#2842 altimeter pressure setting is off of METAR in weather dialog

[Benedikt Hallinger]

Hi,
just observed:

• Spawned at EGNX
• Fair weather, Afternoon
• METAR reports "XXXX 012345Z 15003KT 12SM SCT041 FEW200 20/08 Q1015 NOSIG
  PFD "

I expected to set the altimeter to 29.97 (which is also told by the "Metar description" button). this gives an altitude of -160ft.
Turning the wheel to match the airfields altitude (280ft), I get 30.46inHG / 1031hPA.

Something seems of in the weather system or so?

[xDraconian]

A couple of things to consider:

• You are at EGNX, and the METAR is for XXXX... is the metar settings
  being ignored?
• The METAR is for the 1st of the month @ 11:45pm... is it being ignored?
• Dynamic weather doesn't immediately change, but instead it transitions
  toward the reported weather.  I would delay for a bit to see if the
  weather converges toward the reported weather (over perhaps a 5-minute
  timespan.)

These are just guesses at what to further investigate.

Scott

On 11/22/23 1:33 PM, Benedikt Hallinger wrote:

---

[codetickets:#2842]
https://sourceforge.net/p/flightgear/codetickets/2842/ altimeter
pressure setting is off of METAR in weather dialog

Status: New
Milestone: 2020.4
Created: Wed Nov 22, 2023 07:33 PM UTC by Benedikt Hallinger
Last Updated: Wed Nov 22, 2023 07:33 PM UTC
Owner: nobody

Hi,
just observed:
- Spawned at EGNX
- Fair weather, Afternoon
- METAR reports "XXXX 012345Z 15003KT 12SM SCT041 FEW200 20/08 Q1015 NOSIG
PFD "

I expected to set the altimeter to 29.97 (which is also told by the
"Metar description" button). this gives an altitude of -160ft.
Turning the wheel to match the airfields altitude (280ft), I get
30.46inHG / 1031hPA.

Something seems of in the weather system or so?

---

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[Benedikt Hallinger]

<meta http-equiv="content-type" content="text/html; charset=utf-8">

Maybe. But that should not be the Case.

The location and time comes from the preset selection of the weather dialog and thus is expected to be considered.

Also, there is an altitude jump when applying the weather.

Am 23.11.2023 um 07:33 schrieb xDraconian <scttgs0@users.sourceforge.net>:



A couple of things to consider:

• You are at EGNX, and the METAR is for XXXX... is the metar settings
  being ignored?
• The METAR is for the 1st of the month @ 11:45pm... is it being ignored?
• Dynamic weather doesn't immediately change, but instead it transitions
  toward the reported weather.  I would delay for a bit to see if the
  weather converges toward the reported weather (over perhaps a 5-minute
  timespan.)

These are just guesses at what to further investigate.

Scott

On 11/22/23 1:33 PM, Benedikt Hallinger wrote:

---

[codetickets:#2842]
https://sourceforge.net/p/flightgear/codetickets/2842/ altimeter
pressure setting is off of METAR in weather dialog

Status: New
Milestone: 2020.4
Created: Wed Nov 22, 2023 07:33 PM UTC by Benedikt Hallinger
Last Updated: Wed Nov 22, 2023 07:33 PM UTC
Owner: nobody

Hi,
just observed:
- Spawned at EGNX
- Fair weather, Afternoon
- METAR reports "XXXX 012345Z 15003KT 12SM SCT041 FEW200 20/08 Q1015 NOSIG
PFD "

I expected to set the altimeter to 29.97 (which is also told by the
"Metar description" button). this gives an altitude of -160ft.
Turning the wheel to match the airfields altitude (280ft), I get
30.46inHG / 1031hPA.

Something seems of in the weather system or so?

---

Sent from sourceforge.net because you indicated interest in
https://sourceforge.net/p/flightgear/codetickets/2842/

To unsubscribe from further messages, please visit
https://sourceforge.net/auth/subscriptions/

---

[codetickets:#2842] altimeter pressure setting is off of METAR in weather dialog

Status: New
Milestone: 2020.4
Created: Wed Nov 22, 2023 07:33 PM UTC by Benedikt Hallinger
Last Updated: Wed Nov 22, 2023 07:33 PM UTC
Owner: nobody

Hi,
just observed:
- Spawned at EGNX
- Fair weather, Afternoon
- METAR reports "XXXX 012345Z 15003KT 12SM SCT041 FEW200 20/08 Q1015 NOSIG
PFD "

I expected to set the altimeter to 29.97 (which is also told by the "Metar description" button). this gives an altitude of -160ft.
Turning the wheel to match the airfields altitude (280ft), I get 30.46inHG / 1031hPA.

Something seems of in the weather system or so?

---

Sent from sourceforge.net because you indicated interest in https://sourceforge.net/p/flightgear/codetickets/2842/

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[Benedikt Hallinger]

So in the GA Wednesday today I tried to switch to Basic weather. There the same bug occurs.

Tested at Sondrio/LILO

• Airport reports itself at 901ft (274.62 meters)
• METAR was LSZS 101950Z AUTO 19002KT CAVOK M12/M13 Q1022
• Metar parser says: 1022 hPa = 30.18 inHg (which is correct)
• Dialing my Altimeter to 30.18 gives me 1725ft (/position/altitude-ft gives me 1959 ft!)
• Dialing my Altimeter to agree to the reported field elevation gives me 29.29 inHg

[Benedikt Hallinger]

On Samedan/LSZS, about 25 minutes later:

• Airport reports itself at 5599ft
• METAR was LSZS 102020Z AUTO 19001KT CAVOK M11/M12 Q1022
• Metar parser says 1022 hPa = 30.18 inHg
• Dialing my Altimeter to 30.18 gives 5600ft (/position/altitude-ft=5594 ft)

The difference was:

• I applied "Fair weather"
• Then reaplied "Live Data" to or three times...
• Then took the measurements just given.

[Gijs]

Seems like a duplicate of [#2022]. The problem is that, when using advanced/local weather, the actual pressure (/environment/pressure-inhg) does not always match the reported METAR, depending on the advanced settings... I have yet to find what the exact conditions are, but changing the "tile selection mode" to METAR seems to fix it.

[Benedikt Hallinger]

Yes, looks very likely.