Narrative:

The purpose of this as soon as possible is to highlight a safety issue with socal during arrivals into lax. We all laugh; and expect changes in the arrival procedures into lax. This event illustrates the danger that we are faced with. On our arrival; we had planned a 280 KT descent to comply with speed at konzl. During our descent; we were slowed from 280 to 260. During a descent; it is difficult to slow and stay on descent path. Our aircraft was heavy and not slowing very well. After passing konzl; we were given descent via; but sped up to 280 again. Another programming requirement while complying with the various altitudes. Shortly thereafter; we were slowed to 250. After jumping through hoops with the FMC programming; were slowed to 230; then 170. All with a 30 KT tailwind; attempting to maintain altitude restrictions as well as put the aircraft in a position to be stabilized on final approach. During the arrival; the speed changes were so drastic; I went to the old school method of stepping to the next altitude and turned off the automation. I can appreciate automation; but when confronted with the rapid speed change requirements on an LNAV/VNAV arrival; the task at hand becomes quite daunting and even confusing. We were tired; but we both recognized the futility of trying to make automation work; so we reverted to old school procedures. My point here is not to show my superiority; but to point out that the numerous speed changes we are frequently faced with are distracting and possibly dangerous. I don't want to be the crew that is too absorbed in making the automation work that they forget to fly the aircraft. Socal needs to pick a speed and go with it. Multiple speed changes on an arrival lead to non-compliance with chart restrictions and could lead to a dangerous flight condition. The situation doesn't sound that bad here on paper; but it is a concern; and I think that if we don't speak up to ATC; then to them it is tacit approval to continue with this dangerous practice.

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Original NASA ASRS Text

Title: B737 Captain laments the speed changes issued by ATC during the SEAVU 2 RNAV arrival to LAX.

Narrative: The purpose of this ASAP is to highlight a safety issue with SoCal during arrivals into LAX. We all laugh; and expect changes in the arrival procedures into LAX. This event illustrates the danger that we are faced with. On our arrival; we had planned a 280 KT descent to comply with speed at KONZL. During our descent; we were slowed from 280 to 260. During a descent; it is difficult to slow and stay on descent path. Our aircraft was heavy and not slowing very well. After passing KONZL; we were given descent via; but sped up to 280 again. Another programming requirement while complying with the various altitudes. Shortly thereafter; we were slowed to 250. After jumping through hoops with the FMC programming; were slowed to 230; then 170. All with a 30 KT tailwind; attempting to maintain altitude restrictions as well as put the aircraft in a position to be stabilized on final approach. During the arrival; the speed changes were so drastic; I went to the old school method of stepping to the next altitude and turned off the automation. I can appreciate automation; but when confronted with the rapid speed change requirements on an LNAV/VNAV arrival; the task at hand becomes quite daunting and even confusing. We were tired; but we both recognized the futility of trying to make automation work; so we reverted to old school procedures. My point here is not to show my superiority; but to point out that the numerous speed changes we are frequently faced with are distracting and possibly dangerous. I don't want to be the Crew that is too absorbed in making the automation work that they forget to fly the aircraft. SoCal needs to pick a speed and go with it. Multiple speed changes on an arrival lead to non-compliance with chart restrictions and could lead to a dangerous flight condition. The situation doesn't sound that bad here on paper; but it is a concern; and I think that if we don't speak up to ATC; then to them it is tacit approval to continue with this dangerous practice.

Data retrieved from NASA's ASRS site as of July 2013 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.