I have noticed on the last couple of types that I have flown that regardless of altitude or speed, when I open the window, the present airspeed in knots is displayed. Of course, I can press a separate button and it switches over to the present mach number but I remember wondering why the window opened as an indicated speed when I first saw this. I assumed that the designers had their reasoning for the design and that was that.
So I was surprised to learn while reading a couple of incidents on the 737-800 that above a certain altitude, the window will open to the present mach number. And not only that but if climbing with the window open with knots being indicated, there will be an automatic switch over to mach approaching FL 300.
Anybody know the reason for the difference and which design might be better?
https://view.officeapps.live.com/op/...041_final.docx
https://www.atsb.gov.au/publications...r/ao-2014-179/