I should know this...

A150K

Well-Known Member
On NACO approach charts, there is a series of numbers in parentheses listed right next to the height above touchdown zone on each set of approach minimums (for example, the RNAV 33 into SAF lists HAT as 416 with (400-1) listed right next to it. What does this number represent? I've been scratching my head for the past 30 minutes trying to find an answer.
 
Doh! Found my answer in the chart legend. Figures...turns out it doesn't matter to civilian pilots hense the reason I didn't know it.
 
Actually, if you start flying internationally and use QFE operations, it does matter. Know as much as possible, and never stop learning.

Edit: I'm referring to Jepps and assume NACO's are the same. I haven't used gov't charts in going on 7 years...
 
It's also a good wag for comparing mins to reported/forecast ceilings without having to do any cyphering.
 
It's also a good wag for comparing mins to reported/forecast ceilings without having to do any cyphering.
That's what I don't get about people being afraid of QFE ops. It's simple.... Get altimeter setting, and guess what the altimeter reads when on the ground? Zero. I now get worried when I do "normal ops". Ok, American put one in the trees in BDL because they didn't use current settings during a major storm with massive pressure changes. Guess what, you can do that with QNH procedures also.

Other than pressurization items in the plane, I never have to worry about what field elevation is.
 
I think it's more keeping the three straight. QFE, QNH, QNE.
QFE= field elevation. QNE = never exceed (goes to the moon, above TL/TA). QNH = WTF altitude are we supposed to go to?

I really should be teaching QFE ops at SAV. Do you hear that, Gulfstream, and FSI? ;)
 
QFE = altimeter setting that would read zero at the field

QNE = 29.92

QNH = altimeter setting that will give you field elevation when on the field (normal altimeter setting here in the states)


QFE height above Field Elevation
QNE normal enroute
QNH normal height

How I kind of keep them straight.
 
QFE = altimeter setting that would read zero at the field

QNE = 1013

QNH = altimeter setting that will give you field elevation when on the field (normal altimeter setting here in the states)
Fixed it for you. As for the Q part, @Acrofox, I used to know I'm sure when I went to the Harvard of the skies, but it has slipped my mind.

Edit: from Wiki, so it has to be right:
The abbreviation QNH originates from the days when voice modulated radio was often difficult to receive, and communication was done by Morse Code. To avoid the need for long Morse transmissions, many of the most commonly used communications were incorporated into a Q code. To ask for atmospheric pressure at sea-level (i.e., at zero altitude) the letters 'QNH' would be transmitted. A common mnemonic for QNH is "Nautical Height", (whereas the mnemonic often used for QFE is "Field Elevation").
http://en.wikipedia.org/wiki/QNH
 
Fixed it for you. As for the Q part, @Acrofox, I used to know I'm sure when I went to the Harvard of the skies, but it has slipped my mind.

Edit: from Wiki, so it has to be right: http://en.wikipedia.org/wiki/QNH
Actually, I'm a radio geek, so the concept of Q-codes itself isn't what needs explaining. My question is ... for practical purposes, what do you -do- with them? Why do they exist, etc. How do you use them, what difference does it make operationally, etc.
 
Actually, I'm a radio geek, so the concept of Q-codes itself isn't what needs explaining. My question is ... for practical purposes, what do you -do- with them? Why do they exist, etc. How do you use them, what difference does it make operationally, etc.
@Stone Cold Nevermind ... I figured it out from the reply above... didn't read that first.

So QNH operation is kinda like normalizing the ground to 0' for aerobatics ... which would give you the option of using +feet for stepdowns on an approach, vice using absolute MSL elevations... yes?

-Fox
 
@Stone Cold Nevermind ... I figured it out from the reply above... didn't read that first.

So QNH operation is kinda like normalizing the ground to 0' for aerobatics ... which would give you the option of using +feet for stepdowns on an approach, vice using absolute MSL elevations... yes?

-Fox
That would be QFE for 0 at field elevation.
 
QFE - Ok... so you set the altimeter, so that when you touch down, it is reading 0 feet correct? What if the field elevation is say 6000 MSL? I'm pretty sure no altimeter setting that is available would make it read 0 at touchdown.
 
QFE - Ok... so you set the altimeter, so that when you touch down, it is reading 0 feet correct? What if the field elevation is say 6000 MSL? I'm pretty sure no altimeter setting that is available would make it read 0 at touchdown.
I think that is because all of the west uses QNH and QNE so are altimeters stay within that most used range. QFE is used mostly in Russia, China, North Korea and some former Soviet countries.

6000' is what around 23 inches?
 
@Stone Cold Nevermind ... I figured it out from the reply above... didn't read that first.

So QNH operation is kinda like normalizing the ground to 0' for aerobatics ... which would give you the option of using +feet for stepdowns on an approach, vice using absolute MSL elevations... yes?

-Fox
Yes, that would be QFE ops. The interesting thing about Russia is now they use QFE below T/L, but have a T/L that is usually around 5000' MSL. So, on arrivals with step-down fixes, you would usually be using QNE. You also get the pleasure of transitioning to Meters at TL/TA. SO, at 5000(ish) you get to wrap your brain around going from feet to meters. See below for more. It's late here in Dubai, so this will be my last post for the night. I could go on more eventually...
QFE - Ok... so you set the altimeter, so that when you touch down, it is reading 0 feet correct? What if the field elevation is say 6000 MSL? I'm pretty sure no altimeter setting that is available would make it read 0 at touchdown.
And this is the reason most of the world uses QNH. The highest elevation airport I've used in my QFE operations is Moscow, at a staggering 700' MSL (I think that's the highest one, anyways...been a long day). They do not have high elevation airports. Even Europe has "relatively" low airports. I want to say the highest elevation airport (at least for jets) is around 5000-6000'. You would have to deal with the limitations of the altimeter, but don't have to in Europe because they use QNH anyways. It's just funny to me to hear "Western" crews request QNH when coming in to Russian airports. Wrap your head around it and it's not bad at all.
 
Doh! Found my answer in the chart legend. Figures...turns out it doesn't matter to civilian pilots hense the reason I didn't know it.

It makes IFR planning much more simple than part 91 rules. If I have what's forecasted in the parenthesis at ETA through 1 hour, I can file there. If the weather isn't forecasted at least 400&1 above it, I need an alternate. To choose an alternate, I need 400&1 above those parenthesis. And we don't comply with Alternate Minimums either. (There are other rules too - just commenting on the weather planning portion.)
 
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