Barometric Setting?

Do I ever need to input the barometric setting on the Hornet and if I do, how do I do it?

I've skipped through the NATOPS and checked Wags' startup video and Chuck's Guide and although I can find references to Barometric/Altitude setting, there doesn't appear to be anything that tells you where and how to do it.

I've found the adjustment on the standby altimeter, but as you'd expect, changing this doesn't appear to change the main altimeter reading on the HUD.

Maybe I've flown too many airliners, but I would have thought that ATC, at least would require that all aircraft fly at known altitudes, between the 3,000ft, when the Hornet is on radar altimeter, and the standard altitude, 18,000ft on the Nevada map.

Changing the standby setting also changes the hud

Ah, ok thanks.

That seems a little odd, but I'll give it a try. Maybe I had radar altimeter selected when I adjusted it before??

Edit: Yup, that did it thanks. With Baro altimeter set, the altitude reading and baro setting readings both changed as i adjusted the standby altimeter knob, but with Radar altimeter set, just the baro setting reading changed. I suppose that makes some sense, although "standby altimeter" does appear to be a bit of a misnoma if adjusting its setting also amends the primary altimeter.

Look at your HSI Page / DATA / A/C and look at PB15, bottom left

Setting the altimeter in the Kollsmann window changes the system bar alt setting regardless of where that switch is set. The switch only controls what mode you're seeing in the display.

 

The only thing about that altimeter that's standby is the fact that it's there in case the HUD fails. The altimeter is part of the pitot-static system and it provides the information to the HUD display. It is actually the primary altimeter from a system standpoint. The HUD is just a display of various pieces of information from other systems.

 

Oh and the word is misnomer, not misnoma.

Thanks for that, including the spelling lesson :)

Look at your HSI Page / DATA / A/C and look at PB15, bottom left

Thanks.

I'm grounded at the moment, as my Rift has had to go back to the Netherlands, to get a right earpiece issue sorted, but I'll try this when the replacement arrives.

The only thing about that altimeter that's standby is the fact that it's there in case the HUD fails. The altimeter is part of the pitot-static system and it provides the information to the HUD display. It is actually the primary altimeter from a system standpoint. The HUD is just a display of various pieces of information from other systems.

That's absolutely not true. The standby altimeter has nothing to do with HUD displayed altitude beyond the Kollsmann setting.

The standby altimeter is purely mechanical and only takes its static source from one side. The HUD altitude is derived from both pitot static sources and is processed and displayed by the air data computer, which compensates for position error (which the standby altimeter does not).

So, to sum it up, you set the QNH or QNE (depending on the local procedures) only in the standby altimeter and this setting will be used by both the mechanical standby altimeter as well as by the air data computer which processes the displayed HUD altitude.

So, to sum it up, you set the QNH or QNE (depending on the local procedures) only in the standby altimeter and this setting will be used by both the mechanical standby altimeter as well as by the air data computer which processes the displayed HUD altitude.

Yep.

(I think you meant QFE though? QNE is something else, which involves setting a standard pressure of 29.92, generally used when flying at high altitudes)

It's all in the NATOPS.

There are bits of info in a couple of the manuals, but this paragraph covers most of it:

Under normal operating conditions, the air data computer (ADC) compensates for the static source position error. If the ADC fails in flight, the standby altimeter can be used. However, these readings must be corrected by means of the Altimeter Position Error Correction chart

Page 30-5, from A1-F18AC-NFM-210.

edit://

also:

2.12.1.3 Static Pressure. The static sources from each pitot static tube are Td together and this

pressure is supplied to the air data computer. The air data sensor channels 1 and 2, on 161520 AND

UP, also receive static pressure from this Td static source. On 161353 THRU 161519, channel 1 receives

static pressure from the left pitot static tube second source and channel 2 receives static pressure from

the right pitot static tube second source. On all aircraft, the standby flight instruments receive static

pressure from the left pitot static tube second source when the static source lever is set to NORMAL

or from the right pitot static tube second source when set to BACKUP. The static source lever is under

the right part of the instrument panel, forward of the right console. With lever in the horizontal

position, the selector valve is in NORMAL, with lever in the vertical position, the selector valve is in

BACKUP.

There is an audible warning when you break baro and radar settings made in the HSI Page / DATA / A/C.

Does the R ALT setting in the standby give a different warning, shouldn't be a conflict?

Yep.

 

(I think you meant QFE though? QNE is something else, which involves setting a standard pressure of 29.92, generally used when flying at high altitudes)

Yeah, I meant QFE, thanks for correcting me (Even though you also have to use your standby altimeter for setting QNE (29.92) when operating in an airspace that requires you to do so, e.g. in civil airspace above transition altitude :smilewink:)

I also have a question regarding alti setting in Navada. When trying to set the standby indicator to ground level Zero feet I can't. The test range for example. I turn the pressure adjuster all the way down and it still says I'm at 100ft. Some airfields its near 2000ft. How do I set the alti to zero? I must be missing something. I have no problems in the Caucasus map.

Same here in Nevada map.

I also have a question regarding alti setting in Navada. When trying to set the standby indicator to ground level Zero feet I can't. The test range for example. I turn the pressure adjuster all the way down and it still says I'm at 100ft. Some airfields its near 2000ft. How do I set the alti to zero? I must be missing something. I have no problems in the Caucasus map.

You can't, and you're not supposed to be able to, so don't worry you're not doing anything wrong. A setting that results in your altimeter reading 0 at an airfield is QFE. You wouldn't be given this in reality, at least in this situation. The fact that DCS ATC does is a limitation that will be addressed at some point.

Some countries actually use QFE in the terminal area.... just to be different :)

You can't, and you're not supposed to be able to, so don't worry you're not doing anything wrong. A setting that results in your altimeter reading 0 at an airfield is QFE. You wouldn't be given this in reality, at least in this situation. The fact that DCS ATC does is a limitation that will be addressed at some point.

Thanks for that. But I do find it odd. Why wouldn't you want to set alti to QFE/zero? I know i can use radar alt in a jet

. But a question in general. A light aircraft for instance. They fly from Nevada area surely they set alti to zero for takeoff?

"The fact that DCS ATC does is a limitation that will be addressed at some point."

Arrh OK. that clears up my question to you. should have read the whole message!

Thanks again!

QFE in Nevada (likewise in Normandy and Persian Gulf) does not make sense since it is not used in those countries. I assume it goes back to the roots of DCS where there only was the Caucasus theater. A significant portion of the Caucasus map covers Russia and at russian airfields they actually do work with altitudes in reference to the airport/runway threshold elevation. Just look up an approach plate from the Russian AIP.

Just as IvanK wrote, some countries do work with QFE in the terminal area. From a pilots perspective one advantage of QFE over QNH that I could think of is that you are always exposed to the same altitude numbers at the same distances from the runway (assuming a standard 3° path) regardless of the airports elevation. But I am far from being in a position to judge which system is the better. Probably just a question of what you are used to...

Yeah, with DCS's roots being with the Russian KA50, and Russians using QFE, that is the origin for use in DCS.

Practicality is also part of the reason you wouldn't use it in Nevada: if an airfield is a few thousand feet high, it'll take ages to set the altimeter!

QFE is used routinely by GA in the UK, as the vast majority of airfields are at low level. The main benefit is that you fly around the circuit at an easy to read 1,000ft, rather than a more abstract figure.

Yeah, with DCS's roots being with the Russian KA50, and Russians using QFE, that is the origin for use in DCS.

 

Practicality is also part of the reason you wouldn't use it in Nevada: if an airfield is a few thousand feet high, it'll take ages to set the altimeter!

 

QFE is used routinely by GA in the UK, as the vast majority of airfields are at low level. The main benefit is that you fly around the circuit at an easy to read 1,000ft, rather than a more abstract figure.

I don’t believe you are correct. The only countries that I have ever used QFE settings are Russia and Kazakhstan. Everywhere else I’ve ever flown uses QNH (millibars/hectopascals or hundredths of inches of mercury). Instrument procedures will define a Transition Altitude for departures and a Transition Level for arrivals. All that means is that actual QNH is used below the transition altitude/level and standard QNH is used above (29.92 or 1013).

QNH correspond to the airport elevation on your altimeter whereas QFE will show zero on your altimeter.

There seems to be a bug in DCS where the Barometric altimeter setting equals the Radar altimeter. For example, if flying over the water in the Hornet at a constant altitude, if you adjust your altimeter setting, the radar altitude will also change. This is incorrect as the radar altitude will never change as it’s the distance above the water based on the antenna located on the bottom of the airplane.

I don’t believe you are correct. The only countries that I have ever used QFE settings are Russia and Kazakhstan. Everywhere else I’ve ever flown uses QNH (millibars/hectopascals or hundredths of inches of mercury). Instrument procedures will define a Transition Altitude for departures and a Transition Level for arrivals. All that means is that actual QNH is used below the transition altitude/level and standard QNH is used above (29.92 or 1013).

I am correct. I was flying around in an R22 this weekend using it in fact.

For a VFR pilot, is there actually any regulation that prescribes how you achieve flying at 1000ft above aerodrome elevation in the pattern? When taking off you actually have the choice, right? Because even if the tower or some met report provides you with the QNH only, you could still change the pressure setting so thatnyour altimeter reads zero on the runway. Then just fly up until it reads 1000. If you want to use QNH, fine, just add the aerodrome elevation to the 1000 ft and that is your pattern altitude in MSL. It probably is also a matter whether your VFR chart set shows heights AGL or altitudes MSL.

I am correct. I was flying around in an R22 this weekend using it in fact.

Whirleybird... Has go with the FedEx Pilot...:music_whistling:

I am correct. I was flying around in an R22 this weekend using it in fact.

So did the ATIS/AWOS or weather reporting facility at your departure airport actually report the QNE setting or did you put it in yourself? Maybe I'm wrong, but I've never heard of it officially reported or used outside of Russia.