Jump to content

Archived

This topic is now archived and is closed to further replies.

Remys

QNH VS QFE

Recommended Posts

in the landing phase we can choose between QNH and QFE

 

ok so QNH stands for barometric pressure as reported by a particular station (local altimeter setting)

and QFE Altimeter setting referenced to airport field elevation (where field elevation equals zero feet)

 

but when should i use QNH and when QFE and what does it depends on ?

normally which one is used and is it related to approach charts .... ?

 

thank you




 


Remy Sarkis

BAW1031

UAE1525

 

Boeing777_Banner_Pilot.jpg

Share this post


Link to post
Share on other sites

IIRC QFE is only used in Russia (possilby China?-can't remember) QNH is definatley more widely used. I would always use QNH unless given a specific QFE.

 

On the approach chart you will be given the approach minima for different categories of aircraft. These are in barometric altitude and radio altitude. The barometric ones are directly related to the current QNH. (unless in Russia/China? where it is related to QFE)


voz777_zpsa91dce79.jpg

 

"If you can't solve and equation with calculus, you're not using enough calculus" - A wise friend

Share this post


Link to post
Share on other sites

QNH is the current barometric pressure and, if set in your aircraft, will ensure that the zero altitude on your instruments will coincide with the height of the runway. If the barometric pressure varies and you do not reset your instruments, you will be in danger of being above or below the field elevation. QNH is the setting used in commercial aviation.

 

QFE is field elevation and is the altitude above mean sea level of the runway. This value, therefore, does not vary with barometric pressure. QFE is normally only used by GA aircraft which mostly return to land at their departure airfield or fly VFR so that the height above the runway may be visually estimated.

 

HTH


Cheers, Richard

Intel Core i7-7700K @ 4.2 GHz, 16 GB memory, 1 TB SSD, GTX 1080 Ti, 28" 4K display

Win10-64, P3Dv5, PMDG 748 & 777, Milviz KA350i, ASP3D, vPilot, Navigraph, PFPX, ChasePlane, Orbx 

Share this post


Link to post
Share on other sites

QNH is the current barometric pressure and, if set in your aircraft, will ensure that the zero altitude on your instruments will coincide with the height of the runway.

 

Richard, I think you may be a bit confused? When sitting at any airport with the QNH set, the altimeter read the aircrafts height above MSL. This is wht in places like Zurich, the approach minima are 1590 ft on the baro.

 

If you set the QFE, then the altimeter will read zero when on the ground.


voz777_zpsa91dce79.jpg

 

"If you can't solve and equation with calculus, you're not using enough calculus" - A wise friend

Share this post


Link to post
Share on other sites

QNH is the current barometric pressure and, if set in your aircraft, will ensure that the zero altitude on your instruments will coincide with the height of the runway. If the barometric pressure varies and you do not reset your instruments, you will be in danger of being above or below the field elevation. QNH is the setting used in commercial aviation.

 

QFE is field elevation and is the altitude above mean sea level of the runway. This value, therefore, does not vary with barometric pressure. QFE is normally only used by GA aircraft which mostly return to land at their departure airfield or fly VFR so that the height above the runway may be visually estimated.

 

HTH

 

 

You might be thinking of QNE (1013hPa / 29.92inHg).

 

QNH and QFE both vary with barometric pressure, QNH gives altitude above msl, QFE gives hight above a certain point, such as runway threshold.


Jordan Forrest

Share this post


Link to post
Share on other sites

QNH is the current barometric pressure and, if set in your aircraft, will ensure that the zero altitude on your instruments will coincide with the height of the runway. If the barometric pressure varies and you do not reset your instruments, you will be in danger of being above or below the field elevation. QNH is the setting used in commercial aviation.

 

QFE is field elevation and is the altitude above mean sea level of the runway. This value, therefore, does not vary with barometric pressure. QFE is normally only used by GA aircraft which mostly return to land at their departure airfield or fly VFR so that the height above the runway may be visually estimated.

 

HTH

 

These are both remenants of the "Q-Code"

 

QFE = "Qcode Field Elevation" (The Barometric pressure in mm that reads 0 at the runway elevation)

QNH = "Qcode Nautical Height"  (The Barometric pressure in mm that reads 0 at sea level) 

 

Standard QNH = QNE = The average (standard) barometric pressure at mean sea level in the International Standard Atmosphere. aka 1013.25

 

QNE is kinda backwards compared to the other 2.

QFE is an adjustment of the barometer to read 0 on the runway.

QNH is an adjustment of the barometer to read 0 at sea level, and

QNE is the altitude the barometer reports when the Kollsman window is set to 1013.25 Standard Average (which will change when the barometric pressure changes).

 

I guess technically, the 777 altimeter doesn't really have a Kollsman window, but same idea.

 

Back in the old old days, Morse Code was used for ATC (!) QFE1001 is easier to type than BAROMETRICALTIMETERSETTING1001 or even CODEFE1001. "Q" stood for "code". I'v heard it referenced as "Queens-Code" but back when it was invented, the reigning British monarch was a King, so probably not.

 

I guess Q sounded like Code and without the trailing U would be pretty obvious that one wasn't receiving a proper word in Morse.

 

 

Regardless if you get told to descend to 6000ft, QNH 1022, you just plug 1022 into the Kollsman window and head on down to 6000ft.

 

If you get told to descend to 600 metres on QFE 1031, you stick 2000ft into your MCP, Check the Metric window is near enough to 600m, dial up 1031 into the Kollsman window, and head on down.


qfafin.jpg
Trent Hopkinson, 2015 Crewmember of www.mangrove.com.au WorldFlight sim

          Youtube channel www.youtube.com/user/musicalaviator

Share this post


Link to post
Share on other sites

Cva1077 is spot on, dont forget the TA & TL and the correct use of 1013 (FL)(2992). QFE is normally used on finals for 0 alt on landing ang for circuits


Richard Russell

Flight simming since 1985

Share this post


Link to post
Share on other sites

Yes, apologies to all. This is what happens when rushing for a train. I should have given it more thought. :(


Cheers, Richard

Intel Core i7-7700K @ 4.2 GHz, 16 GB memory, 1 TB SSD, GTX 1080 Ti, 28" 4K display

Win10-64, P3Dv5, PMDG 748 & 777, Milviz KA350i, ASP3D, vPilot, Navigraph, PFPX, ChasePlane, Orbx 

Share this post


Link to post
Share on other sites

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    22%
    $5,610.00 of $25,000.00 Donate Now
×
×
  • Create New...