[Garmin 450 slow "reaction" to high altitude variations]

I clearly remember reading 20m/sec vertical descending in my screen versus 0.8m/sec in same situations near landing, last flight.

How could that be explained?

[Garmin 450 slow "reaction" to high altitude variations]

I think the confusion is that the various available plots are only for the baro data, rather than the GPS data, so if he's looking at those plots, I don't know why it ever seemed to work for him before.

 

I guess it would help if the OP would tell us what screen he's looking at when assessing altitude.

Here it is my last flight landing report from gps from BaseCamp. Look at speed and elevation (5th and 6th column)

 

 

Here's an old report also landing on the same airport

 

 

Same last flight half an hour before

 

 

Here's the plot of the recent flight

 

 

And here's the plot of the old one

[Garmin 450 slow "reaction" to high altitude variations]

To get the true altitude reading open a window

I did that but I had to close it immediately because of women yelling and screaming because of their hairstyle

[Garmin 450 slow "reaction" to high altitude variations]

There isn't a way to shut down the barometric input to the device for the altimeter on a 450. It will always use that method, not GPS measurement, so it only records the cabin pressure in an aircraft.

The two options are for the device to act as an altimeter or barometer (the first assumes you are moving in altitude to explain the difference in pressure, the second assumes you are stationary and that the barometric pressure is changing due to weather).

 

The strange thing is I've travelled that route several times and I always have had real data like 60 feet/sec vertical speed descending instead of no more than 2 ft/sec like last two times.

Big planes fly near 30,000 ft altitude. My 450 reaches that height but much later than real live. Same as when the plane is landed, altitude takes a long while to display real data.

 

That's what Garmin's support answered:

 

The calibrated altitude maintains its accuracy as long as there are no significant changes in air pressure from certain outside forces. Changes in weather are the most significant cause for changes in air pressure, but change in location can also affect the accuracy of the sensor as air pressure can vary from location to location.

 

When experiencing a change in location or weather consider recalibrating the sensor with the known elevation or correct pressure for best accuracy; refer to owner's manual for instructions on calibrating the altimeter.

 

Calibrating the sensor periodically when experiencing changes in air pressure will ensure the highest level of accuracy.

 

The current software version of the Oregon 450 is 6.60. If your device is not up to date, you can update the software with the WebUpdater program:

 

http://www8.garmin.com/support/collection.jsp?product=999-99999-27

 

You might also try a master reset to address the problem:

 

To perform the master reset:

 

Power device off

Press and hold a finger on upper-left corner of display

Power device on while continuing to press corner of display

Release power button once Oregon powers on

Touch 'Yes' on Do you really want to erase all user data? message

 

The device should now be reset to default factory settings, all user data should be removed, and the device should function as expected.

 

Next flight I'll post what happpened after those instructions.

 

Thank you all

[Garmin 450 slow "reaction" to high altitude variations]

I have it for around 4 years.

Traveling by plane I use to check altitude variations: altitude and vertical speed

It was good compairing to airplane displays info.

Now I see slow data variations compairing to real values. If the plane is at 30000ft the gps displays 8000ft and ascending slowly. Same is while descending.

Vertical speed also is wrong. I remember 60ft/sec variations. Now I only see, in the same situation, 2ft/sec.

 

Real slow variations seem to be ok traveling by car in mountains where variations are not radical.

 

What can I do?

 

Thank you