QFE help

[Sparc]

I'm taking off from creech base in Nevada. ATC tells me QFE 26.75 so I try adjusting the value but it stops at 28.10. My altitude on hud says 1,420 ft. Did watch grim reapers videos as well as others and I understand (sort of) how Q codes work. I'm embarrassed for sure but I have to ask for help as to why the barometric setting knob limits me from 26.75 QFE. Help

[Frederf]

Don't fly QFE with the F-16, it wasn't designed for it, nor is pretty much any other modern NATO jet. Some Russian jets have super low altimeter knobs so they can do QFE over a wider range of elevations/temps but even they run out some times and have to do alternate ops.

[Raptor9]

Yeah, using QFE on aircraft equipped with radar altimeters (or any other device that gives you AGL altitudes) is especially silly.

[Sparc]

Understood.  The viper doesnt have a radar altimeter is this true? 

 

During poor visibility (havent tried yet) do you still land the viper without messing with the QFE settings? 

[Tholozor]

20 minutes ago, Sparc said:

Understood.  The viper doesnt have a radar altimeter is this true? 

The F-16 has a radar altimeter. The power switch for it is on the sensor power panel next to the FCR power switch.

[Sparc]

Still learning here xD thank youu

[TobiasA]

vor 4 Stunden schrieb Sparc:

Understood.  The viper doesnt have a radar altimeter is this true? 

 

During poor visibility (havent tried yet) do you still land the viper without messing with the QFE settings? 

You do this with ILS if conditions are really poor.
If you don't have ILS, a radar fix, markpoint on it and a radial will work- not quite the same, but better than guessing where you are. Pay attention to the radar altimeter in that case, it is displayed in the HUD followed by an "R" to indicate it is the radar altitude that is displayed there.

[Furiz]

Btw if your HUD scales switch is set to OFF you wont see Radar Altitude as far as I'm aware. It needs to be in VAH or VV/VAH to show radar alt. You can see radar alt just above Altitude Low setting and radar alt is marked with R.  And as far as I'm aware HUD Altitude switch has no effect on altitude displayed on the HUD.

In our sim, not sure how it is supposed to be in real life.

Edited February 5, 2022 by Furiz

[Raptor9]

19 hours ago, Sparc said:

During poor visibility (havent tried yet) do you still land the viper without messing with the QFE settings? 

Yes, you just reference the field elevation of the airfield you are landing at. If not using a kneeboard approach plate, you can click on the airfield icon in the F10 map to see the elevation. You just keep this in mind.

ILS approaches will have a Decision Altitude (DA) associated with it, that when you arrive at this altitude during the descent, if you haven't broken out of the clouds and see the runway, you should execute a missed approach. This is typically 200 feet above the runway elevation. So if the airfield elevation in the F10 map was 500 feet (we'll assume the runway is the same elevation as the airfield elevation since they are normally very close if not the same) then the DA would be 700 feet.

You can use this information one of two ways. If you press ICP button "2/ALOW", it will bring up the altitude warning page on the DED. You will see CARA and MSL FLOOR. The CARA altitude will give you a warning based on AGL altitude and the MSL FLOOR will give you a warning based on MSL. I typically just set the CARA at 200 feet so it goes off at DA (more or less), but you could set the MSL FLOOR value based off the field elevation value from the F10 map (or the actual approach plate on the kneeboard) so that it provides the same warning more reliably.

This way you don't need to bother with QFE, but still have accurate warning when approaching elevation of the field you are attempting to land to. Just keep in mind that is based on the assumption that you have an accurate barometric pressure altitude setting, since if that is wrong, your barometric altitude is off, and therefore so will the MSL FLOOR altitude warning. The altimeter setting (QNH) should automatically populate in the brief screen before the mission. You could also adjust this on the ground before takeoff until the baro altimeter matches the altitude of the airfield.

Edited February 6, 2022 by Raptor9

[Sparc]

Fantastic help this really helps thanks

[Bunny Clark]

Western ATC shouldn't even be giving you pressure in QFE at all, it should be QNH pressure at sea level. I hope that'll be fixed with the ATC overhaul. 

[Jester2138]

Pretty sure QFE is mostly just a UK thing. I've never heard it used in the U.S. at all (except for aerobatic competitions). DCS ATC certainly should use QNH as is the ICAO standard, but... DCS ATC... is what it is.

Edited February 6, 2022 by Jester2138

[AlexCaboose]

Adjust your altimeter to QNH.

[Machalot]

On 2/5/2022 at 4:54 PM, Jester2138 said:

Pretty sure QFE is mostly just a UK thing.

Don't forget the Viggen! QFE is central to most weapon employment. That's target QFE, of course, but the landing navigation mode also uses field QFE to create the HUD symbology, and I think to place the flight directors on the ADI.

Edited February 7, 2022 by Machalot

[DmitriKozlowsky]

Perhaps I am incorrect. Or how this should be handled in RL. But I disregard DCS: ATC QFE or QNH calls. In DCS any start in air, will have altimeter set automatically correct. Mostly I start cold from ramp. I set the altimeter, after start up, to Electric source, and set QFE/QNH rotary so that altimeter reads same elevation as my parked aircraft , which I get from F2 or F10 view. Note that this is for air data sensor fed altimeter. NOT the radar altimeter, which is a different instrument. But there is also a procedure that states that altimeter should be adjusted such that it reads ZERO on parked aircraft. So that if you landing at same field that was departure field, and there is no radar altimeter, you know exactly how high you are above ground. My inner voice tells me to set my altimeter so that it reads same elevation as my parked aircraft. This makes more sense to me.

QNH and QFE difference is both simple and confusing at same time. QFE is Query Field Elevation above mean sea level corrected for ambient temperature. In DCS, and in RL, 20C(68F) at sea level the altimeter setting is 29.92. 

In DCS, and about same in RL, air data altimeters are accurate to 33 feet. I was skeptical at first. But apparently air pressure at 33 feet above sea level has measurable difference then at ground level.

[Bunny Clark]

15 minutes ago, DmitriKozlowsky said:

I set QFE/QNH rotary so that altimeter reads same elevation as my parked aircraft , which I get from F2 or F10 view.

You can also just read the current barometer settings from the briefing under the WEATHER heading. 

[DmitriKozlowsky]

On 2/4/2022 at 6:25 PM, Frederf said:

Don't fly QFE with the F-16, it wasn't designed for it, nor is pretty much any other modern NATO jet. Some Russian jets have super low altimeter knobs so they can do QFE over a wider range of elevations/temps but even they run out some times and have to do alternate ops.

So the obvious question. Why is DCS ATC giving us useless QFE?

[Tholozor]

The ATC script is very old, probably dating back to the original Ka-50 days or even Flanker 2. Eastern aircraft generally are able to use QFE, so the ATC was originally designed with that in mind.