Hello, so I am currently trying to do a flight in the WB Sim Cessna taking off from Homer Airport in Alaska which has an elevation of 84 feet. I have live weather turned on and according to ATIS the altimeter setting is 29.95, however when I set this in the aircraft the altimeter actually shows a negative altitude of a few hundred feet and i am curious if this is normal or not.

So is this normal or am I doing something wrong?

Thanks.

10 minutes ago, jt233 said:

Hello, so I am currently trying to do a flight in the WB Sim Cessna taking off from Homer Airport in Alaska which has an elevation of 84 feet. I have live weather turned on and according to ATIS the altimeter setting is 29.95, however when I set this in the aircraft the altimeter actually shows a negative altitude of a few hundred feet and i am curious if this is normal or not.

So is this normal or am I doing something wrong?

Thanks.

In real life flying , if you saw what you are seeing, you would taxi back to the ramp and have an A and P check your altimeter. 

Also, in the RW when I was flying out of small uncontrolled fields, we simply dialed in the altitude of the airport.  The corresponding BP in the window would have been correct.

In the case of Homer, was there a current metar to compare to?  If there was an accurate metar, the BP should have been correct.  Also, if MS/ASOBO placed the airport at the correct elevation everything should have aligned.  However, if there wasn't a current metar and the weather algorithm (meteoblue) had changed, the BP may have been off.

Several possibilities:

• No current metar
• Improper interpolation by metoblue
• Improper field elevation by creator
• Combinations of the above

Overall, I've found Live Weather to be pretty accurate if the metar is up-to-date.  If it's off, use the old method and dial in the proper field elevation.  As Bob says, it may be time to get the mechanic involved.

1 hour ago, jt233 said:

Hello, so I am currently trying to do a flight in the WB Sim Cessna taking off from Homer Airport in Alaska which has an elevation of 84 feet. I have live weather turned on and according to ATIS the altimeter setting is 29.95, however when I set this in the aircraft the altimeter actually shows a negative altitude of a few hundred feet and i am curious if this is normal or not.

So is this normal or am I doing something wrong?

Thanks.

I just tried this and when I enter an altimeter setting of 29.96 I get a reading close to 60 ft. I got the altimeter setting from the METAR provided by the TDS GTN750. When I clicked on the sim's Live Weather METAR "button" it said no METAR available.

SkyVector shows the elevation of runway 04 at 70.4ft and runway 22 at 74.3ft.

Al

Edited February 2, 20242 yr by ark

1 hour ago, jt233 said:

Hello, so I am currently trying to do a flight in the WB Sim Cessna taking off from Homer Airport in Alaska which has an elevation of 84 feet. I have live weather turned on and according to ATIS the altimeter setting is 29.95, however when I set this in the aircraft the altimeter actually shows a negative altitude of a few hundred feet and i am curious if this is normal or not.

So is this normal or am I doing something wrong?

Thanks.

Hmm, suspiciously close to the standard pressure setting for flight levels  (29.92 for use above the transition altitude), which never gives an actual true altitude/height unless the actual pressure AMSL  is coincidentally  29.92 on that time/day

1 hour ago, jt233 said:

So is this normal or am I doing something wrong?

Try a different airport in another part of the country and see if your altimeter is still off by quite a bit. If so it sounds like an altimeter bug with that aircraft, or maybe some kind of strange Community folder conflict.  Another check would be to try a different aircraft at Homer. 

Al

 

Edited February 2, 20242 yr by ark

28 minutes ago, ark said:

Try a different airport in another part of the country and see if your altimeter is still off by quite a bit. If so it sounds like an altimeter bug with that aircraft, or maybe some kind of strange Community folder conflict.  Another check would be to try a different aircraft at Homer. 

Al

 

Thanks, I actually tried the same airport with a different aircraft and the altimeter showed the correct altitude for the airport in that plane, so it definitely seems like a bug with the altimeter in the WB Sim Cessna.

2 hours ago, jt233 said:

Hello, so I am currently trying to do a flight in the WB Sim Cessna taking off from Homer Airport in Alaska which has an elevation of 84 feet. I have live weather turned on and according to ATIS the altimeter setting is 29.95, however when I set this in the aircraft the altimeter actually shows a negative altitude of a few hundred feet and i am curious if this is normal or not.

So is this normal or am I doing something wrong?

Thanks.

No it’s not normal.  IRL If you have so called “sensitive altimeter” after setting barometric pressure you should be within 75ft of airport elevation . If you are not it either altimeter broken or weather report is incorrect . It is fair to say it should be also apply to the sim

1 hour ago, ark said:

I just tried this and when I enter an altimeter setting of 29.96 I get a reading close to 60 ft. I got the altimeter setting from the METAR provided by the TDS GTN750. When I clicked on the sim's Live Weather METAR "button" it said no METAR available.

SkyVector shows the elevation of runway 04 at 70.4ft and runway 22 at 74.3ft.

Al

If you were at PAHO airport, it does report METARS. Not sure why it was missing in Live Weather. However, the pressure there right now (Friday, Feb 2nd at 23:30Z) is 29.96 in/hg, so it appears Live Weather is injecting the correct value.

Might be some quirk with the new effects of low temps on pressure gradients?

Wasn't able to reproduce when I placed my aircraft there. Reported T was -17C and the altimeter setting gave me the exact runway elevation.

Edited February 3, 20242 yr by jcomm

Something is wrong with either the airport or the air pressure.  If you set QNH on your altimeter it should read the height of the airfield and if you set QFE it should show zero feet.

Not sure why msfs does not give you a QFE actually, though using QNH and subtracting the airfield height is not a major issue for a pilot (assuming that the airfield altitude is correct, of course).

Also bear in mind that some airports have slopes (particularly in Japan 😀) and your altimeter will read differently at each end of the airfield.

Edited February 3, 20242 yr by cianpars

Yep, in my rw flying se use QFE 99%  of the time - soaring in Europe - and when I want an estimate of QNH I simply set the airport reference alto and take the reading from the kollsman window. 

Edited February 3, 20242 yr by jcomm

8 hours ago, jcomm said:

Yep, in my rw flying se use QFE 99%  of the time - soaring in Europe - and when I want an estimate of QNH I simply set the airport reference alto and take the reading from the kollsman window. 

How odd, QFE is really only of use when close to the aerodrome that you set QFE for, general flying around away from the airfield with QFE set is just daft and an invite to bust airspace

Edited February 3, 20242 yr by Lonesome Cowboy Burt

1 hour ago, Lonesome Cowboy Burt said:

How odd, QFE is really only of use when close to the aerodrome that you set QFE for, general flying around away from the airfield with QFE set is just daft and an invite to bust airspace

Airspace doesn't know about gliders 🤣🤣🤣

8 hours ago, Lonesome Cowboy Burt said:

How odd, QFE is really only of use when close to the aerodrome that you set QFE for, general flying around away from the airfield with QFE set is just daft and an invite to bust airspace

It's gets even more wack when you realize gliders use meters instead of feet for altitude (in the regions where I fly)

Some swift mental math is required when sharing airspace with descending gliders and trying to understand their position/altitude reports 😁

Edited February 4, 20242 yr by SAS443