Aviation Forum / General / IFR / February 2008

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Ron,

I'm not sure what they were trying to tell you, but there are no "fly
over" waypoints on this procedure, they are all "fly past", i.e. it's
perfectly acceptable (and expected) to anticipate any turns.  Yes, any
competent FMS can handle this easily (though, I'm not familiar with the
Primus 1000 specifically).

Which direction was your destination?  If it was eastbound, this
particular procedure takes you quite a bit out of your way.  Perhaps the
crew wanted to save gas/flight time by departing 8.  That doesn't make
much sense, though, if it meant a real possibility of getting stuck
there, instead of actually departing.  Not only that, but both of the
Rwy 8 DP's allow a 400-1 takeoff minimum, assuming you can maintain 320'
per NM on the climb out, something I would think a Citation could handle.

Happy Flying!
Scott Skylane

You got a tale, on a number of levels, plus I have to wonder about the
competence of that crew.

First, an IFR FME (or for that matter a panel mount) must be able to
handle both flyover (FO) and fly-by (FB) waypoints.  There are two RNAV
DPs for Runway 8 and one for 26.

There is also a VOR/DME based ODP for Runway 8, but not for 26.

So, the basic takeoff minimums apply to the ODP for Runway 8 and to the
SQUAT RNAV DP for Runway 26.  (26: 3400-3 or standard with a min CG of
360/NM to 10,000.  8: 5500-3 or standard with a min CG of 370/NM to 13,000)

The basic Runway 8 takeoff minimums do not apply to the two RNAV DPs for
that runway.  They each have their own takeoff minimums and CGs.  The
two RNAV DPs have the mandatory 400-1 requirement even with a CG,
whereas the "steam gauge" ODP is standard with its climb gradient.

Seems that they were not willing to do any of the three RNAV DPs, thus
opted for the steam gauge ODP.

Not a good choice at this airport.  Runway 26 is downhill and with the
use of the  SQUAT ONE there is virtually no terrain threat.  In fact,
engine failure procedures off Runway 26 should be a piece of cake
compared to Runway 8.

SQUAT is a FB waypoint.  The only FO waypoint for any of the three RNAV
DPs is USUNE.

Squat is speed limited so the turn doesn't occur two early for the AWRAW
or EDUKY transitions.  There is no speed limit for the JNC transition
because there is a very small course change.

And, you say they needed a 5500-1 ceiling for Runway 8.  True, but only
if they couldn't do 370 per mile to 13,000.  If that airplane can't do
that, it shouldn't be doing IMC charters at an airport like Rifle.

Departing on the SQUAT on Runway 26 requires a slightly less climb
gradient and only to 10,000 feet, which is far less demanding.

I can only speculate:

Maybe they don't really know how to do RNAV DPs?  Maybe their database
was out of date?  Maybe they misunderstood the takeoff performance
requirements for each runway?

Bottom line: Anyone with their act together in an RNAV aircraft would
have departed Runway 26.