There have been several posts in this forum which mention that jet aircraft normally fly with a few degrees of Nose Up angle of attack (AOA), in order to maintain level flight.
Recently a member asked about why some airliner's engines are angled downward a few degrees in comparison to the airliner's fuselage centerline (longitudinal axis). It was explained to him that the reason for this was because most jet aircraft fly with a few degrees of "positive deck angle" (nose up pitch), while in level flight, so the downward angled engines are better aligned with the relative airflow while cruising enroute.
My question is ......
Is this photo of a 737-7 a good representation of the nose up pitch angle that jet airliners use (a least the 737), while cruising in level flight? Or is this 737 actually climbing?
I suspect that this 737 is in a slow rate of climb with that angle of attack, however, I also suspect that an airliner's AOA probably increases with higher altitudes in order to maintain level flight because of the thinner air creating less lift. So, I'm not sure if she's climbing or not.
Photo © Patrick Lutz