Effective: SPECI ALERTING

Transcription

1 AUSTRALIA AERONAUTICAL INFORMATION SERVICE AIRSERVICES AUSTRALIA GPO BOX 367, CANBERRA ACT 2601 Phone: Effective: AERONAUTICAL INFORMATION CIRCULAR (AIC) AIRAC H 34/ UTC 1. INTRODUCTION SPECI ALERTING 1.1 Currently, ATC only provide pilots with SPECI weather reports for non-towered aerodromes with no automatic broadcast facility. 1.2 From 8 November 2018, ATC will change which SPECI information is provided at non-towered aerodromes. Non-towered aerodromes includes: a) Aerodromes without a tower service, and b) Aerodromes with a non-continuous tower service, outside the tower hours of operation. 1.3 The changes to SPECI dissemination will mean that pilots are provided with SPECI for all non-towered locations, but ATC will only provide reports that are useful for the safe conduct of the flight. This will increase the alerting value of SPECI information provided and reduce the amount of unnecessary information, frequency congestion and workload for both pilots and ATC. 1.4 The assessment and distribution of pertinent SPECI to ATC will be done automatically by a computerised filter. ATC will then disseminate the information to affected pilots. 2. WHAT WILL CHANGE 2.1 Selected SPECI reports will be provided by ATC for all non-towered aerodromes regardless of whether the information is available from an automatic broadcast station. 2.2 Selected SPECI will include reports that are both: a) Unforecast, where a TAF is available, and b) Considered significant

2 (AIC H34/18) Page 2 of ATC will not provide SPECI reports that are the same or better than forecast, even if the weather is poor. 2.4 In order to define the criteria for significance, a set of significance parameters have been developed with industry and include aspects such as wind, temperature and the cloud and visibility alternate minima applicable to the aerodrome. Where no TAF service is provided for an aerodrome, ATC will provide SPECI based only on the criteria for significance related to alternate minima and weather phenomena. The full set of parameters is available in Appendix ATC will not provide repeated SPECI information, i.e. reports with the same or very similar information that are issued within 15 minutes of the previously disseminated SPECI, will not be provided. 3. WHAT WILL NOT CHANGE 3.1 Pilots remain responsible for obtaining information necessary to make operational decisions. 3.2 ATC will disseminate the information in the same way as it is done now i.e. non-routine information will be directed to aircraft in continuous communications within one hour s flight time of the condition, and broadcast to those aircraft that are not in continuous communications. During high workload, ATC may still advise pilots to access information from an alternate frequency. 3.3 The dissemination of other non-routine MET products will remain the same, so pilots will continue to receive all applicable AMD TAF, TTF SPECI, ATIS changes, hazard alerts etc. 3.4 Information provided for Towered aerodromes will remain the same. 3.5 Pilots may continue to request the latest aerodrome weather information as they do now, and will still be able to access the latest data from the automatic broadcast station, where available. 3.6 The SPECI criteria listed at AIP GEN 3.5 sub-section 4.3 will still be used to issue an aerodrome weather report as a SPECI. 4. SELECTED SPECI SCENARIOS 4.1 The SPECI Alerting Filter is able to interpret complex TAFs, including INTER, TEMPO, FM, and BCMG, and also considers requirements such as the 30 minute buffers that are required to be applied by pilots to these types of conditions.

3 Page 3 of 4 (AIC H34/18) 4.2 Some examples of how the SPECI Alerting functionality will work are provided below: TAF SPECI ATC action TS, RA, BKN008 TS, RA, BKN008 Nil SPECI same as TAF TS, RA, BKN008 -RA, BKN006 Disseminate due to more than 4 OKTAS of cloud below the alternate minima and the cloud base is lower than forecast VIS 400M FG VIS 2000M TS Disseminate due to change in weather code Wind VRB05KT Wind 09010KT Nil wind is not significant until at least 15KT CAVOK VIS 8000M, BKN080 Nil Visibility and cloud are above the alternate minima No current TAF VIS 6000M Disseminate due to visibility below alternate minima No current TAF 09020G30KT Nil wind is not considered for initial assessment at non- TAF locations 4.3 When assessing a new SPECI, the filter will consider the last disseminated SPECI for 15 minutes. After this time, the filter will return to comparison only with the TAF or for non-taf locations, to the alternate minima and weather phenomena as per the table at 4.2. SPECI to SPECI comparison is done for all components of the SPECI. Some examples of the SPECI alerting functionality for subsequent SPECI are provided below:

4 (AIC H34/18) Page 4 of 4 TAF Last disseminated SPECI Second SPECI Within 15MIN ATC action for second SPECI Wind VRB05 Wind 09015KT Wind 10020KT Nil second SPECI is less than 10KT greater than the last disseminated SPECI TS, RA, BKN008 -RA, BKN006 TS, RA, BKN006 Nil second SPECI is the same as TAF and last disseminated SPECI CAVOK VIS 5000 BR VIS 4000 BR Disseminate due reduced visibility No current TAF 09020G26KT 5. FURTHER ADVICE 05020KT (Note - alternate conditions or significant weather must also exist) 5.1 Further advice may be obtained by contacting: Operational Standards - atsintegrity@airservicesaustralia.com 6. CANCELLATION 6.1 This AIC will remain current until 28 February DISTRIBUTION 7.1 Airservices Australia website only. Appendix 1. SPECI Significance Parameters. Disseminate due wind direction change of at least 30 degrees when the speed is 20KT or more

5 1. SPECI Significance Parameters Appendix 1 TO (AIC H34/18) The SPECI significance parameters have been determined to assess if a SPECI is reporting conditions that differ significantly from previous observations or forecasts. The elements that are used for significance assessment are presented below: SPECI component Wind Comparison is made with the highest value of the SPECI and TAF: Speed value where no gusts are forecast or Gust value QNH Temperature When the value is: 0 14KT 15KT or more Cloud All CB appears with cloud Difference in value NA - do not disseminate Speed is at least 10KT more than the TAF value and the last disseminated SPECI value 20KT or more Direction differs by 30 degrees or more from the TAF value and the last disseminated SPECI value At least 6 HPA more or less than the TAF value and the last disseminated SPECI value At least 5 C more or less than the TAF value and the last disseminated SPECI value If CB is not on the TAF or last SPECI No instrument At least 5 OKTAS of cloud below the LSALT for the final route segment plus 500FT; and Either there are more OKTAs of cloud; or the base of the lowest layer is less (i.e lower) than the TAF value and the last disseminated SPECI value

6 Cloud (cont.) Instrument Visibility Default value i.e. no instrument Instrument Other conditions Whenever the following conditions exist in the SPECI but do not exist on the TAF and the last SPECI 5 OKTAS or more of cloud below the highest alternate minimum cloud base; and Either there are more OKTAs of cloud; or the base of the lowest layer is less (i.e. lower) than the TAF value and the last disseminated SPECI value Less than 8KM; and Less than the TAF value and the last disseminated SPECI value Less than the highest alternate minimum visibility; and Less than the TAF value and the last disseminated SPECI value TS RA FG FC FU DU DS SA SS SN Thunderstorms Includes RETS Rain Includes RERA, RASH, +RA, FZRA Fog Includes BCFG, MIFG, PRFG Funnel cloud Smoke Dust or dust storms Sand or sand storms Snow