The problem here is that these keyboards are of crapy design. A normal keyboard on a phone has little metal cups that are vented to retain a normal air pressure, so at different altitudes they function the same. The XV6800 does not have these vents so when you fly the air inside expands quite significantly. and some air will escape or move to another key. When you land the plastic over the keys seals them again so you have some keys that too much air under them (hard press and unresponsive) and some with too little air under them (double types and stuck keys).
Now mattgrantlackey's issues with the XV6800 encompass just about every problem I see on these phones. Basically these are just awful phones, everything about them is terrible, sure they play nice for a week or so, then they fall apart, literally. Don't get another one, just move on to another phone.

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Cactus