Narrative:

Aircraft X departed anc on the KNIK2 SID. The system flagged the aircraft for a low altitude notification due to insufficient turn or climb. I issued a low altitude alert with instructions to immediately turn left and climb. The aircraft complied with the instructions and [that] alleviated the altitude alarm. I instructed the aircraft to resume a normal rate of climb and no further issue was noted.the KNIK2 departure does not seem to be properly interpreted by most autopilot systems as they omit the 2000 MSL ability to begin a left turn. This can cause the aircraft to proceed all the way to 4 DME before initiating their bank. For most aircraft; this is no issue. For aircraft with limited maneuverability or low bank angle settings; the lagged turn can cause unnecessary proximity to the terrain. In its current state; the KNIK2 departure almost needs to be hand-flown by heavy aircraft in order to prevent the system from alarming. A NOTAM that would require pilots to fly the departure by hand could prove immediately useful.as a more permanent solution; in lieu of RNAV procedures (currently underway); amending the legacy procedures to include a 'do not penetrate' DME arc and depicting terrain would be beneficial to aircraft unable to adhere to the upcoming RNAV sids. A graphical depiction of a DME arc; as a hard-line boundary; would serve as a visual queue to pilots that an important restriction exists. The current restriction we have is more of a footnote that is easily missed by imperfect scans when previewing the procedures. Nearly every pilot I speak to; during post-incident terrain alarms; advises that they are just then seeing the specific notes concerning when to [begin] the turn; or that their autopilot was late with the turn and they had to take over.a graphical depiction of terrain would further server to clearly indicate the severity of the restrictions. As of right now; our eastbound sids depict no such topographic challenge. An unfamiliar pilot on an IMC day could; potentially; be unaware of how rapidly the terrain rises. This could; possibly; exacerbate proximity alters due to a pilot's lack of prioritizing their turn to a safe heading per the design of the SID. I firmly believe that these small changes will have a positive and lasting impact for the anchorage traffic during extended periods of runway 7 departure flows. An RNAV SID will be great in the future; but these legacy procedures can serve as an archaic instrument for pilots who may be unable to perform them due to insufficient equipment or training.

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Original NASA ASRS Text

Title: A11 TRACON Controller reported aircraft autopilot systems on the KNIK2 SID often fly it incorrectly; resulting in a low altitude alert. Controller suggests a SID redesign.

Narrative: Aircraft X departed ANC on the KNIK2 SID. The system flagged the aircraft for a low altitude notification due to insufficient turn or climb. I issued a Low Altitude Alert with instructions to immediately turn left and climb. The aircraft complied with the instructions and [that] alleviated the altitude alarm. I instructed the aircraft to resume a normal rate of climb and no further issue was noted.The KNIK2 Departure does not seem to be properly interpreted by most autopilot systems as they omit the 2000 MSL ability to begin a left turn. This can cause the aircraft to proceed all the way to 4 DME before initiating their bank. For most aircraft; this is no issue. For aircraft with limited maneuverability or low bank angle settings; the lagged turn can cause unnecessary proximity to the terrain. In its current state; the KNIK2 Departure almost needs to be hand-flown by heavy aircraft in order to prevent the system from alarming. A NOTAM that would require pilots to fly the departure by hand could prove immediately useful.As a more permanent solution; in lieu of RNAV procedures (currently underway); amending the legacy procedures to include a 'do not penetrate' DME arc and depicting terrain would be beneficial to aircraft unable to adhere to the upcoming RNAV SIDs. A graphical depiction of a DME arc; as a hard-line boundary; would serve as a visual queue to pilots that an important restriction exists. The current restriction we have is more of a footnote that is easily missed by imperfect scans when previewing the procedures. Nearly every pilot I speak to; during post-incident terrain alarms; advises that they are just then seeing the specific notes concerning when to [begin] the turn; or that their autopilot was late with the turn and they had to take over.A graphical depiction of terrain would further server to clearly indicate the severity of the restrictions. As of right now; our eastbound SIDs depict no such topographic challenge. An unfamiliar pilot on an IMC day could; potentially; be unaware of how rapidly the terrain rises. This could; possibly; exacerbate proximity alters due to a pilot's lack of prioritizing their turn to a safe heading per the design of the SID. I firmly believe that these small changes will have a positive and lasting impact for the Anchorage traffic during extended periods of Runway 7 departure flows. An RNAV SID will be great in the future; but these legacy procedures can serve as an archaic instrument for pilots who may be unable to perform them due to insufficient equipment or training.

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.