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Bank angle protection

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Bank angle protection

Old 17th Nov 2014, 05:22
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Bank angle protection

Would this statement for glass cockpit Boeing's be accurate.

The FMC provides Bank Angle Protection when in LNAV in which bank angle will be reduced automatically to provide appropriate protection from low speed buffet.

In HDG Select, the pilot is responsible to provide for reduced bank angle if required using the Bank Limit selector.
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Old 17th Nov 2014, 05:39
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Bank angle protection

Generally the AFDS bank limit will vary depending on speed / flap in both LNAV and HDG SEL. The bank limit selector only affects HDG SEL and will only provide the same protections as those offered in LNAV in the Auto position.
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Old 17th Nov 2014, 09:29
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The OPs statement is as far as i can see correct for the 737, which has no automatic position on its bank angle selector.
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Old 17th Nov 2014, 10:34
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Agreed with Denti.
Heading Select poses a threat when operating at or near maximum levels for configuration, step climbs should always take this reduced capability thus into account.
In LNAV the aircraft protects itself, in HDG SEL the pilot is responsible for this protection.

This is the reason why some operators reduce the bank angle above a certain altitude in CRZ, to anticipate and prepare for an ATC instructed turn during CRZ.
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Old 17th Nov 2014, 14:55
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Alitalia MD-11 Hard Landing at Kai Tak (cockpit view + tower view ) - YouTube
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Old 17th Nov 2014, 18:11
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For the 744, directly from the FCOM:

Rotate - sets AFDS commanded bank limit when in heading select (HDG SEL)
roll mode as follows:
AUTO - varies between 15 - 25 degrees, depending on TAS, flap
position, and V2
5, 10, 15, 20, or 25 - selected value is maximum, regardless of airspeed
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Old 17th Nov 2014, 19:56
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Alitalia MD-11 Hard Landing at Kai Tak (cockpit view + tower view ) - YouTube



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Old 18th Nov 2014, 02:00
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I love that language. Even panic sounds great in it.
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Old 18th Nov 2014, 06:10
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Your statement is half correct.
L-NAV provides Trust Based Roll Protection, i.e. Limits the roll in order not to deviate from speed and altitude.
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Old 18th Nov 2014, 06:35
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Never landed at Honkers but it looks to me like that MD11 is not landing on 13, where there is a clear straight-ahead run out over the water after takeoff, judging by other Youtubes... Also, the parallel taxiway is on the right of the in-cockpit video, whereas the tower video has it on the left...

BOT, "Bank Angle" on the ground is an impressive feat...

Trust Based ... Protection
I knew I could trust it...
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Old 23rd Nov 2014, 11:09
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Bank angle parameters vary if on arr or dep, altitude limits,and max bank angle. The is a difference between bank angle and max bank angle, and that is per ac. There are bank limits to 8degrees below 400 ft as an example
Depending on the ac, the differences allow for course correction in the turn. As with the 737, bank angle is limited to 25degrees, leaving 5 degrees to max bank angle for course correction in the turn.
The 747 will still limit to 18 degrees, leaving the 25 select for course correction.
Course correction may be planned or unplanned, in the case of buffet protection, that is unplanned. ATC correction is currently considered planned
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