The Federal Aviation Administration (FAA) has confirmed that Delta Air Lines and United Airlines planes were involved in a near-miss in Phoenix, Arizona, on January 11.
Loss of required separation
The Federal Aviation Administration (FAA) issued a brief statement stating that Delta Air Lines and United Airlines aircraft both landed safely after losing needed separation while inbound to Phoenix Sky Harbor International Airport (PHX) on January 11.
“Both flight crews received onboard alerts that the other aircraft was nearby. Air traffic control issued corrective instructions to both flight crews.”
According to the regulator, the aircraft involved were a Delta Air Lines Airbus A330-300 (N820NW) and a United Airlines Boeing 737-900ER (N68891).
The former was flying DL1070 from Detroit Metropolitan Wayne County Airport (DTW), while the latter was flying the scheduled route UA1724 from San Francisco International Airport (SFO).
The FAA said that the incident occurred about 11 a.m. local time (UTC-7). According to Flightradar24, both flights were on collision course above Estrella Village, a community near Phoenix, Arizona.
Entering holding patterns
According to Flightradar24 data, the aircraft were still on their typical flight paths at 11:58:19, as they lined up for an approach on one of Phoenix-Sky Harbor’s runways. However, at 11:58:58, the aircraft lost the required separation and aborted their approaches.
Delta Air Lines and United Airlines flights entered holding patterns above Phoenix, with the A330-300 going north and the 737-900ER flying south.
The Delta Air Lines A330-300 safely landed on runway 08/26 at 12:08, and the United Airlines 737-900ER landed on runway 07R/25L at 11:06 without incident.
Both aircraft flew additional flights on January 11, with the Delta Air Lines twin-aisle jet returning to Detroit before crossing the Atlantic Ocean to Amsterdam Schiphol Airport (AMS).
Despite landing at 16:31 local time (UTC -6), United Airlines’ Boeing single-aisle aircraft UA1400 to Chicago O’Hare International Airport (ORD) was the day’s final flight.
Collision avoidance
Modern airplanes come equipped with either an Airborne Collision Avoidance System (ACAS) Xa/Xo or a traffic alert and collision avoidance system (TCAS).
The FAA characterized the latter system, known as TCAS II, simply as a “airborne traffic alert and collision avoidance system that interrogates air traffic control (ATC) transponders in nearby aircraft and uses computer processing to identify and display potential and predicted collision threats.”
“The system will provide appropriate aural and visual advisories to the flight crew to take action to ensure adequate separation when the computer analysis of the intruding aircraft transponder replies predict a penetration of the protected airspace.”
Meanwhile, ACAS Xa/Xo, which delivers traffic advisories (TAs) and resolution advisories (RAs), is replacing TCAS I and TCAS II with Hybrid Surveillance on aircraft constructed after March 30, 2022. According to the FAA’s technical standard order (TCO), the decision was made to strengthen safety margins, improve surveillance logic, and optimize collision avoidance logic.
The FAA said that it now allows four ACAS II variations in US airspace: TCAS II version 6.04a, TCAS II version 7.1, and ACAS Xa, which contains optional ACAS Xo features.
FAQ
What happened at Phoenix Sky Harbor Airport involving Delta and United Airlines flights?
A near collision occurred at Phoenix Sky Harbor Airport when a Delta and a United Airlines flight came into close proximity on the runway during taxiing. The incident was swiftly managed by air traffic control to prevent any collision.
Were there any injuries reported due to the incident?
No injuries were reported as the aircraft did not make contact, and the situation was brought under control without any physical impact.
What actions did air traffic control take to prevent the collision?
Air traffic control issued immediate instructions to both flights, which helped avoid a potential collision. The pilots of both aircraft promptly complied with the instructions.
Is an investigation being conducted into the incident?
Yes, the Federal Aviation Administration (FAA) is conducting an investigation to determine the cause of the near collision and ensure safety measures are in place to prevent future occurrences.
Did the incident cause flight delays at Phoenix Sky Harbor Airport?
Some flight delays occurred due to the incident as the affected flights had to return to their gates, but normal operations resumed shortly after.
