Hawker guys FMS question
 

Do the FMSs automatically go into independent mode during approach? If so, does anyone know where there is a reference to this in the manual? Is it linked to the gear up/down position, so that again automatically, the FMSs are again linked when the gear comes up in a go-round?

If linked and a gear fault leads to a ferry flight for maintenance with the gear down, does that mean that the FMS are forced into independent operation?

Was discussing this with another pilot and comparing the 604 with the Hawker in this regard, but lacking the books.

Thanks

Hawker FMS
 

They will not change to independent(initiated transfer) mode unless a deliberate selection to do so is made on the MCDU. As far as I know, there is no way to set it up to do so. There are some pilots who change to independent mode for oceanic flying but very few in my experience. Most everyone keeps the boxes synced all the time, be they Honeywell, Collins or Universal.

I am very intrigued as to why you ask this question?

Curious
 

Because on the Collins Challenger set up, the FMS go independent on approach, and I had a Hawker guy tell me he had a maintenance issue. His FMS went independent when he selected gear down.

I suggested that it was maybe designed into the system on the Hawker? Never having flown one, I didn't know, so asked all you experts out there.

I know the Flight Directors go independent.
Didn't realise the FMS did that too.
Never seen any indication of this.

Good point. I will check up on this and see what the situation is. These things go from off the cuff remark to Prrune, to reading up and checking......

Great stuff.....

Hmmmmm. Think think think.....is it "just" the FD or.....?

Back to the book when I get a chance.

On the Challenger, the FMS remains synched (please explain what you mean independant) however the FD goes independent when APP is selected ie LHS FD driven by LHS ADC, Nav 1,etc... Vice versa with RHS FD.

hawker isn't cat 2 so it doesn't need to do that with the FD's. I don't think its config that triggers the dual coupling and independent FD's on a challenger - its a rad alt or baro alt driven change to comply with the requirements of a cat 2 approach. On the challenger it couples the autopilot to both sides as well (it does on the rusty old one I used to fly). I don't know of any aircraft that switches the FMS mode automatically except in the event of a failure.

Most of the ones that I flew actually were. :eek:

ah well I'm wrong then. I've never flown one. I asked a mate that does fly them and he said they aren't a cat 2 aircraft but he's obviously a tool.

Sorry for misleading the original poster. In that case its likely to be similar logic to the challenger.

(I hate posting misinformation on prune and I humbly apologise to all - I shall lambast myself with a hawker manual immediately)

Proline21
 

I happen to be rated on the 605 as well as on the Hawker, and on both airplanes the Flight directors use independent Nav sources after the auto transfer, but the FMS stay synced.

Yep......
 

Right! They remain in sync........

Thanks

ABOUT FMS going indep.
 

Hi everybody,
Up till know (and that is about 900 hours) flying a Hawker 900XP with Collins ProLine 21, I found the FMS's go (or are) "indep" when begining your job from a "dark cockpit" or, after a FMS or database update procedure.
Once you are "ON", I only remember having changed the mode operated thru the CDU by a crew member.