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Weather Planning

One of the difficulties I have found with VFR flying has been assessing the weather forecasts, and deciding whether or not I am wise to embark on a journey. "Is the weather good enough to go?" is a very difficult question to answer since it relies on a definition of "good enough". With IMC and now also VFR flying I have instead started to attempt my weather planning based on known limitations, and to ask myself "is the weather bad enough not to go?" This is a much easier question to answer, since there are all sorts of circumstances when this might be the case. If it bad enough, then I do not go - it's as simple as that. If there are no reasons why I should not go then, providing alternates are planned, and fallback options decided, I will go.

It goes like this: assess the known limitations on pilot, current and forecast weather and airframe. Then compare these with conditions likely to be encountered en-route. Imagine a typical flight for me from Newcastle to Fairoaks.


1) Pilot

Limitation Example
a) Licence Privileges - I may not fly IFR or VFR in Class A airspace. In that case what is the minimum in-flight visibility I need when SVFR in Heathrow's CTR? At what heights am I going to need to fly to avoid Airways and the TMAs?
b) Experience Have I flown SVFR in Class A airspace before? Have I been to Fairoaks before, and I am I happy with the visual approach and likely altitude limitation on SVFR transit through the Heathrow CTR.
c) “Comfort” and confidence level If the answer to b) above is "no", am I happy to do this on my own the first time? Would it be better to take a friend?

2) Weather

Limitation Example
a) Wind How will the wind affect my flight planning? Can I leave before the club is open to get to my meeting on time? How will I manage this? Are there a crosswind, or severe gusts forecast for take off or landing?
b) Turbulence Is Turbulence forecast? If I have no autopilot, do I want to spend 2 hours stuck in bumpy Cumulus? Is my plane equipped with Autopilot to help me in this situation? And what is my maximum manoeuvring speed?
c) Icing level What is the forecast icing level? Do I need to stay below it? How will this affect sector safety altitudes? Can I get into clear air above the cloud without infringing Class A or other airspace, and get down again? If the freezing level is lower than forecast can I get down and stay above Sector Safety Altitude?
d) Visibility Will there be enough visibility to take-off and land safely? Will I be able to get into Heathrow's CTR under an SVFR clearance?
e) Precipitation Is rain, snow or hail forecast? How would this affect the flight?
f) Frontal Activity Where are they, where are they forecast to be, and what effect will they have? Will one be right over my destination when I arrive. How active is that occlusion? If I fly from a cold sector to a warm wet one will it dunpo freezing rain all over me?
g) Cb activity Are thunderstorms forecast? Will they be isolated and avoidable, or embedded and invisible?

3) Airframe

Limitation Example
a) Equipment Given the availability of radio aids en-route, is my plane equipped with all the necessary radios? Are they working? Does the plane I fly have a 2nd altimeter? Is there an autopilot and does the weather en-route suggest I might be more comfortable with one? Do I have a stormscope to find those embedded Cbs?
b) Service Ceiling How does my preferred cruising altitude match up with aeroplane performance? At what altitude will the plane perform best, and how does this match up with the weather forecast?
c) De-icing Is my plane de-iced in some way? And is it cleared for flight into "known icing?" If not how will this affect my plan? See 2c) above.
d) Weight, Balance and Fuel Does the distance I am planning to fly, with my passengers and baggage allow a proper amount of fuel, allowing for winds en-route, ATC delays and a good reserve? Will the plane be in balance at the beginning and the end of the flight?
e) Number of engines Am I personally comfortable with single engine night-time IFR? What if I am planning to fly over the Channel or to Ireland. Do I want to risk flying in IMC over cloud covered hills? Does this change my risk assessment?

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