oxygen charging
Thats is not quite true most uk airlines carry out oxygen top ups in situ every couple of days which takes out the need to open and close the valve every time.Also with reference to duplicate inspections on oxygen system where I work it is part of the daily check to check the oxygen system and then the pilots come on and do the same check again so a duplicate inspection is a already being carried out.Although it was a maintenance error that caused this problem the pilot obviously did not check the doors page as he would of seen the oxygen contents reading zero so he failed to carry out his checks correctly too.