Aim To determine the minimum requirements for VFR pilots to plan flight to alternate aerodromes
Objectives 1.Define what an ‘alternate’ is 2.Specify minimum weather requirements for planning an alternate 3.List considerations which can be applied to obviate the planning of an alternate 4.Examples
1. Definitions AIP GEN 2.2 glossary: An alternate, is an alternative aerodrome which an aircraft may proceed when it becomes either impossible or inadvisable to proceed land at the destination aerodrome. Basically, a backup airport in case one cannot land at their intended destination Further details listed in AIP ENR 1.1 Paragraph 58 What is an ‘alternate’?
2. Legal requirements AIP ENR 1.1 para 58.2.12 For aeroplanes under day/night VFR, the minimum weather requirements for the provision of an alternate aerodrome is: No more than SCT (scattered) cloud below 1500ft AGL ceiling Visibility at least 8km Where (para 58.2.1a) FEW+FEW = SCT (scattered) FEW+SCT = BKN (broken) SCT+SCT = BKN or OVC (overcast) Minimum weather requirements
2. Legal requirements AIP ENR 1.1 para 58.2.1 In addition, an alternate must be planned if: a)Cloud more than SCT below minima (1500ft AGL) b)Visibility less than alternate minima (8km) c)Forecast of fog, mist, dust, haze, or any other visibility restrictions d)Wind greater than crosswind maximum (inclusive of gusts) And para 58.1.3, if a forecast is ‘provisional’, an alternate must be provided Should any of the above be forecast for a destination, an alternate must be planned! This does not mean the pilot must divert upon arrival – but he/she must at least plan or be ready for a diversion. Minimum weather requirements (cont.)
3. Considerations ENR 1.1 para 58.2.1 If within 50nm of a departure aerodrome the pilot need not provide an alternate, and this is subject to the following: Do we need an alternate?
3. Considerations ENR 1.1 para 58.2.4 An alternate is not required if the limiting conditions are intermittent (INTER) or temporary (TEMPO), AND, the pilot carries sufficient holding fuel until the poor weather passes. INTER = 30 minutes holding fuel TEMPO = 60 minutes holding fuel Para 58.2.6 Should there be multiple INTER/TEMPO’s, holding fuel may only be required for the most limiting factor. Holding Fuel
3. Considerations AIP ENR 58.2.7 Where forecasts include a FM (from) or BECMG (becoming) condition, and create weather conditions which would require an alternate, the following considerations will apply: Where a FM/BECMG is forecast to create conditions adverse to operations, that condition will become effective 30min before the FM/BECMG period. Where a FM/BECMG is forecast to create conditions better than expected, that condition will become effective 30min after the FM/BECMG period. Changing conditions
3. Considerations PARAFIELD (YPPF) TAF AMD YPPF 112304Z 1200/1212 04010KT 9999 LIGHT RAIN SCT040 BKN100 FM120800 04010KT 8000 LIGHT RAIN SCT020 BKN030 TAF is valid from 0000utc to 1200utc Forecast conditions are 10km visibility with scattered cloud at 4000ft FROM 0800utc the conditions are becoming worse with 8km visibility and cloud at 2000ft. For planning the pilot should expect this to occur 30min earlier at 0730utc. Changing conditions (cont.)
4. Examples PARAFIELD (YPPF) TAF AMD YPPF 112304Z 1200/1212 04010KT 9999 LIGHT RAIN SCT040 BKN100 FM120700 04010KT 7000 LIGHT RAIN SCT015 BKN030 Arrival for destination Parafield is 0500utc Answer: NO! Conditions FM 0700utc are not to be expected until 0630utc (30min buffer), and the ETA is 0500utc What is ETA was 0645utc? Answer: YES! Conditions FM0700utc are to be expected to commence at 0630utc (30min buffer), and the ETA 0645utc is after that. Are alternates required?
4. Examples EDINBURGH (YPED) TAF AMD YPED 112304Z 1200/1212 04010KT 9999 LIGHT RAIN SCT040 BKN100 FM120800 04010KT 8000 LIGHT RAIN SCT020 BKN030 INTER 1200/1208 5000 MODERATE RAIN SCT030 BKN040 Arrival for destination Edinburgh is 0400utc Answer: YES! There is INTER rain between 0000utc and 0800utc, and after applying 30min buffer this means rain can be expected between 2330utc & 0830utc The ETA is 0400utc – right in the middle! What if the pilot did not want to plan an alternate, is this ok? Answer: YES! So long as 30minutes holding fuel is carried. Are alternates required?
4. Examples ADELAIDE (YPAD) TAF AMD YPAD 112304Z 1200/1212 23010KT 9999 LIGHT RAIN SCT040 BKN100 INTER 1200/1208 5000 MODERATE RAIN SCT030 BKN040 TEMPO 1204/1210 3000 MODERATE RAIN BKN014 Arrival for destination Adelaide is 0600utc Answer: YES! Are alternates required? 0000utc---------------------------------0800utc 30min buffer--- 0830utc 2330utc---- 30min buffer 5km visibility 0400utc---------------------------------0800utc 30min buffer--- 1030utc 0330utc---- 30min buffer 3km, BKN 014 ETA 0600 What if the pilot did not want an alternate? Is this ok? Answer: YES! Carry 60min holding fuel (the most limiting/worst condition)