Narrative:

MVFR conditions prevailed with relatively strong winds. We were assigned the nrvana 1 departure; which is an RNAV (GPS) departure from runway 14R. The departure includes a climb on an initial track of 135 degrees to 700 feet; then direct nrvana. Positive course guidance is not available on this departure until reaching 700 feet. On or about the time we reached that altitude; we entered IMC conditions and we were turned over to seattle radar. As we managed the hand off; we began to notice a divergence from the outbound course. Over the next two minutes; while making heading corrections; the divergence continued. During this time; it became apparent that we had entered strong cross winds. As best as I could tell; the maximum divergence was about 0.6 nautical miles which was displayed on the navigation display as a one quarter scale deflection. Seattle ATC gave an immediate left turn instruction; wherein we immediately corrected an additional 40 degrees of heading. The rest of the flight was normal. My concern is a possible loss of separation. While we remained within the lateral boundaries of the bfi class D airspace; our cleared altitude reached 2200 feet before we were able to diverge back to the center line. This could have resulted in a traffic conflict with aircraft arriving at seatac. I recommend the departure be redesigned to allow for positive course guidance be provided at 600 feet versus 700 feet; which is the standard for an rnp 1 departure. Given the complexity of the airspace in this region; positive courser guidance at a lower altitude would reduce the risk.

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Original NASA ASRS Text

Title: GA flight instructor reported a slight course divergence due to strong cross winds could cause a possible loss of separation. Reporter recommended the departure procedure be redesigned.

Narrative: MVFR conditions prevailed with relatively strong winds. We were assigned the NRVANA 1 Departure; which is an RNAV (GPS) departure from Runway 14R. The departure includes a climb on an initial track of 135 degrees to 700 feet; then direct NRVANA. Positive course guidance is not available on this departure until reaching 700 feet. On or about the time we reached that altitude; we entered IMC conditions and we were turned over to Seattle radar. As we managed the hand off; we began to notice a divergence from the outbound course. Over the next two minutes; while making heading corrections; the divergence continued. During this time; it became apparent that we had entered strong cross winds. As best as I could tell; the maximum divergence was about 0.6 nautical miles which was displayed on the navigation display as a one quarter scale deflection. Seattle ATC gave an immediate left turn instruction; wherein we immediately corrected an additional 40 degrees of heading. The rest of the flight was normal. My concern is a possible loss of separation. While we remained within the lateral boundaries of the BFI Class D airspace; our cleared altitude reached 2200 feet before we were able to diverge back to the center line. This could have resulted in a traffic conflict with aircraft arriving at SEATAC. I recommend the departure be redesigned to allow for positive course guidance be provided at 600 feet versus 700 feet; which is the standard for an RNP 1 Departure. Given the complexity of the airspace in this region; positive courser guidance at a lower altitude would reduce the risk.

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.