SCT Controller described a go around event caused by an overtake situation on final reportedly due to tail winds and flawed spacing judgement/s.
Synopsis
SCT Controller described a go around event caused by an overtake situation on final reportedly due to tail winds and flawed spacing judgement/s.
Narrative
IFR; tail wind; we were running staggers. These were the first aircraft I worked. I was warned by the previous controller that there was a tailwind. I slowed both an A320 and a B737 to 220 KTS about 30 to 37 miles from the airport. The A320 was going to follow a heavy so I slowed the A320 to 180 KTS at about 10 miles in trail to the heavy. The A320 seemed to slow normally; as if the tailwind was not that bad; so I was going to let the B737 close up on the A320. I got distracted; and let the B737 get too close; so I slowed the B737 to 160 KTS. I then told the B737 that he was gaining on the A320 ahead and to slow to final. It looked like it was going to work so I switched the B737 to the Tower but then the A320 slowed to about 130 KTS inside the marker. I was using the bat. The Tower called and said they could not provide visual but at that time it still looked like 2.5 to me. I then gave the Tower instructions to break the B737 out for re-sequencing. Recommendation; I should of stopped the B737 approach and had him go around.
Second reporter narrative
While training on the LC1 position; a situation developed between an A320 and a trailing aircraft (B737). Separation on final was collapsing between these two arrival aircraft. The Parallel Monitor had just been opened. The Parallel Monitor contacted the Local Assist (JA) and asked the Controller if 'visual separation' could be applied between these to aircraft. The Local Assist repeated the question; and the Parallel Monitor Controller assumed that the Local Assist had accepted separation responsibility. The Local Assist called the Parallel Monitor back and advised that visual separation could not be utilized. The Parallel Monitor instructed the Local Assist to cancel the approach of the B737; climb them to 3;500 FT; and break them out 'now'. Since the Parallel Monitor airspace continues until the runway threshold; I believed that the Parallel Monitor was responsible for all separation of the B737; including MVA requirements. Had the Parallel Monitor not stated; 'Break them out now;' I would have waited to turn them at a later point. The normal protocol is for the Parallel Monitor to take over the frequency and broadcast control instructions directly to the aircraft. Why this Controller broke the protocol in unknown; but is the major cause in the Operation Deviation/Error. Recommendation; ensure that the Parallel Monitor confirm their responsibility of control to arrival aircraft during simultaneous approaches by being the only one to broadcast control instructions directly to aircraft to prevent or resolve loss of separation; as contained in the Letter of Agreement between LAX Tower and SCT.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.