Narrative:

It became apparent last year that there was a problem with one of the approaches that gum pilots use frequently while flying thought the micronesian islands - tkk RNAV 04. One of our safety committee volunteers; xxxxxxxxx; has put in a good amount of time and effort to illustrate the challenges that we face when flying this approach. He was the first to make note of the error; and then he set out to understand what was going on. He was able to sort it out and then he created this document that I have attached. We've been talking about this problem for well over a year; and we understand that the cpo {chief pilot office] is advocating for an updated approach. Unfortunately we haven't seen any changes; at least not quickly enough.background - tkk 04 RNAV: dda - 470 feet alt when passing hamax (map) - 660 feetthe problem is that the profile depiction shows that with a 3.0 degree glide path; the aircraft will pass hamax at the MDA of 420 feet. That's a trap that a lot of pilots are falling into. What is happening is that when the plane passes hamax; the pilots are expecting the plane to continue descending to the dda of 470 feet. The airplane levels off; power comes up to maintain altitude; and the plane begins a turn to the left for the missed approach procedure. Pilots then take 3 seconds or longer to determine what's going on; then turn the autopilot/auto-throttles off (if still on); pull the power back and steepen the descent to get back on profile. So in a high risk environment with a 6;000 feet; runway we are becoming destabilized within 1;000 feet. What we want to see are several things; but the two most important items at the top of our list is a corrected or improved approach (RNAV rnp); and training/guidance from the company on flying approaches with this setup. All the lcas are aware of this; and I would say that the majority of the gum pilots are as well. However; we feel that this approach points to some holes in our training and guidance and we would much rather have this corrected than fly a faulty approach without proper guidance from the FM. Also; we vetted this information through our local lcas prior to sending it to you today. It was unanimous; everyone agreed that until the approach is modified or corrected; we need more guidance in the FM regarding the proper way to brief and fly this approach. In addition to the remarks given by xxxxx; the lcas felt that it was most likely the case that tkk 04 is not the only approach in the system that has this error and it would be prudent for the company to review approaches around the system and to alert the crews.we know what the easy answer is; you go missed when you cross the map and the field is not in sight. But the way you brief the approach is that you execute a missed approach when reaching the dda and the field is not sight. Also; even with the field in sight; your flight guidance; and automation if connected; will quickly lead you to a destabilized approach. We would much rather get a clarified procedure from the company and follow published guidelines and procedures than continue to use local knowledge to get by.

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Original NASA ASRS Text

Title: B737 First Officer reported the RNAV approach at this airport causes an unstable approach and more training or a procedure rewrite is needed.

Narrative: It became apparent last year that there was a problem with one of the approaches that GUM pilots use frequently while flying thought the Micronesian Islands - TKK RNAV 04. One of our Safety Committee volunteers; XXXXXXXXX; has put in a good amount of time and effort to illustrate the challenges that we face when flying this approach. He was the first to make note of the error; and then he set out to understand what was going on. He was able to sort it out and then he created this document that I have attached. We've been talking about this problem for well over a year; and we understand that the CPO {Chief Pilot Office] is advocating for an updated approach. Unfortunately we haven't seen any changes; at least not quickly enough.Background - TKK 04 RNAV: DDA - 470 feet Alt when passing HAMAX (MAP) - 660 feetThe problem is that the profile depiction shows that with a 3.0 degree glide path; the aircraft will pass HAMAX at the MDA of 420 feet. That's a trap that a lot of pilots are falling into. What is happening is that when the plane passes HAMAX; the pilots are expecting the plane to continue descending to the DDA of 470 feet. The airplane levels off; power comes up to maintain altitude; and the plane begins a turn to the left for the missed approach procedure. Pilots then take 3 seconds or longer to determine what's going on; then turn the autopilot/auto-throttles off (if still on); pull the power back and steepen the descent to get back on profile. So in a high risk environment with a 6;000 feet; runway we are becoming destabilized within 1;000 feet. What we want to see are several things; but the two most important items at the top of our list is a corrected or improved approach (RNAV RNP); and training/guidance from the company on flying approaches with this setup. All the LCAs are aware of this; and I would say that the majority of the GUM pilots are as well. However; we feel that this approach points to some holes in our training and guidance and we would much rather have this corrected than fly a faulty approach without proper guidance from the FM. Also; we vetted this information through our local LCAs prior to sending it to you today. It was unanimous; everyone agreed that until the approach is modified or corrected; we need more guidance in the FM regarding the proper way to brief and fly this approach. In addition to the remarks given by XXXXX; the LCAs felt that it was most likely the case that TKK 04 is not the only approach in the system that has this error and it would be prudent for the company to review approaches around the system and to alert the crews.We know what the easy answer is; you go missed when you cross the MAP and the field is not in sight. But the way you brief the approach is that you execute a missed approach when reaching the DDA and the field is not sight. Also; even with the field in sight; your flight guidance; and automation if connected; will quickly lead you to a destabilized approach. We would much rather get a clarified procedure from the Company and follow published guidelines and procedures than continue to use local knowledge to get by.

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.