Date: 201410
Local time of day: 1201-1800
Location: OKC.Airport, OK
Flight conditions: VMC
Light: Daylight
Aircraft: Falcon 2000
Operator: Fractional
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class C OKC
ATC / advisory: TRACON OKC
Reporter organization: Fractional
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Confusion
Second reporter function: Pilot Flying; Captain
Anomaly: Deviation - Altitude Overshoot; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Chart Or Publication; Human Factors
Primary problem: Human Factors

Narrative: 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.


Second narrative: 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.


Synopsis: DA-2000 flight crew reported confusion interpreting the OKC TRUPR1 RNAV departure and pushed over at 700 AGL triggering a GPWS alert.