Perhaps the intent was to perform the test at the same air density, as many aerodynamic properties, including stalling speed (and also engine performance) depen

Perhaps the intent was to perform the test at the same air density, as many aerodynamic properties, including stalling speed (and also engine performance) depend on density. Also, it is more useful to know how much height was needed to recover, than that there was not enough. The latter can easily be determined from the former.