"@Francisco Ferreira Thanks for the information, so let's see if they open a PR. By the way, does anybody know whether Serial5 is usable in Copter 3.4 other than for the Nuttx serial console? Pixhawks have to few serial ports :-)
"Maybe I missunderstand your quesition, but you know the PILOT_TKOFF_ALT parameter?
"vehicle climbs automatically to PILOT_TKOFF_ALT alt when taking off in Loiter, AltHold, PosHold, Sport (disabled by default, pilot's throttle input overrides…"