Comment 29 for bug 1740894

And your fix helps:

Still with SRU version installed:

$ cat /sys/class/dmi/id/modalias
dmi:bvnDellInc.:bvr1.1.9:bd08/08/2018:svnDellInc.:pnXPS159575:pvr:rvnDellInc.:rn0C32VW:rvrA00:cvnDellInc.:ct10:cvr:

So, edit edit /lib/udev/hwdb.d/60-keyboard.hwdb:

evdev:atkbd:dmi:bvn*:bvr*:bd*:svnDell*:pnXPS159575:pvr*
 KEYBOARD_KEY_88=unknown

$ sudo udevadm hwdb --update
$ sudo udevadm trigger

evemu-record shows KEY_UNKNOWN:

################################
# Waiting for events #
################################
E: 0.000001 0004 0004 0028 # EV_MSC / MSC_SCAN 28
E: 0.000001 0001 001c 0000 # EV_KEY / KEY_ENTER 0
E: 0.000001 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- +0ms
E: 3.143316 0004 0004 0136 # EV_MSC / MSC_SCAN 136
E: 3.143316 0001 00f0 0001 # EV_KEY / KEY_UNKNOWN 1
E: 3.143316 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- +3143ms
E: 3.143370 0004 0004 0136 # EV_MSC / MSC_SCAN 136
E: 3.143370 0001 00f0 0000 # EV_KEY / KEY_UNKNOWN 0
E: 3.143370 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- +0ms

>>> RESULT:
The disabling of the airplane mode works now (and enabling still works).