"the aircraft descended continuously at a steady rate over a period of 13½ minutes and the pointers would have been in continuous motion throughout, increasing the likelihood of misreading. the cross hatching in this type of altimeter first appears in a window in the 10,000ft disc at an indicated altitude of 26,666ft and the edge of the cross hatching would have been visible within 2 minutes of the aircraft beginning its descent. at 10,000ft the cross hatching completely fills the window and it remains filled as long as the aircraft is below 10,000ft. thus the cross hatching would have been visible to the crew for a period of about 9½ minutes before the aircraft passed through fl60 and it is a matter of conjecture whether it was still an effective warning to them at that stage of the descent.