TCAS averts possible head-on collision in Austin
flightradar24.com
flightradar24.com
You can read all about the threat resolution logic in section 3.10.8 of ICAO 9863.
An aside:
> 3.10.1.1 The ACAS algorithms operate in a cycle repeated nominally once per second. At the beginning of the cycle, surveillance reports are used to update the tracks of all intruders and to initiate new tracks as required. Each intruder is then represented by a current estimate of its range, range rate, altitude, altitude rate, and perhaps, its bearing. Own aircraft altitude and altitude rate estimates are also updated.
Words that should probably never appear in technical specifications: "perhaps".
https://en.wikipedia.org/wiki/Traffic_collision_avoidance_sy...
I am unsure what it would have told them to do in the RA case though.
Edit: never mind the last bit, RAs actually get completely suppressed if GPWS does its thing, TAs still go through.
https://en.wikipedia.org/wiki/Traffic_collision_avoidance_sy...
Unfortunately we have thousands of airplanes that do not have electrical power so it would be very difficult to require it everywhere within the US.
ADS-B is better than nothing, but all it does is report where another airplane claimed to have been about 20-30 seconds in the past.
Flying formation with people while watching their ADS-B return is very illuminating.
Having TCAS in small GA airplanes is never going to be possible. The cost is too high and the performance differences are too great. You don’t need an RA to make a decision, TAs are completely sufficient in GA and ADS-B works quite well for that.
Not sure why you would care about this while flying formation. TCAS isn’t helping you there either.
https://www.researchgate.net/publication/343689163_A_study_o...
But, I believe it disables below 1000f above ground. And, we’ve seen many issues recently with aircraft on or near the ground - from the collision in Japan to many near-misses on the ground.
So, how might we make a system as robust as TCAS for aircraft on or near the ground?
I thought that was literally the entire reason we have controlled airspace rules?
The real question here is, why does Austin Approach Control have airliners driving around lower than the ceiling of the Class C protected airspace, where EVERY pilot knows that there are little putt-putt planes pottering about down there?
It definitely strikes me as a place that wouldn't be a great idea to fly your plane past if you're not planning to be on comms with ATC.
Did you know that there is a "tunnel" of uncontrolled airspace directly about Los Angeles International, between 3500 feet and 4500 feet, and you can fly through with commercial airliners whizzing about, talking to absolutely no radar services or ATC controllers? Called the LAX SFRA.
https://www.aopa.org/advocacy/advocacy-briefs/air-traffic-se...
How does one find a map?
https://www.faa.gov/air_traffic/publications/atpubs/aim_html...
Respectfully, you are incorrect, and if you are a pilot, this is a dangerous misunderstanding. ATC does NOT provide radar separation services between VFR and IFR aircraft in Class E airspace. Reference the AIM, section 3-2-6-(f). Only separation between IFR aircraft is provided, and you may or may not get advisories and vectors for VFR traffic. How could it be otherwise, technically? The VFR aircraft may not even be equipped with a transponder, one is not required if you are more than 30 miles away from one of the 30 major Class-B airports in the country, and it might be made of bamboo and cloth with negligible radar cross section, so ATC may not even be aware of it's existence.
Separation between IFR and VFR aircraft in Class E airspace requires see-and-avoid by both the IFR aircraft and the VFR aircraft, and it is the responsibility of both pilots in command to ensure this happens. That's why we have the visibility and speed limitations that we have in Class E airspace, to provide enough time and distance for see-and-avoid to occur. But it requires at least one person in each flight deck to have their eyes out the window, not face down looking at the fishfinder.
There has grown a culture of complacency at the major airlines when it comes to integrating with parts of national airspace system that are outside of being directed by a controller - witness the recent Southwest debacle where they took off from a closed runway with personnel working because they did not understand, did not know, or ignored the standard dispatch procedures for operating before a control tower opens.
1. Uncontrolled aircraft stay in uncontrolled airspace, airliners generally stay in controlled airspace (speaking generally, I know class E is controlled, but it's not positive control, and I know that the class C doesn't extend up to the class A) (successful)
2. The airliner had TCAS, as required, and the small plane had a working transponder, as required. As long as the airliner followed the RA, they would remain safe (successful)
3. The controller was supposed to provide separation on a workload permitting basis (not fully successful, the goal is more separation than was provided).
The ultimate result though was that the two planes missed each other by a fairly comfortable margin. The great thing is that the system doesn't depend on everyone being perfect to have a safe outcome, and it's been many years since an airliner has hit another plane in the U.S.
It's a choice to fly your airplane across the land/takeoff trajectory for a major airport. They also essentially flew by the F1 track on the way.
No, it isn't. It's a small non-jet aircraft. https://en.wikipedia.org/wiki/Cessna_182_Skylane
> they clearly weren't listing to ATC
They are not required to in that airspace at that altitude.
No, it isn't. You can get a Cessna for less than a Cybertruck. You cannot get a private jet that cheap.
> If you're flying a couple miles away from a commercial airport and across the path of the runways, maybe you're not required to be listening to ATC, but that's definitely a choice you're making to risk it.
There's an explicit system of controlled airspace around airports.
See the picture illustrations in https://aviation.stackexchange.com/questions/97110/why-do-ai...
The Cessna was operating in airspace it had the legal right to be in and no need for ATC coordination. Near some of the busiest airports, etiquitte requires you try not to make a nuisance of yourself as a GA pilot to ATC.
It's not as if the lack of literal jet engines makes it less of a problem or less of a rich person's toy.
ATC had this controlled aircraft outside the airport's standard controlled airspace.
The fact that TCAS occurred at all means the Cessna was properly (legal requirement) broadcasting its altitude, airspeed, and GPS position to all around it.
The blame here likely lies with ATC, not the Cessna pilot.
edit: Flight tracks and ATC comms at https://x.com/flightradar24/status/1847148742882857191. This was ATC's problem.
Words matter.
The Cessna pilot is under no obligation to maintain contact with ATC in this airspace, and it is the job of ATC to route the aircraft under its guidance around this kind of airspace, and if penetration of uncontrolled airspace is required, then to advise about and route around any known traffic.
The Cessna was probably communicating with the relevant CTAF or tower frequency for the airport it was setting up an approach for, or monitoring Unicom for traffic avoidance for other small VFR aircraft.
A single pilot can’t fly, navigate, and maintain traffic separation in a plane and communicate on all frequencies at once simultaneously, and ATC does not have the resources to control all random manoeuvres of small aircraft.
This is why there are places where small aircraft operate, mostly under “see and avoid” VFR rules, and places where all operations are done under strict ATC controls.
In this case, the heavy aircraft was directed to fly through one of these uncontrolled areas, and the controller failed to maintain adequate separation from uncontrolled operations.