Unstable Turn and Establishing on Track

[freeze1058]

Hi,

upon turning final for KL35 RNAV (GPS) 26 the aircraft had difficulties keeping the track. Upon initial turn it overshot left, then corrected hard and overshot right, again left, etc.

2020-5-24_22-15-21-230.jpg (220.42 KiB) Viewed 729 times

Wind/turbulence was no issue. Turns felt exagerated up to 45 degrees bank, which resulted in numbers overshots of the track, until the aircraft stabilized.

Sorry to say, but after feeling confident to have a stable product I feel kinda disappointed considering the number of issues during this short flight (see separate posts, all from KSBA-KL35).

Cheers,

Stefan

[henrik.bergvin]

Hi,

upon turning final for KL35 RNAV (GPS) 26 the aircraft had difficulties keeping the track. Upon initial turn it overshot left, then corrected hard and overshot right, again left, etc.

..snip..

Stefan

I spoke to a pilot who used to fly the 350i before upgrading to jets, and he confirmed that the autopilot was kind of poor at catching the final approach (ILS or RNAV or otherwise) if the turn was too great. He suggested to me to make as shallow a capture angle as possible.

However, I agree with you that it feels like it overcorrects, and the high bank turns really make it feel unstable. I don't think I've ever managed a smooth capture of the ILS, even if I do as shallow as maybe 25 degree intercepts.

[Taguilo]

Hi,

upon turning final for KL35 RNAV (GPS) 26 the aircraft had difficulties keeping the track. Upon initial turn it overshot left, then corrected hard and overshot right, again left, etc.

Wind/turbulence was no issue. Turns felt exagerated up to 45 degrees bank, which resulted in numbers overshots of the track, until the aircraft stabilized.

Hi,

First, max bank with autopilot On (and depending on other factors) is 30 degrees, as it is shown in your image. It might feel as 45, but it is not.

Now, there will be overshoots always with leg turn angles greater than 70 degrees, more or less severe, like in the real aircraft. And severity will be more noticeable both at low speeds, as is your case (130 kias) and high ones (above 200-220 kias)

Sorry to say, but after feeling confident to have a stable product I feel kinda disappointed considering the number of issues during this short flight (see separate posts, all from KSBA-KL35).

I've made a comment in that post. And in the image you show here, that comments also applies.
Notice that both FPTA (Flight Plan Target Altitude) in PFD and VNAV altitude constraint in MFD display in amber, which means constraint was violated - min altitude to cross it is 9400 or above and you are leveled below that, at 8700.

I'm pretty sure you didn't know the meaning of those limitations, hope you can understand it better now.
This is a complex aircraft indeed and many factors must be taking into account to succeed in flying a smooth approach.


Tomas

[freeze1058]

I've made a comment in that post. And in the image you show here, that comments also applies.
Notice that both FPTA (Flight Plan Target Altitude) in PFD and VNAV altitude constraint in MFD display in amber, which means constraint was violated - min altitude to cross it is 9400 or above and you are leveled below that, at 8700.

I'm pretty sure you didn't know the meaning of those limitations, hope you can understand it better now.
This is a complex aircraft indeed and many factors must be taking into account to succeed in flying a smooth approach.


Tomas

Hi Tomas,

true, the vertical path on this approach was messed up, thus I didn't take it into consideration. The whole RNAV thing remains a challenge to understand, thus I might get back to it in the other post.

Thanks for your support!

Cheers,

Stefan