanding after the standard forecasts products, such as F215 or ballooning forecasts, have been checked. e.g., if you are unsure how to interpret the details from the forecast. You can call the Met Office Weather Desk on 01392 885680 or 0870 900 0100.

If you are unable to personally brief, or prefer to obtain a bespoke briefing from a meteorologist, another option is to utilise the Met Office’s ‘Talk To A Forecaster’ service (www.metoffice.gov.uk/services/talkfc), a commercial service that allows 24-hour access to forecasters.

Above: Model forecast cloud/precipitation combination layer, valid 1800 UTC.

Above: Forecast precipitation valid 1800 UTC.

WANT TO LEARN MORE ABOUT THE WEATHER CHARTS?

The Met Office regularly runs short training courses for general aviators. See: www.metoffice.gov.uk/training/aviation-training/general

Full details of the product features can be found here: www.metoffice.gov.uk/aviation/ga-briefing-services/premium-upgrade

The Met Office will be attending the Bristol Balloon Fiesta this year. Feel free to come and see us for a chat!

Above: UK low level chart, valid between 1400-2300 UTC on 8th April.

AND FINALLY...Forecasts outline the most likely conditions expected. However, the weather is complex and forecasts can change. Use as much information as you can, and contact the Met Office to clarify your understanding of the current weather situation, especially in potentially difficult situations. Remember, however, that the final decision to fly (or not) rests with you as the pilot-in-command!