An M98 Controller receiving training experienced an over take loss of separation event with two arrival aircraft on final.
Synopsis
An M98 Controller receiving training experienced an over take loss of separation event with two arrival aircraft on final.
Narrative
MSP weather: 32007 KTS 2 1/2nm -DZBR OVC 006; strong northeast winds at altitudes above 7;000. I was on OJT (on the job training) at North Approach (N) doing ILS 30 L/R approaches to MSP. Air Carrier X was cleared for the ILS 30R approach with a speed of 170 KTS to JACKO (FAF) followed by Air Carrier Y descending to 4;000 from 7;000 with a speed restriction of 170 KTS indicating 233 KTS. Air Carrier Y was given a 280 heading to intercept the 30R localizer; instructed to cross SAMMZ at 4;000; cleared ILS Runway 30R approach maintain 170 KTS to JACKO (FAF). Upon getting established on the localizer; Air Carrier Y's speed was still 100 KTS greater than Air Carrier X ahead and was issued a speed reduction to 150 KTS to JACKO. Just prior to shipping the aircraft to MSP; I instructed Air Carrier Y to reduce to final approach speed because the aircraft's speed was still 100 KTS faster than Air Carrier X ahead and contact MSP. Per RADAR replay; separation was lost as Air Carrier Y began crossing JACKO with a 90 KT overtake behind Air Carrier X. The MSP Controller on initial contact reduced Air Carrier Y to final approach speed and informed Air Carrier Y that they were 90 KTS faster than Air Carrier X ahead. The MSP Controller made a different transmission then returned to Air Carrier Y and canceled his approach clearance upon noticing that Air Carrier Y was not slowing. Air Carrier Y did not respond. The MSP Controller had to make three transmissions to Air Carrier Y to cancel their approach clearance and issue missed approach instructions. Recommendation; data blocks that turn; say yellow; similar to TARP when separation may be lost if actions are not taken and then data blocks that turn red when separation is lost.
Second reporter narrative
I was conducting OJT on the north arrival position at M98. The Developmental issued Air Carrier X approach clearance and 170 KTS to FAF; Behind Air Carrier X was Air Carrier Y the aircraft was slowed initially to 210 KTS; when the aircraft was approximately 6 miles in trail the Developmental cleared and slowed the aircraft to 170 KTS to FAF. The aircraft didn't slow as expected and separation was lost as Tower cancelled the aircraft approach clearance. I was providing instruction to the Developmental and did not catch the overtake in a timely manner. After reviewing the tape; it appeared that Air Carrier Y did not slow as quickly as all the other aircraft; and it was not caught quick enough. Recommendation; I believe I need to pay closer attention while performing OJT. And to my Developmental; and to not be afraid to take quick and decisive action when an overtake situation is occurring.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.