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DC-10 Autopilot Questions  
User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Posted (7 years 4 months 1 week 4 days 4 hours ago) and read 5400 times:

Hi,

Just a few questions regarding DC-10 autopilot with INS navigation variant:

1-When MCP has 3 push buttons : INS-VOR/LOC-ILS, pushing INS arms navigation mode by INS, what happens with the current active mode? I mean, suppose Heading hold is active, does the a/c continue flying with HeadHold, until course is captured, then NAV becomes active and HeadHold disables automatically (switch is pulled to off automatically)??
2-What happens if VOR/LOC is active, keeps active until course is captured and NAV becomes active, then button automatically switch to off?? or button remains in the ON position but VOR mode is ignored?
3-When INS button is switched off, to which lateral mode returns the autopilot? ?

Thank you
Tom

7 replies: All unread, jump to last
 
User currently offline113312 From United States of America, joined Apr 2005, 572 posts, RR: 1
Reply 1, posted (7 years 4 months 1 week 2 days 13 hours ago) and read 5263 times:

Those buttons are momentary contact. They do not hold in position so they don't pop out. You observe the mode selections and active modes, for the flight director and autopilot, on the Flight Mode Annunciator panel.

You pretty much have gotten the concept of what happens. The FMA has four windows. Thrust, "Armed", Roll, and Pitch. If you are in Heading Select mode, HDG SEL will show in green on the FMA in the Roll window. If the INS button is pressed, INS will show in amber in the Armed window. When the INS tracking becomes active, the Armed window goes blank and the Roll window will show INS in green. If the ILS button is pressed, ILS is show in amber in the armed window but whatever pitch and roll modes were active (green) such as INS and ALT HOLD remain as such until LOC CAP and GS CAP.

Possible modes include: Thrust= N1, SPD, CLAMP
Armed= ALT, LOC, VOR, INS, ILS
Roll= HDG SEL, HDG HOLD, LOC CAP, LOC TRK, VOR CRS, VOR, GA
Pitch= IAS, V/S, MACH, GS CAP, GS TRK, GA

Of course, there are other modes associated with Autoland and other operations such as Back Course Localizer, Control Wheel Steering and others. There is a lot of versatility and some modes are used more often than others.


User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Reply 2, posted (7 years 4 months 1 week 2 days 7 hours ago) and read 5237 times:

Hi,

Thank you very much for the info! It was just what I was looking for.

And another short ones: I see only one switch for Heading Sel/Heading Hold. How does it work to make any of these modes active?.

A final deduction: I understand that to deactivate one mode (ie INS) you have to select another one (ie VOR), for example the only way to remove any roll mode is to disable autopilot or select CWS.?

-On power up autopilot default to Heading Hold/Vertical Speed like any of Boeing type?

Thanks again

Tom


User currently offline113312 From United States of America, joined Apr 2005, 572 posts, RR: 1
Reply 3, posted (7 years 4 months 1 week 1 day 18 hours ago) and read 5182 times:

The Heading knob not only sets a desired heading and moves a cursor on the HSI and RMI, but pulling out on the knob, momentarily, places the Flight Director and/or Autopilot in the HDG SEL mode. Pressing in on the knob changes to the HDG HOLD mode which will hold whatever heading exists at the time the knob is pressed. Of course, if this is done in a turn, the turn will be stopped. Naturally, the heading will overshoot while the wings are leveling and the F/D and/or A/P will attempt to correct back to the heading that existed at the time that selection was made. This knob is commonly used to change out of some other roll mode such as LOC armed or INS.

What mode the autopilot comes on in depends upon what mode of operation already exists. The vertical speed wheel usually is synchronized with what the plane is doing. So if you are already in level flight, the autopilot will come on in ALT HOLD. If climbing or descending, it would normally come on in V/S. However, it also could come on in GA if the TO/GA button has been pressed inflight or TO if it had been pressed on the ground. In TO or GA, wings level would be commanded and a pitch to approximate V2.


User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Reply 4, posted (7 years 4 months 1 week 4 hours ago) and read 5090 times:

Hi,

Thank you for the info!

Rgds,
Tom


User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Reply 5, posted (7 years 4 months 1 week 4 hours ago) and read 5085 times:

Hi, I forgot this one:

-On the MCP there is a switch to change HSI mode from VOR/RAD to INS. I understand when in the first mode, data sent to HSI (heading, track, etc) is Magnetic, but what happens when changes to mode INS that handles True data (heading, tracking, etc) , does HSI rose adjust to new True data, all the heading bugs, flags, etc adjusting as well??

Thank you
Tom


User currently offline113312 From United States of America, joined Apr 2005, 572 posts, RR: 1
Reply 6, posted (7 years 4 months 5 days 15 hours ago) and read 4960 times:

When in the INS mode, the HSI compass card changes to indicate True and the Course bar shows the True Course output from the active leg on the INS. The CDI (course deviation needle) shows deviation from course left or right. Naturally, if the autopilot is engaged to the INS, the course bar should be centered. On many installations, the bug which normally displays the HDG selected on the heading knob, displays drift angle when in the INS mode.

Of course, the compass cards on the RMI indicators are always showing MAG information.

Why do you ask all of this information? Just interested or trying to teach yourself to fly this thing?


User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Reply 7, posted (7 years 4 months 5 days 8 hours ago) and read 4934 times:

Hi 113312, thanks again for the info, you've been very helpful  Smile

Quoting 113312 (Reply 6):
Why do you ask all of this information? Just interested or trying to teach yourself to fly this thing?

It happens that I've just finished to program a complete INS for flight simulation (CDU,MSU,etc) and need to fit it into a DC-10 navigation system.

Regards,
Tom


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