Sharing a Runway: Fed Ex vs Southwest at Austin
On Monday, two commercial aircraft had a near-miss on the runway at Austin-Bergstrom International Airport in Texas.
The airport at Austin has two parallel concrete runways which run north-to-south: 18L/36R and 18R/36L. The numbers 18 and 36 signify 180° and 360° and L/R is left or right, as seen when flying towards the active runway.
Earlier that morning, Fed Ex flight FX1432 departed Memphis, Tennessee. The aircraft was a Boeing 767-300, registration N297FE, on a scheduled cargo flight. As the Boeing approached Austin, the visibility was poor with dense fog.
Here are some photographs taken at Austin International that morning.
This is what it looked like this morning at AUS. Lots of go arounds. pic.twitter.com/ywMEZnTovP
— Brandon 🛬 (@onshortfinal) February 5, 2023
I’ve made a transcript of the interactions with Austin Tower. You can listen along with the audio here: https://s.broadcastify.com/audio/KAUS-Twr-2023-02-04-1230z.mp3
Note that runways are always given as individual numbers (one eight left) and the calls are preceded/ended with the station being called and the station calling. I’ve simplified this after the first calls to make the interactions a little easier to read.
FedEx 1432: Austin Tower, Fed Ex 1432 heavy, passing 5.4 for the CAT III ILS one eight left.
This is the Fed Ex flight inbound to Austin. The flight crew refers to themselves as “heavy” to highlight that it is a large aircraft (with a maximum take-off weight of over 136,000 kilos or 300,000 pounds ) and requires more separation from other aircraft to avoid wake turbulence. As an example, in 2017, a business jet was flipped after flying through the wake of an Airbus 380 passing a thousand feet above..
A category III approach is a precision instrument approach that allows flights to continue despite poor visibility. These approaches have a lower minimum decision height than a visual approach. They also specify a minimum runway visual range.
Austin Tower: Fed Ex 1432 heavy, Austin Tower. One eight left RVR: touchdown 1400, midpoint 600, rollout, 1800. 18 left, cleared to land.
The Runway Visual Range (RVR) is a measurement of how much of the runway you can see from the three key positions. The runway has three sensors installed, one at each threshold and one in the centre, in order to give the horizontal visibility for the positions, so that the flight crew know the true visibility for the full landing or take off. For a category III a approach, the runway visual range must be not less than 700 feet at the touchdown point and 500 feet at the midpoint. The decision height, when the aircraft must have the runway in sight, should be no lower than 100 feet.
FedEx 1432: Cleared to land one eight left.
At the same time, Southwest Airlines flight WN-708 was ready to depart from Austin with a destination of Cancun, Mexico. The aircraft was a Boeing 737-700, registration N7827A.
Southwest 708: Tower, Southwest 708. We’re short of one eight left and we’re ready.
Southwest 708 has taxied to the runway and is stopped there (holding short), waiting for permission to enter the runway for their departure.
Tower: Southwest 708, Austin Tower. Runway 18 left RVR: touchdown 1,200, midpoint 600, rollout 1,600. Fly heading 170, runway 18 left, cleared for takeoff. Traffic three miles final is a heavy 767.
Southwest 708: OK, fly heading 170 and cleared for take off 18 left. Copy the traffic.
So now we have Fed Ex cleared to land and Southwest cleared to take-off. Staggered permissions are common and both planes know about each other; however, in the poor visibility, it is also just a little bit tight.
Although this has been trimmed from the recording, there is about ten seconds of silence on the frequency while FedEx continues its approach and Southwest lines up on the runway ready to depart.
FedEx 1432: Tower, confirm Fedex 1432 heavy is cleared to land on 18 left.
Tower: That is affirmative. 18 left, you are cleared to land. Traffic departing prior to your arrival is a 737.
FedEx 1432: Roger.
Moments later, the controller becomes concerned that Southwest is still on the runway.
Tower: Southwest 708, confirm on a roll?
He’s asking if Southwest has started its take-off roll, accelerating on the runway to take off.
Southwest 708: Rolling now.
At this point, Fed Ex is coming in to land and close enough to see Southwest, which is still on the runway. At the point when the Pilot Flying initiated the go-around, they were 150 feet above ground level and 1,000 feet short of the runway threshold (300 metres )
Unidentified voice (since confirmed to have been FedEx 1432): Southwest abort!
Same voice: Fedex is on the go.
The flight crew on the Fed Ex flight has aborted their landing and in the process of a go-around. The phrasing “on the go” is usually used by ATC and in this instance, I think that the flight crew meant to signal to Southwest that the Boeing 767 was overhead.
Tower: Southwest 708, Roger. You can turn right when able.
Tower is responding to Southwest, presumably thinking that Southwest has called that they are aborting. It seems to me that there’s an odd nonchalance here (when able) and it’s not clear whether the instruction is for the aircraft lifting off (in which case he should give a heading) or for the aircraft on the ground (in which case, the aircraft needs to expedite getting off the runway and out of the way of the landing aircraft, there’s no need to give a direction).
Southwest 708: Negative.
I think this is in response to the (Fed Ex) call to abort the take off. Once the aircraft has exceeded the V1 speed on the takeoff roll, it is not safe to reject the takeoff. They must continue. But it’s not clear here whether the Southwest flight crew understand the situation. They are still at risk of a collision: the fast-climbing Southwest aircraft could easy fly into Fed Ex, which is passing above them and still needs to gain airspeed.
FlightRadar24 estimate that the Fed Ex Boeing 767 was 75 feet above mean sea level as it crossed over the Southwest Boeing 737, which was at four feet above ground level. Just to put that in perspective, the Boeing 737 tail is 35 feet high.
The more I look at the above statement, the less I like it. See Jacob’s comment below for a breakdown of the relative heights and altitudes.
Tower: Fedex 1432, climb and maintain 3,000. Then you can turn left, heading 080.
Fedex 1432: left turn 080, 3000.
Tower: Southwest 708, you can turn left heading 170.
Southwest 708: 170.
Here, the controller is separating the traffic, sending Fedex northeast and the Southwest to the south.
Tower: Fedex 1432, turn left heading 360, contact approach on 125.32
Fedex 1432: 25.32, left 360.
The Fed Ex pilot is very calm and professional. I think I’d be shouting at the controller to ensure that he realised what the hell just happened.
At this point, Fed Ex changed frequencies in order to rejoin the pattern and fly another approach.
Tower: Southwest 708, you can contact departures.
And then it was quiet until Fed Ex lined up for the second attempt, which was uneventful. A few minutes later, the following exchange took place.
Fedex 1432: Fedex 1432 is exiting Lima
The Fed Ex flight has landed safely and is exiting the runway at taxiway L.
Tower: Roger. Report clear of the runway. You can join [taxiway] Bravo and contact ground on .9
Fedex 1432: We’ll join Bravo. Ground .9 … and Fedex 1432 heavy is clear of the runway.
Tower: Roger. Sir, you have our apologies. We appreciate your professionalism.
Fedex 1432: Thank you.
Flightradar24 has published a video using the ADS-B data to show the relative positions of the aircraft.
The NTSB is investigating an incident involving a Southwest 737 and FedEx 767 that occurred today in Austin. Initial ADS-B data show the landing 767 overflying the departing 737. We are processing granular data now. https://t.co/twHCydm5ixhttps://t.co/wZ3Z0xKJem pic.twitter.com/nkKVjshXmf
— Flightradar24 (@flightradar24) February 5, 2023
The FAA and the NTSB are investigating. The chair of the NTSB said in an interview that it was “fairly clear that the aircraft came within very close proximity of each other and we believe it’s less than 100 feet.” She compared the incident to the near miss at John F Kennedy last month, when an American Airlines aircraft crossed the runway ahead of a Delta Air Lines flight. The crisis was averted because JFK has Airport Surface Detection Equipment (ASDE-X), which uses radar, multi-lateration sensors and satellite technology to track the position of aircraft and vehicles in and around the airport. Austin does not have this surveillance system.
“Air traffic controllers in Austin could see the FedEx plane coming in, but couldn’t actually see where the Southwest plane was in relation to the FedEx plane because the Southwest plane was on the ground,” Homendy explained. “Had they had that technology … they would have been able to see both the FedEx flight and the Southwest flight.”
That said, it seems odd that Fed Ex Boeing was cleared to land before Southwest had taxied onto the runway. Southwest needed some time to line up and there was no sense of urgency until the Fed Ex flight crew called to confirm that they were right to expect 18L to be clear. Once you take the poor visibility into account, this seems like a very poor decision on behalf of air traffic control, made worse by the lack of ground radar at Austin.
I’m looking forward to the final report.