Open Questions in Aviation Weather Service Provision

1. Open Questions in Aviation Weather Service Provision • Considerable Progress in meteorological Science • Advances in Avionics and airframe design • Improvements in observing technology • BUT : Information to Pilots, ATC/ATM, Operations Control still based on 1950es style telegraph codes

2. OPMET Information • METAR and TAF for international distribution • - valid for Terminal Aerodrome and 5 nm around • - mix of automated and manual observations • - half-hourly update rate for METAR, 3-hourly for TAF (Europe) • - TREND ICAO Standard, but several states are filing differences for cost reasons • - recent improvement to code to allow for sharper temporal resolution not yet universally applied by states • - lack of resolution in critical situations (RVR TREND not available, minimum ceiling in code 100ft, CAT IIIb below that value) • - fundamental difficulty in convective predictions for „strategic planning“-time frame of 2-6 hours

3. RVR-Tendency

4. Gap Analysis • Time Scale 2-6 hours: • - Kinematic extrapolation ineffective for short-lived phenomena • - Model forecasts suffering from inadequate assimilation of new data types (WXR, Satellite cloud top temps, soil properties) • - Very high resolution, explicit models „hyperactive“, i.e. pick up and amplify both signal and noise (realistic moisture convergence vs. Stochastic gravity wave activity) • - Multi-model, short-range ensembles promising, but still in infancy • - Interaction with topography statistically significant, dynamically difficult to model

5. Operational weather dependence • Reduced weather minima for individual aircraft reduce exposure to „average“ weather events • Terminal Capacity reduction depending on local / national / airline regulations • Critical thresholds sometimes not well communicated and trained • Very high forecast quality and reliability needed to base critical decisions • Quality control and verification needs to be user-specific, i.e. using flexible thresholds • For economic optimisation probability densitiy required • Highest „academic“ quality not necessarily translates into operational savings • Co-operative effort needed to determine weather impact depending on atmospheric parameters , aviation technology and regulations

6. Value-added products • With increasing traffic density, standard ICAO products not sufficient for optimised weather planning • Commercial opening for additional products • Temptation to overstate capabilities and understate problems, intransparent methodology in competitive environment • Labour-intensive services difficult to finance, automated products require in-depth user training , accompanying quality control and regular consultation • Uniformity of standards unlikely in a commercially driven environment unless WMO, ICAO and national Met Authorities are involved from the start • ISO certification helpful, but no guarantee for excellence of contents, only adherence to procedures is checked

7. Early Identification of Weather Conflict Situations • Safety: • - Derivation of probability density functions for Meta-Impact-Variables • - Matching of 4-dimensional PDF of Meta-Impact variables with a/c vulnerability profiles and 4-dimensional projected trajectories • - Resulting in identification of „hot spots“ in 4-dimensional continuum

8. Early Identification of Weather Conflict Situations-cont. • Efficiency: • - Extension of vulnerability concept to infrastructure (airports, airways, fleets) • - Determine critical thresholds • -Derive probability density for capacity impacting meta-variables • -Match with relative load (% of max capacity) for each part of infrastructure for time projections • Resulting „hot spots“ for delays/reroutings/canx

9. Avoidance and mitigation • Avoidance: • - Strategic planning by CFMU, Ops control, ATM to circumnavigate safety-“hot spots“ • Reduce load around efficiency „hot spots“ by offering alternatives • Increase handling capacity (divide sectors, staffing levels etc) Mitigation: Prepare short-term alternatives Anticipate avoidance manoevres Increase awareness before „hot spot“ is entered