Collins FMS-3000 - always use APPR mode ?
 

RE: ProLine 21 / Collins FMS-3000

NOTE: Still learning the system, nice and slow, one day at a time, know my limits. With that said :

Getting some different opinions, regarding when/whether to use NAV mode or APPR mode when executing an IFR approach.

The 2005 Rockwell Collins FMS-3000 guide, issued by the manufacturer, says "all approaches should be flown in APPR mode" (p.91), however a few guys at my place advocate

NAV mode: LNAV only Approach, RNAV with MDA, VOR Approach, anything with MDA is NAV mode

APPR mode: anything with a DA

What are the various opinions on this ? I prefer simple versus hard

If the book says always use approach mode, then why the debate?

Modern FMS units are smart enough to know what type of approach you're flying. (You have to program the box with the procedure, right?)

In the two types of aircraft I fly (both with Collins systems), you select a directed mode and the box/autopilot sensitivities change based which mode you've chosen.

In your case, selecting nav instead of approach for a procedure where the FMS is actually using GPS as the primary means of navigation (via an approved overlay), might reduce your safety margins or add slop into the course line. It might also prevent you from being able to properly sequence or use FMS derived VPATH information.

What FlyerJosh said. To expand, if you don't select APPR mode on non-precision approaches, the system will never transition to approach lateral and vertical deviation sensitivity, nor will the course deviation display scaling change appropriately. You should see the "NO APPR" PFD annaunciatior in those situations as well.

good points, thats why I asked

FMS 3000 (525B)

DA - Approach
MDA - Nav

VOR (if green needle) *must be flown in approach mode.

Localizer (no gs) - Nav

Backcourse - BC

where does it say this

and why

PM sent. ;)

Citation CJ3 Airplane Flight Manual / Rockwell Collins Pro Line 21 Avionics Systems Operator Guide for Cessna Citation CJ3

VOR approaches must not be conducted in the NAV mode of the flight director. Use the APPR mode, or manually track the approach course using the HDG mode.this limitation applies to both flight director only and utopilot coupled operation.

Autopilot coupled operation is prohibited during any portionof a VORapproach in which the VOR is located behind the airplane more then 15 miles, unless the HDG mode of the flight directoris being used to manually trackthe approach course.

As to why I would not fly everything in approach mode....What if you are descending to an MDA? Autopilot and or Flight Director will fly right through the altitude. The appropriate mode would be Nav / VS or Nav / VNAV

ok clearly different schools of thought exist on this.....

Don't forget the equipment and/or certifications might be slightly different. We're talking a King Air and Citation here. Even though PL21 may be similar, they may not be authorized to do the same thing...