airbrake "lock"

[spiral hinge]

Still is the case since the playtest (mods feel free to rename this bug report into what it actually is) but basically, reaching airbrake seems to "lock" your throttle to airbrake for 0.5 seconds before adding more throttle, as if there was an invisible half negative throttle axis

[swift quiver]

the controls working as intended, just not as you intend them to, you have "use throttle axis negative region" turned off

here is what that setting does:

most throttles output from -1 to +1, but some only do 0 to +1. what you are experiencing is the digital axis, which is controlled by your throttle buttons, going to below 0.