Information on meteorological events

Transmission of weather information

Meeting the president of the Aviation Transport Committee of the French Met Council and B777 TRI/TRE (Type Rating Instructor /Examiner) captain

What is your opinion about the role of ATC in the transmission of weather information?

Situation awareness with regard to the weather situation is essential when it comes to flight safety. It must be optimal and shared by all actors in the air transport chain, from cockpits to control towers. For aircrews, it is necessary to know the forecast met events along their route and the problems that might come along, to take the time to analyze them, know how to solve them and develop a strategy. This is TEM (Threat and Error Management). ATC is an essential player in this process, particularly in the real-time transmission of meteorological updated information, even if the crew has at its disposal elements obtained during the flight preparation (TEMSI, WINTEM, TAF, METAR, and additional elements provided by dispatch if the airline has one).

DSNA’s answers: our tools providing general met information:
Météo France (the French Met service provider) produces 2 daily en route weather forecasts for the 5 ACC in France. They each cover a 12-hour period. Each release is divided into 2 parts and includes 6 hour forecast charts (significant phenomena, winds). They also provide a focus on the airspace managed by each of the five en route centres. In addition to these met releases, Météo-France issues SIGMET * if necessary.

*A SIGMET (SIGnificant METeorological Information) is a message for in flight aircraft reporting significant meteorological phenomena (turbulence, thunderstorms, icing, etc.) that are observed and / or expected and that can affect flight safety. SIGMET must be relayed by ATC to all aircraft about to be concerned by this weather advisory.

ATC also has access to regularly updated Météo France weather information to help ensure flight information service to customers and airspace users. These meteorological services and products are concentrated and accessible on a web site for either en route , or approach control on each major platform.

Thunderstorm activity

What essential information do you expect from ATC, in the en-route phase?

Information on storm cells is important, especially when on the arrival trajectory. They will affect the conduct of the flight and possibly joining the final destination. Anticipation is essential in this situation (fuel load management, anticipation in changing diversion airport). Crews want to avoid bottleneck situations. Real-time updated information from ATC contributes to a better anticipation by crews in safely managing thunderstorm events.

DSNA’s answers: tools for storm cells’ information:
ASPOC is the tool used by French ATC to get information on convective areas that can be dangerous for aircraft (risks of lightning, windshear, hail, etc.). It identifies the clouds likely to influence the evolutions of aircraft and gives a representation of the convective activity based on observed data. The images provided are generated by Météo-France. ASPOC provides a representation of an expected 30 minute trajectory of the convective cells. The image is updated every 5 minutes.

For DSNA main approaches, this image is available on the control working position, on a dedicated screen. For DSNA 5 ACC, the ASPOC information is available on the control room supervisor’s position.

The image refresh rate and the error rate of the trajectory extrapolations do not allow use for the provision of ATC service. The image cannot be used to provide radar guidance for avoiding convective cell activity.

ASPOC allows the controller to anticipate the progress of the convective cells, to evaluate its possible impact on arrival and departure trajectories, to anticipate the possible avoidance pattern of aircraft, and to improve the coordination needed air traffic flow management.

The future, ASPOC 3D
This new tool provides an estimate of the vertical extension of convective cells’ developments. Deployment in DSNA ACCs is already scheduled.
In addition, Météo France is planning to provide an extrapolation of the convective cells over one hour, and eventually, information on the position of the storm cells in 3 hour time.

Clear air turbulence (cat)

Aircrews expect CAT area’s forecast including minimum and maximum altitude of the area.
The aircraft will be able to anticipate a change in its horizontal and / or vertical trajectory, and warn the cabin beforehand.

DSNA’s answers: our tools for Clear Air Turbulence reports:
The SIGMET is the message describing severe turbulence areas. This "SEV TURB" SIGMET is the reference information that the controller must relay to the concerned crews.

The en route centers also have at their disposal CAT forecast charts issued for 7 different flight levels. These charts are updated every 6 hours. ATC can see the expected winds at a selected level and, depending on the forecast, colored areas indicating the possibility of CAT areas and their associated severity.

Besides, all pilot reports transmitted by aircrews on the frequency will be relayed by ATC to all concerned aircraft, as well as to Météo France

Tail wind on final and wind shear

What essential information do you expect from ATC, in the approach/landing phase?

Tail wind on final and wind shear are serious threats to flight safety. Aircrews expect ATC to systematically report these events.

DSNA’s answers: our means and tools at disposal for tail wind information

“Tail wind can be referred to as the wind blowing in the same direction as the course of an aircraft. When landing, crews will expect head winds, particularly on final, as a means to easily obtain compatible ground speed to safely land. However, in some cases, the surface wind and the wind on final can somehow differ, showing the importance for flight crews to obtain this information. In the case of tail wind on approach, the increased groundspeed will necessitate an increased rate of descent. Failure to compensate for these factors could easily result in an unstable approach. Informing air crews about tail wind on final thus contributes to flight safety since they would not be surprised in case of tail wind and would be able to prepare the aircraft accordingly.

French ATCOs naturally and systematically complete their landing clearances with the surface wind information at their disposal. They will also inform aircrews if they have had previous Pilot REPorts about tail wind on final, strength and altitude.

The French MET service provider, Météo France, has developed an airport extranet notably containing a service providing this tail wind information for 4 different altitudes: 1000ft, 3000ft, 5000ft and 10000ft. DSNA is currently working in cooperation with Météo France in order to allow ATC to have access to this information directly on the control working position. When the equipment and the process will be in place, and above a defined and agreed threshold, the information will be transmitted to aircrews either via ATC reports or onto the ATIS.”

DSNA’s answers: our means and tools at disposal for wind shear information

ATC in France does not have a prediction of the wind shear phenomena. This type of event can only be relayed by ATC to concerned aircrews as part of Flight Information Service if a previous pilot report had been transmitted on the frequency.

In the near future, a LIDAR radar is expected to be installed on the Nice airfield, particularly subject to wind shear events. This radar will deliver additional data to the ones produced by the existing Met radar on the platform. In the long term, Nice Air Traffic Services will have a complete observation/forecast of wind shear phenomena for the benefit of aircrews.

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