decipher ATIS

[clayton4115 56]

9 hours ago, Farlis said:

Probably not. 

The METAR is missing visibility information, but considering that the temperature and dewpoint readings point to fog, that means that the top layer of the fog is at 1669ft and you won't be seeing anything below that layer. Most certainly not the 2.3 KM's required for the approach.

 

why is it giving it in Kms and not NMs ?

[Prpn 366]

7 hours ago, clayton4115 said:

 

why is it giving it in Kms and not NMs ?

Because most of the world uses the metric system/SI units wherever possible. So runway length and visibility will be in meters and directly relatable, for example in the case of low visibility takeoff and RVR. 

It is slightly sad we still deal with a mix of all kinds of units in aviation, though ICAO has been striving for metric/SI units for decades. A very, very slow moving change to SI is being made, even in the US.

[Flyfaster_MTN002 412]

On 7/5/2021 at 3:27 PM, clayton4115 said:

Hi

 

I am trying to decipher this but get confused with the altitudes

 

YPKS 052200Z AUTO 12004KT 9999 // OVC006 03/03 Q1023 RMK RF00.0/002.2

 

Is OVC006  = overcast at 600 feet or 60 feet?

download this its free:

https://apps.apple.com/us/app/aeroweather-lite/id288286079

[clayton4115 56]

3 hours ago, Prpn said:

Because most of the world uses the metric system/SI units wherever possible. So runway length and visibility will be in meters and directly relatable, for example in the case of low visibility takeoff and RVR. 

It is slightly sad we still deal with a mix of all kinds of units in aviation, though ICAO has been striving for metric/SI units for decades. A very, very slow moving change to SI is being made, even in the US.

 

so strange because everything in the flightdeck is in NM, the next waypoint, dme etc is all in NMs

[clayton4115 56]

3 hours ago, Flyfaster_MTN002 said:

download this its free:

https://apps.apple.com/us/app/aeroweather-lite/id288286079

sorry I don't use apple, I use andriod

[Prpn 366]

2 hours ago, clayton4115 said:

 

so strange because everything in the flightdeck is in NM, the next waypoint, dme etc is all in NMs

ICAO has a document called Annex 5 which is all about units used in aviation. Essentially, the NM is classified as an 'alternative unit' and the intention is to phase out its use over time. It is kind of a leftover of early aviation developments mainly in Britain and the US. Had the metric conversion act succeeded in the US, all the things you mentioned would have been in kilometers and meters.

[177B 730]

https://www.weather.gov/media/wrh/mesowest/metar_decode_key.pdf

[ark 1,290]

Also worth noting is wind direction in a METAR or TAF is the True direction (relative to True North), but in a spoken ATIS recording or when given from a control tower wind direction is Magnetic (relative to Magnetic North). This can be important when considering possible landing crosswinds using a METAR or TAF since runway directions are magnetic (to the nearest 10 degrees).

A general rule of thumb is 'written' wind direction is True, 'spoken' wind direction is Magnetic.

Al

Edited July 7, 2021 by ark