When passing thought FL300, we are instructed to set the bank angle limiter on the MCP to 10°.

I know one of the reasons for this is that we are thrust limited so maneuver capability decreases.

Are there any other reasons?

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    $\begingroup$ Welcome to the site. Your question is light on detail, what is this in reference to? Please edit and add more information as at the moment there's no way to answer this. $\endgroup$ – GdD Jul 19 '19 at 8:11
  • $\begingroup$ I assume this is about a Boeing aircraft (bank angle limiter on the MCP). Could you add the tag for the specific aircraft you are asking about? Also, I don't think it has anything to do with thrust-vectoring. $\endgroup$ – Bianfable Jul 19 '19 at 8:44
  • $\begingroup$ This specification is request on boeing 737 800 . $\endgroup$ – Gabo Jul 19 '19 at 9:00
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    $\begingroup$ That's technique only, not Boeing procedure. I fly 737's, and we have no comparable procedure, whatsoever. LNAV doesn't limit bank to 10 degrees above 300, so we don't either. I'll personally take off with 30 degrees selected, then after departure vectors are done, I'll set 20 as the limit. If we get small adjustments ("10 left for traffic") I'd use the lowest limit, but that's just me. For the reason behind this required technique, you'd have to ask your boss. Anything we can offer would be guesswork. $\endgroup$ – Ralph J Jul 19 '19 at 11:07
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    $\begingroup$ Oh, and, welcome to Av.SE! $\endgroup$ – Ralph J Jul 19 '19 at 11:08

One reason that comes to mind is as you get closer to the coffin corner, the extra G force due to maneuvering could cause a stall. Quoting from "Stall the Pig",

In the thin air at altitude, jets operate within a very narrow airspeed band between MMO (redline) and the low-speed limit, typically a yellow arc that provides a warning zone prior to a stall, indicated by a lower red line. At high altitudes and high weights, this band—known as “coffin corner”—can be quite narrow, leaving you a mere 10 knots of usable airspeed range, for example. Load up the wing in a turn and that lower redline will quickly move upward toward your airspeed.

By limiting the bank angle, you also limit the G forces, and stay farther away from an accelerated stall.

  • $\begingroup$ Amazing they recommend "powering out of a stall" with tweaked out wings and a small Hstab. Wouldn't power to idle, drop the nose with elevator present a lower risk of correcting AOA without exceeding Vne? They could get these big airliners up there with a B-52 and do a "drop" test to see if tail flips nose down faster than sink increases AOA in a stall recovery. Still plenty of open desert around Edwards these days. $\endgroup$ – Robert DiGiovanni Jul 19 '19 at 14:39

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