A321neo losing height

[carl01]

Hello,

Around 2 hours into a 5-hour flight, my A321neo (Deluxe 40th Anniversary Edition) started losing height, dropping from a preset 38,000ft to 19,000ft before I gave up.

The autopilot was on and the selected altitude was as mentioned 38,000ft.

This hasn't happened before so any idea what caused it?

Please note I'm not a pilot, just a casual player.

Thanks
Carl

[nsproles]

A321 or C150, aircraft fly and maintain altitude and speed through a combination of power and pitch.  Something was upsetting this and without further information, who knows?  There are so many possibilities but screen shots of your instruments at the time could possibly give a lead as to what was happening.