We can say that practically there are minor differences in AOA for each flight (in the same range of weight). But is there any document that states what flight angle is recommended for each of the flight phases? (takeoff, climb, cruise, descent, and approach)
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2$\begingroup$ Boeing began offering (as an option) an independent AOA indicator on its B737-600 and later models. The article in the link below from a Boeing publication explains the limitations of the AOA indicator's usefulness during normal operations versus using Indicated Airspeed/Mach as appropriate references for takeoff/climb/cruise/approach. Probably does not answer your specific question, but it should provide some insight into the use of an AOA vs indicated/Mach for aircraft performance. boeing.com/commercial/aeromagazine/aero_12/aoa.pdf $\endgroup$– user22445Aug 28, 2022 at 22:24
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1$\begingroup$ I don’t believe these differences are “minor.” A transport-size plane has to operate over a range of weights, and a moving location of CG, that is well beyond anything that can be expressed in a typical POH “table.” 150 KIAS at 90,000 lbs will result in a very different AOA than 150 KIAS at 145,000 lbs. The dispatcher or the crew will calculate specific Vref’s for various stages of flight, and would be using these speeds, and not AOA, to optimize performance during normal operations. The crew may know what the limiting AOA is, but would not know or calculate an “optimum” recommended AOA. $\endgroup$– Max RAug 28, 2022 at 23:21
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$\begingroup$ You are right Max, there can be major changes in the AOA depending on the weight...I will edit the post $\endgroup$– TomAug 29, 2022 at 13:42
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3 Answers
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There's no such thing as "recommended angle of attack".
The angle of attack affects the amount of lift generated by the wing. In level flight, the lift of the wing must exactly equal the weight of the plane, so the pilot is just going to fly at whatever AoA gives that amount of lift.
The amount of lift is also affected by the speed at which the airplane flies. So, if the plane speeds up or slows down, the pilot must adjust the AoA to maintain altitude.
There are also things entirely outside the pilot's control that can change the AoA. For instance, updrafts and downdrafts change the direction of the relative wind, which (momentarily) affects AoA.
answered Aug 29, 2022 at 2:18
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Given that is not possible to give proper generic flight angles (it depends on a lot of parameters), I suggest you to have a look to this site. For example you can have a look to the pilot's notes section. Here you can find different notes i.e you can retreive information of the AoA and aerodynamic configurations used in different phases of the flight (e.g here you can find infos about the landing).
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Normally, in commercial aviation crew operate their aircraft based on speeds and thrust settings. The angle of attack (AOA) that is required for each speed/thrust combination and phase of flight will then be attained by flying the correct speed and thrust setting. As there is no AOA instrument on many (most!) aircraft, this is the normal mode of operation. The speeds which are "recommended" (read: required) for each of these phases of flight are given - or at least roughly explained - in the aircraft manuals, from memory you will have a performance section in the Flight Crew Operating Manual (FCOM) and the Quick Reference Handbook (QRH) for normal and non-normal operations. Some operators elect to publish climb angle data (not: AOA!) for their aircraft in the manuals, and there will be tables for body angle/pitch angle (not: AOA, but at least closer) in the QRH to use as a reference in case the speed indicator fails.
For flying the aircraft, that is all that is required, and the angles are more or less a result of controlling speed and thrust.
If you're really after more detailed data for aerodynamics and flight physics modelling, what you get in the QRH for pitch/power tables may serve as a rough indication for the AOA for various conditions, but it's rounded to whatever crew will be able to read on the instruments and is thus not sufficiently precise for meaningful calculations. More detailed data is only available to aircraft operators and their aircraft performance experts. For example, Boeing used to issue a Performance Engineer's Handbook for their aircraft, which contained more detailed data on aerodynamics and engines. However, these reference books are not publicly available, as from the data you could directly derive information on aircraft performance characteristics which one would rather not share with the competitors.
My favourite book to approximate aero models for real life aircraft, by the way, is Obert's Aerodynamic Design of Transport Aircraft.
answered Aug 30, 2022 at 21:38
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1$\begingroup$ I have bought the recommended book, and it is brilliant: simple, and straightforward with crucial information. Thank you. $\endgroup$– TomAug 31, 2022 at 14:10