Moderators: jsumali2, richierich, ua900, PanAm_DC10, hOMSaR

 
sonicruiser
Topic Author
Posts: 921
Joined: Sun Nov 04, 2018 4:18 am

18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Tue Jan 29, 2019 10:20 pm

Few people know about the JAL 747 and DC10 incident above Suraga Bay on January 31, 2001 mainly because it didn't happen. Due to some quick thinking and heroic save by the pilots of the 747, it resulted in only a few injuries on the 747 but little more. It was the accident that wasn't, a near miss that was 10 meters away from being the deadliest air accident of all time surpassing the Tenerife disaster. The cause was ultimately found to be an error resulting from ATC instructions and the resulting miscommunication.

https://www.japantimes.co.jp/news/2001/ ... -disaster/

https://www.youtube.com/watch?v=t9tz3cw1_mk
شما می توانید مردم را تحریم کنید ، اما نمی توانید سبک تحریم را اعمال کنید

You can sanction people, but you can't sanction style
 
AirCanada777X
Posts: 18
Joined: Tue Jul 10, 2018 5:02 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert disaster by just 10 meters

Tue Jan 29, 2019 10:30 pm

The DC10 was JAL Flight 958, and the 747 was JAL Flight 907.

Flight 958
DC10-40
JA8546
250 occupants
13 crew
237 passengers
0 occupants injured

Flight 907
B747-400
JA8904
427 occupants
16 crew
411 passengers
100 occupants injured
 
AWACSooner
Posts: 2539
Joined: Tue Jan 22, 2008 12:35 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 1:34 am

And THAT is why you should listen to TCAS vs the controlers.
 
User avatar
Stitch
Posts: 27167
Joined: Wed Jul 06, 2005 4:26 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 1:49 am

AWACSooner wrote:
And THAT is why you should listen to TCAS vs the controlers.


Indeed. And a year later the 2002 Überlingen mid-air collision would happen.
 
ryanov
Posts: 236
Joined: Sat Nov 03, 2012 4:38 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 2:05 am

I know that this is why TCAS takes precedence, but is there anything that prevents ATC and TCAS from issuing conflicting instructions? I suppose what's supposed to happen generally is that the conflict is supposed to be dealt with before an RA is necessary?
 
eamondzhang
Posts: 1799
Joined: Thu Sep 23, 2010 8:23 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 2:14 am

Stitch wrote:
AWACSooner wrote:
And THAT is why you should listen to TCAS vs the controlers.


Indeed. And a year later the 2002 Überlingen mid-air collision would happen.

And one reason why Uberlingen happened was because (apparently) the recommendation from this incident wasn't taken seriously and in time.

Michael
 
BoeingGuy
Posts: 6313
Joined: Fri Dec 10, 2010 6:01 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 3:09 am

AWACSooner wrote:
And THAT is why you should listen to TCAS vs the controlers.


Yep, current industry guidance is to follow TCAS over anything. It’s proven it’s reliability and there might be another airplane that you don’t see.
 
MalevTU134
Posts: 2188
Joined: Tue Oct 11, 2016 8:04 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 6:08 am

Question for pilots on here: What has always baffled me is why in these cases, when some algorithm (I suppose that is how it works?) predicts that your plane and another plane will be at the same place at the same time, TCAS does not intend to achieve maximum separation by not only separating in one dimension, but in two. In other words, if the two planes are on a head-on collision course (the simplest example, I guess), why it isn't "CLIMB AND TURN RIGHT" and "DESCEND AND TURN RIGHT", rather than just "CLIMB" and "DESCEND" in the two respective aircraft. In this way, if only 1 out of 4 commands are abided by, collision is avoided. Is there any reason why this isn't so? Or are there instances when TCAS does indeed issue 2-dimensional "escape routes"?
 
User avatar
BlueSky1976
Posts: 1890
Joined: Tue Jul 20, 2004 9:18 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 6:50 am

...because when miliseconds decide between life and death, a simple "CLIMB" and "DESCEND" works much better.
The queen of the skies is dead.
 
MalevTU134
Posts: 2188
Joined: Tue Oct 11, 2016 8:04 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 6:57 am

BlueSky1976 wrote:
...because when miliseconds decide between life and death, a simple "CLIMB" and "DESCEND" works much better.

Is it really milliseconds, though? Doesn't TCAS gove you more advance warning than that? Milliseconds, come on, pilots are great guys and gals, but no supermen (or -women)...
And as I said: as long as only any 1 command in either of the planes is followed (be it either CLIMB or TURN LEFT (even if preferably both)), collision is avoided.
 
User avatar
Lingon
Posts: 113
Joined: Sun Sep 03, 2017 4:18 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 7:41 am

Personally, I think the most baffling is that the TCASes in two planes are able to negotiate safely at all times. If you have two aircraft flying level at the exact same altitude with crossing paths, there must be somethhing in the system to decide who should climb and who should descend. In a head-on case, this must be done fast.
I made a quick search som time ago to find out more about the algorithm for this, and found a huge thing which I didn't have the time to digest. Seemingly it was very elaborate.
 
User avatar
BlueSky1976
Posts: 1890
Joined: Tue Jul 20, 2004 9:18 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 12:15 pm

MalevTU134 wrote:
BlueSky1976 wrote:
...because when miliseconds decide between life and death, a simple "CLIMB" and "DESCEND" works much better.

Is it really milliseconds, though? Doesn't TCAS gove you more advance warning than that? Milliseconds, come on, pilots are great guys and gals, but no supermen (or -women)...
And as I said: as long as only any 1 command in either of the planes is followed (be it either CLIMB or TURN LEFT (even if preferably both)), collision is avoided.


It's not about the time of warning, it's about human reaction time to the warning in trained environment. Must be instant. Hence why "CLIMB" and "DESCEND" are best and proven solutions. Anything more than that creates unnecessary delays where miliseconds can decide between life and death.
The queen of the skies is dead.
 
User avatar
Stitch
Posts: 27167
Joined: Wed Jul 06, 2005 4:26 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 4:54 pm

ryanov wrote:
I know that this is why TCAS takes precedence, but is there anything that prevents ATC and TCAS from issuing conflicting instructions?


No. As such (per the Wiki article), once TCAS announces a Resolution advisory, the pilots are supposed to ignore ATC instructions and comply with the TCAS instructions until TCAS declares a Clear of conflict, at which point the pilots inform ATC and resume being under their control.
 
User avatar
AirlineCritic
Posts: 1765
Joined: Sat Mar 14, 2009 1:07 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 10:19 pm

I did not know of this incident. Thanks for posting!

TCAS is one amazing piece of engineering, btw.
 
Flow2706
Posts: 240
Joined: Sat Jan 28, 2017 7:20 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 10:34 pm

MalevTU134 wrote:
Question for pilots on here: What has always baffled me is why in these cases, when some algorithm (I suppose that is how it works?) predicts that your plane and another plane will be at the same place at the same time, TCAS does not intend to achieve maximum separation by not only separating in one dimension, but in two. In other words, if the two planes are on a head-on collision course (the simplest example, I guess), why it isn't "CLIMB AND TURN RIGHT" and "DESCEND AND TURN RIGHT", rather than just "CLIMB" and "DESCEND" in the two respective aircraft. In this way, if only 1 out of 4 commands are abided by, collision is avoided. Is there any reason why this isn't so? Or are there instances when TCAS does indeed issue 2-dimensional "escape routes"?

It takes much longer to establish lateral separation compared to vertical. Also at high levels the risk of loss of control is increased by a turn if the maneuver is executed improperly. The was an incident in a company that I was working for previously where a crew reacted to a "turn left HDG XYZ immediately" given by ATC at high level (FL350+) with a turn exceeding 45° of bank angle. Alpha protection kicked in (aircraft involved was an A320) and reduced the angle of attack, thereby keeping the aircraft from stalling and keeping this from becoming a major incident/accident. Later on the procedure was changed so avoidance maneuvers by ATC would be flown with Autopilot on and Autopilot should only be disconnected during these maneuvers if the response of the AP was inadequate. If you now combine a turn and climb at high levels a startled crew will eventually stall the aircraft and cause an serious accident/incident.
Lateral separation is also more complex and requires a more complete picture of the traffic situation. If you turn on aircraft right for a couple of seconds it will maybe get into conflict with an other aircraft further down route, so the work load for the ATC will be even more increased to return everything to "normal" after the RA. For a vertical maneuver it is sufficient most of the time to return the involved aircraft to the original level.
 
LH707330
Posts: 2343
Joined: Fri Jun 15, 2012 11:27 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Wed Jan 30, 2019 11:39 pm

MalevTU134 wrote:
BlueSky1976 wrote:
...because when miliseconds decide between life and death, a simple "CLIMB" and "DESCEND" works much better.

Is it really milliseconds, though? Doesn't TCAS gove you more advance warning than that? Milliseconds, come on, pilots are great guys and gals, but no supermen (or -women)...
And as I said: as long as only any 1 command in either of the planes is followed (be it either CLIMB or TURN LEFT (even if preferably both)), collision is avoided.

Turning wouldn't really add much to the equation for a variety of reasons:

1. Initiating your turn requires two steps, bank and back pressure, versus just dive or climb, which adds time.
2. The target you're avoiding is flat (tail shorter than span/length), and you're flat, so the best way to avoid contact is vertical separation. Banking just makes the targets bigger.
3. It's a shorter, easier command to follow.
 
User avatar
CarlosSi
Posts: 656
Joined: Sat Jul 08, 2017 8:29 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 1:08 am

Turning away is the aircraft collision equivalent of the Prometheus school of running away from things in the event the two aircraft are perpendicular in flight. You’ll have aircrafts cross paths which may not be favorable if wake is high (not sure how bad it is flying high and fast).
 
User avatar
September11
Posts: 3652
Joined: Fri May 21, 2004 12:49 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 2:09 am

This incident took place 8 months before 9/11... 2001 was't a very good year for aviation
Airliners.net of the Future
 
Antarius
Posts: 2421
Joined: Thu Apr 13, 2017 1:27 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 3:57 am

LH707330 wrote:
MalevTU134 wrote:
BlueSky1976 wrote:
...because when miliseconds decide between life and death, a simple "CLIMB" and "DESCEND" works much better.

Is it really milliseconds, though? Doesn't TCAS gove you more advance warning than that? Milliseconds, come on, pilots are great guys and gals, but no supermen (or -women)...
And as I said: as long as only any 1 command in either of the planes is followed (be it either CLIMB or TURN LEFT (even if preferably both)), collision is avoided.

Turning wouldn't really add much to the equation for a variety of reasons:

1. Initiating your turn requires two steps, bank and back pressure, versus just dive or climb, which adds time.
2. The target you're avoiding is flat (tail shorter than span/length), and you're flat, so the best way to avoid contact is vertical separation. Banking just makes the targets bigger.
3. It's a shorter, easier command to follow.


Good points.

Also to add to #3, the more complex, the slower the potential reaction and the higher the chance of a mistake.

Also TCAS seems to work remarkably well as is.
2020: SFO DFW IAH HOU CLT MEX BIS MIA GUA ORD DTW LGA BOS LHR DUB BFS BHD STN OAK PHL ISP JFK SJC DEN SJU LAS TXL GDL
 
USAirKid
Posts: 645
Joined: Mon Jun 13, 2016 5:42 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 4:26 am

MalevTU134 wrote:
Question for pilots on here: What has always baffled me is why in these cases, when some algorithm (I suppose that is how it works?) predicts that your plane and another plane will be at the same place at the same time, TCAS does not intend to achieve maximum separation by not only separating in one dimension, but in two. In other words, if the two planes are on a head-on collision course (the simplest example, I guess), why it isn't "CLIMB AND TURN RIGHT" and "DESCEND AND TURN RIGHT", rather than just "CLIMB" and "DESCEND" in the two respective aircraft. In this way, if only 1 out of 4 commands are abided by, collision is avoided. Is there any reason why this isn't so? Or are there instances when TCAS does indeed issue 2-dimensional "escape routes"?


I took a look at the FAA Description of TCAS the relevant bit is on page 34.
  1. Each plane’s TCAS determines its best response to the potential collision and transmits it to the other.
  2. If they agree they both tell their pilots to execute the maneuver.
  3. If they disagree, the proposed solution of whichever plane declared the other airplane to be an intruder first, is followed, and communicated to the pilots.
  4. If they both identified the other airplane to be an intruder at the same time, the solution of the one plane with the lower Mode S address will be followed.

The Wikipedia article provides additional information on why a horizontal collision avoidance maneuver isn’t provided, as it was studied for TCAS III. (The currently implemented TCAS version is II 7.1):

TCAS III attempts to use the TCAS directional antenna to assign a bearing to other aircraft, and thus be able to generate a horizontal maneuver (e.g. turn left or right). However, it was judged by the industry to be unfeasible due to limitations in the accuracy of the TCAS directional antennas. The directional antennas were judged not to be accurate enough to generate an accurate horizontal-plane position, and thus an accurate horizontal resolution. By 1995, years of testing and analysis determined that the concept was unworkable using available surveillance technology (due to the inadequacy of horizontal position information), and that horizontal RAs were unlikely to be invoked in most encounter geometries. Hence, all work on TCAS III was suspended and there are no plans for its implementation.
Last edited by USAirKid on Thu Jan 31, 2019 4:34 am, edited 1 time in total.
 
spahrtan
Posts: 21
Joined: Sun Jan 11, 2015 8:19 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 4:27 am

100 people injured on the 747? The maneuvers were that severe to injury nearly a quarter of the occupants? Incredible actions by the pilots to get their aircraft out of certain disaster, and hopefully those 100 people understood through their injuries how much worse it could have been.
 
boerje
Posts: 49
Joined: Tue Jan 09, 2018 9:16 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 11:39 am

spahrtan wrote:
100 people injured on the 747? The maneuvers were that severe to injury nearly a quarter of the occupants? Incredible actions by the pilots to get their aircraft out of certain disaster, and hopefully those 100 people understood through their injuries how much worse it could have been.


"Seven passengers and two crew members of the 747 sustained serious injuries; additionally, 81 passengers and 10 crew members reported minor injuries. Some unbelted passengers, flight attendants, and drink carts hit the ceiling, dislodging some ceiling tiles. The maneuver threw one boy across four rows of seats. Most of the injuries to occupants consisted of bruising. The maneuvers broke the leg of a 54-year-old woman. In addition, a drink cart spilled, scalding some passengers."

JAL907 injury chart in Wikipedia

2001 Japan Airlines mid-air incident in Wikipedia
 
User avatar
Lingon
Posts: 113
Joined: Sun Sep 03, 2017 4:18 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 12:00 pm

USAirKid wrote:
I took a look at the FAA Description of TCAS the relevant bit is on page 34.
  1. Each plane’s TCAS determines its best response to the potential collision and transmits it to the other.
  2. If they agree they both tell their pilots to execute the maneuver.
  3. If they disagree, the proposed solution of whichever plane declared the other airplane to be an intruder first, is followed, and communicated to the pilots.
  4. If they both identified the other airplane to be an intruder at the same time, the solution of the one plane with the lower Mode S address will be followed.


Thanks!
 
BritishB747
Posts: 244
Joined: Wed Jun 02, 2010 5:14 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 1:00 pm

The article states that the aircraft passed within 135 meters of each other, not 10 as the title of this thread suggests. Still very close though!
AT5 AT7 AB6 319 320 321 333 33V 343 346 AR8 733 734 736 73G 738 744 752 753 763 77E 77W 788 BET CR7 D10 D38 DHT DH4 E70 E75 E90 F70 J41 M83 S20 SF3
 
estorilm
Posts: 762
Joined: Fri Jan 16, 2009 3:07 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 2:57 pm

Stitch wrote:
ryanov wrote:
I know that this is why TCAS takes precedence, but is there anything that prevents ATC and TCAS from issuing conflicting instructions?


No. As such (per the Wiki article), once TCAS announces a Resolution advisory, the pilots are supposed to ignore ATC instructions and comply with the TCAS instructions until TCAS declares a Clear of conflict, at which point the pilots inform ATC and resume being under their control.

Wouldn't your answer be a "yes" then? It's prevented because pilots are drilled to listen to TCAS above all other factors and instructions, including ATC.

I've also heard controllers give traffic distancing instructions with the caveat to "follow TCAS RA if available" or something along those lines - which is assumed, but the controller was being clear on the matter. Same thing if a pilot calls in with a TCAS instruction to ATC.
 
FlyHossD
Posts: 2086
Joined: Mon Nov 02, 2009 3:45 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 3:30 pm

This reminded me a bit of a near midair collision between a 747 and a L1011 on the NAT tracks (I don't remember the year anymore, but well before this JAL incident)(and before TCAS, too). The crew of the L1011 (DL?) had requested a route change and then changed their route before receiving the clearance. The captain of the 747 didn't trust the "separation system" on the tracks and so, he always flew 100' high. The L1011 passed immediately below the 747.

BTW, I got this info directly from one of the 747's crew.
My statements do not represent my former employer or my current employer and are my opinions only.
 
Bambel
Posts: 133
Joined: Sun Jan 18, 2015 8:38 pm

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 4:51 pm

BritishB747 wrote:
The article states that the aircraft passed within 135 meters of each other, not 10 as the title of this thread suggests. Still very close though!


The 135m was calculated from the transponder response but it's only measured every second. Given the high lateral and in this case vertical speed of the involved aircraft it's likely that the closest point wasn't recorded. The 10m came from both crews.

b.
 
User avatar
Stitch
Posts: 27167
Joined: Wed Jul 06, 2005 4:26 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 7:51 pm

estorilm wrote:
Wouldn't your answer be a "yes" then? It's prevented because pilots are drilled to listen to TCAS above all other factors and instructions, including ATC.


Sorry. I interpreted your question as if their was a technical implementation to prevent conflicting instructions being issued.
 
estorilm
Posts: 762
Joined: Fri Jan 16, 2009 3:07 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 9:29 pm

Stitch wrote:
estorilm wrote:
Wouldn't your answer be a "yes" then? It's prevented because pilots are drilled to listen to TCAS above all other factors and instructions, including ATC.


Sorry. I interpreted your question as if their was a technical implementation to prevent conflicting instructions being issued.

No worries - wasn't my question.. just meant there's nothing technical that can know what ATC is thinking - but yes especially after that crash, pilots are DRILLED to listen to TCAS above anything else. If you get a really good controller, they'll also remind you to give priority to TCAS resolution advisories. :)
 
cedarjet
Posts: 8808
Joined: Mon May 24, 1999 1:12 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Thu Jan 31, 2019 10:53 pm

I wouldn’t trust 70% of airline pilots to safely execute a steep turn in the cruise with one second warning. And to prove the point, a 727 crashed with the loss of all onboard after just such a manoeuvre. Went supersonic just 17 seconds after the start of the event. 144 lives lost because of a near-miss. Climb/descent is many degrees of magnitude simpler.

https://aviation-safety.net/database/re ... 19961107-0
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
ryanov
Posts: 236
Joined: Sat Nov 03, 2012 4:38 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Fri Feb 01, 2019 7:57 am

Stitch wrote:
Sorry. I interpreted your question as if their was a technical implementation to prevent conflicting instructions being issued.


It was my question and you answered it correctly — not sure what the other guy was getting at.

Didn’t necessarily need to be technical though, as in maybe TCAS uses predictable logic or what have you. Would be good if a future system somehow provided a way to avoid conflicting instructions.
 
User avatar
AirKevin
Posts: 619
Joined: Wed Apr 26, 2017 2:18 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Mon Feb 04, 2019 12:17 am

estorilm wrote:
Stitch wrote:
ryanov wrote:
I know that this is why TCAS takes precedence, but is there anything that prevents ATC and TCAS from issuing conflicting instructions?


No. As such (per the Wiki article), once TCAS announces a Resolution advisory, the pilots are supposed to ignore ATC instructions and comply with the TCAS instructions until TCAS declares a Clear of conflict, at which point the pilots inform ATC and resume being under their control.

Wouldn't your answer be a "yes" then?

No. The question asked if there was anything that prevents ATC and TCAS from issuing conflicting instructions. There isn't anything stopping this from taking place since ATC has no idea what TCAS is telling the pilots.
Captain Kevin
 
estorilm
Posts: 762
Joined: Fri Jan 16, 2009 3:07 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Mon Feb 04, 2019 2:04 pm

AirKevin wrote:
estorilm wrote:
Stitch wrote:

No. As such (per the Wiki article), once TCAS announces a Resolution advisory, the pilots are supposed to ignore ATC instructions and comply with the TCAS instructions until TCAS declares a Clear of conflict, at which point the pilots inform ATC and resume being under their control.

Wouldn't your answer be a "yes" then?

No. The question asked if there was anything that prevents ATC and TCAS from issuing conflicting instructions. There isn't anything stopping this from taking place since ATC has no idea what TCAS is telling the pilots.

Well... the answer is still yes; all pilots are trained to take priority from the TCAS RA over anything ATC is telling them. That eliminates any possibility of a conflict right there. :)

Unless you're saying the very fact that two differing instructions were given in the first place - that can't be avoided but is also unimportant since ATC will be ignored.

Plus there are still situations where aircraft might not have TCAS, so it's still important for the controller to issue instructions regardless.

I honestly think it's one of the few systems in commercial aviation (critical / safety-wise) which has evolved from being non-existent to nearly-perfect in a fairly short period of time. Like most of these systems - once they are online, we will likely never really know just how many lives have been saved, other than observing how many weren't lost.
 
User avatar
AirKevin
Posts: 619
Joined: Wed Apr 26, 2017 2:18 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Tue Feb 05, 2019 3:04 am

estorilm wrote:
Unless you're saying the very fact that two differing instructions were given in the first place - that can't be avoided

Yes, that's what I am saying, as that was what the original question was asking. The person who asked the question is very much aware that TCAS takes precedence over ATC, so that wasn't the question that was being asked.
Captain Kevin
 
estorilm
Posts: 762
Joined: Fri Jan 16, 2009 3:07 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Tue Feb 05, 2019 2:10 pm

AirKevin wrote:
estorilm wrote:
Unless you're saying the very fact that two differing instructions were given in the first place - that can't be avoided

Yes, that's what I am saying, as that was what the original question was asking. The person who asked the question is very much aware that TCAS takes precedence over ATC, so that wasn't the question that was being asked.

Sorry for the misunderstanding - again though, I see absolutely zero way around that and it doesn't seem to be an issue now that things are clearly defined (internationally!) - maybe that's why I didn't understand the question in the first place.
 
User avatar
AirKevin
Posts: 619
Joined: Wed Apr 26, 2017 2:18 am

Re: 18 years ago: JAL 747 and DC10 narrowly avert catastrophe by just 10 meters

Tue Feb 05, 2019 2:30 pm

estorilm wrote:
AirKevin wrote:
estorilm wrote:
Unless you're saying the very fact that two differing instructions were given in the first place - that can't be avoided

Yes, that's what I am saying, as that was what the original question was asking. The person who asked the question is very much aware that TCAS takes precedence over ATC, so that wasn't the question that was being asked.

Sorry for the misunderstanding - again though, I see absolutely zero way around that

Yes, that's what I've been trying to say. ATC has no way of knowing what TCAS is telling the pilots, so there's no way to avoid getting conflicting instructions from ATC and TCAS. That's why TCAS takes precedence.
Captain Kevin

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos