This is what I’ve just sent to the Garmin team:
Dear Garmin team,
the altimeter under 16.70 has a (massive) problem on fast descents.
I did 8 skydives with the release candidate of 16.70.
Barometer set on auto for 2 of them, on altimeter for the other 6.
During the climb to altitude in an unpressurized Cessna Caravan the altimeter worked flawless (used one analog and one digital altimeter for comparison) on all jumps.
However during freefall, there was a massive lack in accuracy. During the skydive the reduction in altitude was way to slow. At opening once the parachute was fully open (always around 720-780m according to the other devices) the watch showed still values between 1800 and 2500 m !!!
Upon landing it slowly came back to 0 on one jump. The other jumps it ended with values between 500m and 1841m.
The watch worked flawless when jumping back in September (sorry - no jumps in between).
My experience in regards to skydiving:
2500+ jumps (both military and civil)
Jumping with digital altimeters 2200+
Jumps with this particular watch 150+
Feel free to contact me via mail or cell-phone.
UPDATE:
Garmin has picked up on this and opened internal tickets.
Fit files of 13 test jumps submitted. Now updated to 17.72 beta to jump with this as well.
UPDATE 2021-07-25:
Still does NOT work with beta 17.75
UPDATE 2021-08-12:
Still does NOT work with beta 18.77
UPDATE 2021-08-23:
Still does NOT work with beta 18.80
UPDATE 2021-08-23:
Still does NOT work with 19.20.
It seems that the processing done by Garmin does cause the problem.
Using the raw data from the barometric sensor (which some activities do) allows you do have accurate values.
UPDATE 2021-10-03
Still does NOT work with beta 19.21
However, it seems that the processing has been altered. The drift away from the real values appears to not be as massive as it has been with previous versions.
UPDATE 2022-05-01:
Still does NOT work with 20.87.
Apparently the processing done by Garmin does still cause the problem. Upon landing, the altimeter still showed the exit altitude of 4100m :-(
Using the raw data from the barometric sensor (which some activities do offer) allows you do have accurate values - during the complete Freefall until landing.
UPDATE 2022-05-28:
Still does NOT work with 21.71.
Upon landing, the altimeter still showed the exit altitude of 4080m :-(
(EPIX 2 with 8.31 worked like a charm)
UPDATE 2022-06-17:
Still does NOT work with 22.10.
Upon landing, the altimeter still showed the exit altitude. 6 jumps all with the same result :-(
(EPIX 2 with 8.37 still workes like a charm)
UPDATE 2022-08-21
Still does NOT work with 23.00.
Upon landing, the altimeter still showed the exit altitude. 18 jumps last week all with the same result :-(
(EPIX 2 with 9.32 starts with “funny” behavior - still have to investigate)
UPDATE 2022-10-14
Still does NOT work with 23.73.
Upon landing, the altimeter still showed the exit altitude or some random altitude that was way above ground. 12 jumps last week all with the same result :-(
(EPIX 2 now overides manual calibration immediately with correct altitude if calibrated to values below 50m. 50m or above values are "accepted" and kept.)
UPDATE 2023-05-19
Still does NOT work with 25.10.
Updating to the latest Beta (25.86) today and will jump again in about 10 days.
UPDATE 2023-05-28
I had two succesful altimeter operations with 13.22 Beta
However also used the tip of described by rinserepeat in one of the latest comments.
Further investigations (jumps) will follow in two weeks.
