Ron Garret wrote:
Today I departed out of RIL as a passenger on a Citation V Ultra being
flown under Part 135. Despite the winds and terrain favoring a
departure from runway 26, we departed runway 8. One of the consequences
of this was that we needed a 5500 foot ceiling, which we darn near
didn't get and we almost got stuck there.

When I asked why they departed runway 8 instead of 26 (whose departure
minimums require only a 3500 foot ceiling) I was told that the Honeywell
Primus 1000 FMS could not be programmed to properly fly the Squat 1
departure (http://204.108.4.16/d-tpp/0801/06741SQUAT.PDF). In
particular, the procedure requires that the plane fly to YIRDU
intersection before turning towards SQUAT, but the Primus 1000 always
interpolates its turns (i.e. it would start turning towards SQUAT
slightly before reaching YIRDU), and this cannot be overridden.

This all sounded a little farfetched to me. Leaving aside the fact that
it's only a 15 degree turn, I don't understand how any IFR-certified GPS
(let alone one that they would install on a freakin' jet) could not
properly fly a published GPS departure procedure.

Can anyone here shed any additional light on this situation? Is this
really true, or did I get told a tale?

Thanks,
rg

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.