Military airfield TAF abbreviations

[Matthew]

Here is a TAF for an Air Force base:

---
KSZL 151111 07012KT 8000 BR FEW005 BKN010 BKN080 OVC120 QNH2997INS
TEMPO 1114 BKN005
BECMG 1314 05010KT 8000 -RA BR SCT010 BKN030 OVC050 QNH2994INS
BECMG 1617 08012KT 8000 -RA BR SCT008 BKN025 OVC030 QNH2998INS
BECMG 1920 08012KT 6000 -RA BR BKN005 OVC010 QNH3004INS
BECMG 2223 VRB06KT 8000 BR SCT008 SCT040 OVC120 QNH3008INS
BECMG 0405 35007KT 8000 BR SCT120 SCT250 QNH3002INS T21/21Z T13/10Z

---

I've not been able to decypher the 'QNH' and 'INS'.

I've only seen these abbreviations on military facilities.

Thanks for any information,
Matt

 

[poadeleted20]

QNH is altimeter setting, and INS is "inches," as in "inches of mercury" -- note that you have to insert the decimal point. And as a side note, military TAF's give visibility in meters, not feet or miles, so "8000" here is 8 km, or about 5 statute miles (for a quick conversion, multiply km by 0.6 to get statute miles and 0.5 to get nm).

 

[Matthew]

Yeah, I was assuming the reference was to altimeter, but wasn't sure if the 'QNH' meant something in particular about it.

Thanks,
Matt

 

[EdFred]

http://en.wikipedia.org/wiki/QNH

Anyone notice the error in that article?

 

[Matthew]

Yup..

 

[poadeleted20]

Anyone notice the error in that article?

If you're referring to "pilots will usually use the more appropriate QFE for determining height while landing," that's not an error in the UK, where everyone except the USAF (and maybe US air carriers) uses QFE in the pattern and on the approach, and this definition was clearly (to those of us bilingual in both the Queen's English and the American version) provided by a Brit. This was a constant headache for us in 3rd Air Force when we did practice approaches at RAF bases, as we often had to beg for a QNH setting to go with our DoD approach charts.

 

[Matthew]

The thing I saw was another item that lost something in the translation - those darned unit conversions!

 

[EdFred]

If you're referring to "pilots will usually use the more appropriate QFE for determining height while landing," that's not an error in the UK, where everyone except the USAF (and maybe US air carriers) uses QFE in the pattern and on the approach, and this definition was clearly (to those of us bilingual in both the Queen's English and the American version) provided by a Brit. This was a constant headache for us in 3rd Air Force when we did practice approaches at RAF bases, as we often had to beg for a QNH setting to go with our DoD approach charts.

Actually I was referring to the altimeter reading in the "quote" at the very end.

10.13 inches?

 

[gismo]

Actually I was referring to the altimeter reading in the "quote" at the very end.

10.13 inches?

Must have been in the eye of a really bad hurricane. Actually as you probably guessed, they used the standard altimeter settting in millibars and called it inches. Probably because the writer was used to seeing altimeter settings in mb.

 

[Areeda]

Does anyone know the difference between qns and qnh?

I believe they both refer to sea level pressure but are calculated from local pressure readings using different formulas. I'm looking for the formulas they use.

thanks