HUD: HGS 4000 on a B737-800

[globpilot]

Hi,

With the auto-break set at whatever index on a B737-800, have you ever seen if the Flight Path Acceleration symbol is pointing exactly on the Ground Deceleration
Scale on the HUD? FOr example, with auto-brake set to 1, is your acceleration caret point at Ground Deceleration
Scale = 1 on the HUD or merely showing the total of all forces?

thanks

[Derfred]

The deceleration carat will show actual deceleration. It’s an inertial driven indicator, it’s not connected to the brakes.

So, yes, it’s the sum of all deceleration forces.

At Autobrakes 1, in my experience, with normal reverse thrust, deceleration will actually exceed Autobrakes 2 initially (in fact close to Autobrakes 3). The deceleration will reduce with speed until the Autobrakes kick in, and then it should maintain Autobrakes 1.

In other words, the Autobrakes will do nothing until actual deceleration reaches the programmed deceleration rate of the selected Autobrake setting.

Does that make sense?

[globpilot]

It does make a lot of sense. I share the same opinion. However, I was hoping to get some references. I'm testing a Full Flight SIm and my customer thinks the offset between the caret and the number is not right.
Unless I have a clear reference, making my point is challenging,

thanks

[Derfred]

It does make a lot of sense. I share the same opinion. However, I was hoping to get some references. I'm testing a Full Flight SIm and my customer thinks the offset between the caret and the number is not right.
Unless I have a clear reference, making my point is challenging,

thanks

In the aircraft I’ve noted that the selected autobrake will normally slightly exceed the deleration marking on the HGS. I’ve always put this down to Boeing erring on the side of caution.

I’m sorry I can’t help you with references.

[FYSTI]

The reference is in the HGS 4000 Pilots Guide, figure 4-25 in the link: HERE (https://www.scribd.com/document/84774262/B737-HUD) or alternative rockwell_collins_HGS-4000_pilot_guide.pdf (https://www4.zippyshare.com/v/OQYBhEuG/file.html)
.

Line experience (>3500 sectors) is it is accurate . I would be suspicious of the simulator model. The HUD doesn't work well in the sim as it is focused on infinity, and you are only looking at the displays a metre away.