AW139 Phase 7
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AW139 Phase 7
I was told by AW that in phase 7 the HDG bug would auto centre on engaging HDG. I have never flown a phase 7 a/c so had no reason to not believe this. I just had a friend of mine who is flying a phase 7 confirm this is not the case. Phase 7 seems to be exactly the same as the previous versions in that if the heading bug is set to something other than the current heading and you engage HDG the a/c will turn to that preselected heading.
Was anyone else told about this auto centering function?
Was anyone else told about this auto centering function?
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Auto centering of the HDG bug should only occur when selecting NAV mode if HDG mode was not already engaged. Only applies to Phase 5 and above, not to Phase 4 which does not auto center.
The rep either mis-spoke or was misunderstood.
The rep either mis-spoke or was misunderstood.
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Might be a slight case of lost in translation.
On the earlier software when you pressed "nav" on the guidance controller (I believe) the system captured "heading" at whatever heading the bug was set to and armed "nav" . which really wasn't very useful.
On the phase 5 if you select "nav" it centres the heading bug first, captures "heading" , arms "nav" and once on track captures "nav" Which works fine.
No idea about phase 7 of course.
On the earlier software when you pressed "nav" on the guidance controller (I believe) the system captured "heading" at whatever heading the bug was set to and armed "nav" . which really wasn't very useful.
On the phase 5 if you select "nav" it centres the heading bug first, captures "heading" , arms "nav" and once on track captures "nav" Which works fine.
No idea about phase 7 of course.
Oh, I can confirm for you that Phase 7 software will not auto-centre the heading bug on selecting HDG mode.
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I agree, I liked the fact that I could pre-select a heading and then just select HDG and it would turn. I was told at the time that this new way was to stop the a/c making un-commanded turns when people were not centring the bug in normal ops.
Anyway, thanks for the confirmation.
Anyway, thanks for the confirmation.
That's a nice feature, especially in the corporate world where procedure is to gently steer with the bug for passenger comfort. I forget the number of times I've witnessed heading mode selected from Nav mode and entered an unprecedented turn. Doesn't impress those on the back benches. 
Last edited by Sir Korsky; 8th Sep 2013 at 20:15.
Just to throw into the mix that on another manufacturer's recent aircraft, the heading bug is not visible by default. If you press HDG it appears, straight ahead. If you preset a heading (eg a radar heading given by ATC) then, on rotation of the heading bug control, it appears and of course then, when you press HDG, the preset heading is used and the heli will turn onto it. No use to 139 drivers, but just a better way of doing it IMO.
Well possibly, but the consequence of that is that the concept of heading not armed (appears straight ahead when engaged) or heading armed (engages on preset heading, obviously) is introduced. It works intuitively without that annoying unanticipated heading change when HDG is selected without having previously considered where the bug was last positioned.
I was not specifically thinking about the EC 225, but several recent types produced by EC. The very existence of this thread implies that AW's MMI has room for improvement in this area.
Maybe 139 pilots like to live in a cloud solely occupied by other 139 pilots, in which case sorry for the intrusion, but on the other hand, some cross-pollination from other types might be helpful in crystallising what to ask AW for next. Or maybe not...
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but the consequence of that is that the concept of heading not armed (appears straight ahead when engaged) or heading armed (engages on preset heading, obviously) is introduced.
That concept is not "introduced" by your version. It is simply another way of doing it and it isn't rocket science.
The same concept is available on the 139 by the color of the bug. Not engaged: cyan color - Engaged: magenta. It's quite clear to all but a blind man.
In any case, there is no "armed" in HDG. It's either engaged (going to and/or holding your heading), or not engaged. "Armed" is a temporary/transition condition which only applies when a mode is selected but not yet captured, such as a nav course or condition which must first be captured prior to being engaged.
