Incident Summary
On April 12, 2015, at 0821 local time, a loss of required air traffic control separation occurred when United Parcel Service (UPS) flight 357, a Boeing 767-300, overflew N900QS, a Cessna C750 Citation, which was holding in position on runway 8L at Miami International Airport (MIA), Miami, Florida. The conflict was detected when the tower's airport surface detection equipment, model X (ASDE-X), alarmed. The local controller (LC) instructed UPS357 to go around and turn 10 degrees left. At the time, UPS357 was at an altitude of 200 feet and approximately ½ mile from the runway 8L threshold. The aircraft overflew the Citation by 475 feet vertically.
Sequence of Events
UPS357 had departed Managua International Airport in Nicaragua at 0628, destined for MIA. N900QS was departing MIA for Chub Cay International Airport in the Bahamas. MIA was handling departing traffic on runways 8L and 8R with line up and wait (LUAW) operations in effect, and arrivals on runways 9 and 12 with land and hold short operations (LAHSO) in effect.
At 0819:48, the local controller directed N900QS to LUAW on runway 8L from taxiway K1. At 0819:57, the controller cleared UPS357 to land on runway 8L. The pilot of UPS357 inquired about interval traffic but was told it was no factor. At 0820:08, N900QS taxied onto runway 8L. UPS357 was on final approach, about 2.7 nm from the threshold.
At 0821:04, an ASDE-X alert was generated. UPS357 was 0.66 nm from the threshold at 325 feet agl. Six seconds later, the controller directed UPS357 to go around, repeating the directive six times, and advised a left turn of 10 degrees, reporting traffic holding on the runway. By 0821:22, UPS357 crossed the landing threshold at about 310 feet agl. Two seconds later, it was directly over N900QS, with vertical separation of approximately 475 feet based on transponder Mode C altitude. UPS357 was re-sequenced for a normal landing, and N900QS departed uneventfully.
Weather and Conditions
Visual meteorological conditions prevailed. The 0753 METAR for MIA reported winds from 120 degrees true at 7 knots, visibility 10 statute miles, few clouds at 2,300 feet agl, scattered clouds at 3,500 feet agl, broken clouds at 25,000 feet agl, temperature 26°C, dew point 22°C, and altimeter 30.09 inHg.
Controller Actions
Tower staffing included a local controller (LC) working combined Local Control North and South positions, a controller-in-charge, a ground controller/flight data, and a cab coordinator. The LC on position was a front line manager (FLM) gaining proficiency time. The FLM had been supervising the tower crew before signing on and had been on position for about one hour, considering traffic routine. He had been using runways 8L and 8R for departures and runways 9 and 12 for arrivals.
An Air Canada A320 had departed runway 8R. Due to the Air Canada aircraft's tendency to slow after takeoff, the LC directed N900QS to LUAW to ensure adequate separation. He then cleared UPS357 to land without advising that traffic was holding on runway 8L, as required by FAA directives. The LC stated that cargo aircraft like UPS357 preferred runway 8L for shorter taxi times.
The LC missed the same-runway conflict until the ASDE-X alarmed, attributing the oversight to distractions from an inbound taxi misunderstanding and a foreign object debris report on a taxiway. After the alert, he issued the go-around and turn instructions.
Aftermath
After being relieved, the LC filed a mandatory occurrence report (MOR) in the Comprehensive Electronic Data Analysis and Reporting (CEDAR) system. The MIA operations manager initially directed the LC to classify the event as non-significant, but it was later changed to "significant" after guidance from the FAA Eastern Service Area. The MOR system defaulted to "non-significant" unless "significant" was explicitly selected at that time.