Falcon 2000
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Confusion
Deviation - Altitude Overshoot; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Flight Crew Took Evasive Action
Chart Or Publication; Human Factors
We were cleared for and flew the new (three months old) OKC TRUPR1 RNav Departure off of OKC Runway 17L.  Although both of us have been to OKC many times; this new departure appears to be written so that it has a low altitude level off at 500 ft agl.  (In fact; there are numerous new OKC departures with this same altitude restriction on takeoff.)  As depicted; we thought the TRUPR1 requires a level off on takeoff at 1800 MSL; which is only 500 ft above field elevation.  We briefed in the chocks that it was a low altitude level off required but even then; I never actually realized it was only 500 feet above the field.  On takeoff; I passed through 1800 feet within a few seconds after liftoff.  The PIC; who was pilot monitoring; caught the error and I immediately corrected.  The aircraft went about 200 feet above the 1800 msl restriction at most so it was not technically an altitude deviation from an ATC standpoint.  However; due to the nature of this situation; I feel it is prudent to file this report so that our company; union; and the FAA can take a look at these OKC departures and do something about changing them; either procedurally; or to clarity it.   Since the aircraft was so low; the descent to correct to 1800 msl induced a GPWS warning that we were sinking on takeoff.   This altitude restriction; if it really is a hold down restriction; is a pilot deviation waiting to happen and is unsafe.  After reviewing the departure plate again for this report; however; I really am not sure how the procedure; as published; is expected to be flown because of the 1800 ft language for initial climb and the text on the Routing section; where it says to maintain 5;000 MSL.  I now suspect that it really means to climb to 5000 but to not turn until 1800 ft.  It certainly needs to be written and depicted better; if that is the case.  If that is not the case; and the 1800 ft is a climb and level off altitude; that needs to be change.  500 ft is to low for a jet to be leveling off for anything.  I strongly suggest a clarification be drafted and sent out to pilots; perhaps in the notams; at OKC.Certainly; after looking at this departure plate before departure; we should have seeked clarification from ATC before flying it.  However; my biggest concern is that if this really requires a level off at 1800 MSL; jet aircraft have no business whatsoever flying it and should be refusing to accept it.  It frustrates me that I am not really sure what this departure procedure really is; but then I only have over 40 years of IFR flying experience.
TBIRD 1 RNAV DEP.  POOR charting; page 1 has no altitude except 1800 FT. On 175 heading.  Buried at the bottom of page 2 in the routing is maintain 5000 or as assigned by atc.  Because page 1 is pictorial only there is plenty of room to put the maintain 5000 note.
DA-2000 flight crew reported confusion interpreting the OKC TRUPR1 RNAV departure and pushed over at 700 AGL triggering a GPWS alert.