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.

Google
 

Original NASA ASRS Text

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

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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.