The Weather Checklist for Pilots - Part 1

Weather - pilots best friend cum troubler in chief. All books on Piloting mention about checking the weather at both source and destination. If we look at many aircraft checklists too, it has a weather checked - item among a host of pre-flight checks. I was trying to demystify the above single item check on the checklist and thought about coming up with a detailed sub checklist for weather to be completed by all pilots. Let me elaborate my efforts in this direction:

1. Visibility:-  Whether you are in Visual Meteorology Conditions(VMC) or Instrument Meteorology Conditions(IMC), its essential to know the visibility because without it, taxying cannot be started. To know visibility, one must check METAR report or obtain it from ATIS. Future trends can be obtained from TAF. However, old school method of knowing visibility is to check for a known distant marker object from a predetermined position to get a fair idea. Having said that,  let me narrate an incident that I faced during my flight training days. We used to have a marker and it was clearly visible, but our Aerodrome METAR had a lower report(Controlled AD) and we used to go ballistic about it. However, during one of my pre-dusk arrival from long cross country flight during hazy weather day, we couldn’t clearly see the end of downwind marker(we used to have markers on ground in circuits) before joining the downwind. Upon landing, the fixed visibility marker was clearly visible. This was ample proof that old school ways, though serving the purpose, are not to be relied on 100% as they are indicative of straight line visibility whilst what is needed for Pilot is slant visibility and is accurately obtained from METAR/TAF/ATIS.

2. Winds:- Winds are essential component as they are the basis of flight. Wind speed and direction can be obtained by looking at the windsock at the runway(conventional) or from METAR/ATIS and TAF(future trends). It helps determine the runway orientation to use and also the drifts one can expect in flight.

3. Temperatures: Temperatures are a good indicator for engine performance and flight conditions. Temperature and dew point are obtained from METAR/ATIS. TAF does not include any temperatures. ARFOR could be used to determine enroute temperatures at higher flight levels. From temperature and dewpoint, we can deduce the cloud base height to help us determine safe cruising altitude to opt for. It also gives clues on icing conditions that one could encounter.

4. Pressure: Its essential measure to set in our aircrafts altimeter before start. Pressure can be obtained from METAR/ATIS. All heights/altitudes/FLs are dependent on the correct setting made by noting the appropriate pressure(Qfe/Qnh/Qne). Besides, it can also be an indicator of aircraft performance.

5. Clouds: The height and amount of clouds can be obtained to understand the climb profile and cruise altitude to opt for and also any deviations or infact NoGO/NoTakeOff conditions can be determined. During my training days, I used to wonder if the heights were as per name say AGL or altitudes or FL - in this regard I used to try to roughly measure the cloud heights while flying below it and tried to be oversmart or overdumb in the process. But in reality, the clouds are mathematical deductions based on angle subtended at the point of observation and instruments used(ceilograph) - hence are to be treated as heights(AGL).

6. Extra weather phenomenon: Weather is not constant and the predicted changes can be obtained mainly from TAF with indicators like FM/TEMPO/BECMG/INTER/PROB etc. These must be carefully assessed and Flight/NoFlight can be determined.

7. Weather Images: Satellite weather images of current and expected trend images should be checked. These can be obtained from your Local Weather Services Agency or could be obtained from viewing the images in Newspapers/News TV channels. These are indicative of strong weather conditions that are likely to be encountered.

After gathering above data, I have come up with formulating a checklist which follows a flow that could be followed similar to an airplane checklist coming up in part-2 of this blog series.

Notes:

1. All the above weather information represented is based on information I used to gather for my flights during my training days(SE & ME aircrafts).

2. Airline Pilots/other pilots could have more information at hand in the briefing documents received - I have no information regarding those - request readers to pitch in with their views to enhance the above effort to come up with the checklist or if already any such checklists exist, please do share if allowed to.