LH 747 missed Mexicana A 320
 

From aviation safety network

24 OCT 2002 A Lufthansa Boeing 747-400 reportedly missed a Mexicana Airbus A.320 by some 30m while on approach to Mexico City Airport, October 7. The Lufthansa pilot ignored contrary orders from air traffic control and followed his TCAS RA to climb. (AFX)

Seems they did a good job.

If they ended up with 30 m separation , either TCAS or one of the crew did not do a very good job. I would love to know more about this incident, as we are currently evaluating TCAS limitations.

Lufthansa: Jet Nearly Collided With Air Mexicana Plane
Thursday October 24, 3:13 pm ET


FRANKFURT (AP)--A Deutsche Lufthansa AG jet narrowly avoided colliding with an Airbus operated by Airline Mexicana de Aviacion SA, as it came in to land in Mexico City, the German airline said Thursday.


The incident occurred as Lufthansa's Boeing 747 with 388 passengers on board approached the airport Oct. 7, said Lufthansa spokesman Michael Lamberty.

According to a report in German news magazine Stern, the Lufthansa pilot pulled the aircraft up sharply after the jet's onboard warning system sounded, ignoring instructions from Mexican air-traffic control. An Air Mexicana Airbus A320 with 120 passengers on board passed just 30 meters below, the magazine said. Air Mexicana is a unit of Mexican airline-holding company Cintra SA .

Lamberty declined to comment on the magazine's account, referring to an investigation of the incident by Mexican and German flight-safety authorities.

German authorities are still investigating how two jets collided above Germany in July, killing 71 people. One of the pilots had followed the urgings of air- traffic control to descend rather than instructions from the on-board warning system to climb.

Stern piece in German: http://www.stern.de/politik/news/artikel/?id=325100

Are ATC controllers receiving an on-screen warning that a TCAS RA has been issued ? And if so, why do they continue to separate the aircraft, possibly contradicting instructions pilots are receiving from their TCAS. :confused:

As far as I know, ATC is not automatically informed about TCAS resolutions. Therefore, the phrase "TCAS climb/descent" is usually issued by the affected pilots to clarify their actions.

The problem with disaccording instructions is the response time of TCAS (45 sec TA, 20-30 sec RA) plus the usual time lag in RT communications.
ATC might just have worked out some own way to resolve the situation when at the same time TCAS issues a different instruction.
So there's ATC telling you to descend and your TCAS telling you to climb (that's what happened in germany). Since both do not know of the other, you have to choose... and since TCAS' informations are usually more up to date (up to second would better describe it) plus TCAS issues coordinated (with the system of the other aircraft) resolutions only, it's always my choice.

Didn't we go through all this in "Mid-Air over Germany"? Seems to me that the same thing almost happened but people were lucky this time. Probably had a beer or two in the pub afterwards though.

7th October
 

And the first post is on the 24th in Stern.........

I think we should hang our heads in shame, we are not doing Danny's bidding here if we take 17 days to get something on this site, when a lot of you are really at the source of the possible rumours and info.

The Stern article clearly states that the LH & German rules are TCAS knows better - and after recent history, that seems the best advice. Sounds hard on ATC but if the systems could be improved so that hitting a panic button would disengage the AP and do TCAS's bidding as well as send a message to the ATC that pilot is following TCAS instructions.... things could be expected to be avoided most of the time I would have thought. Or is that just too logical.

Glad they missed though, look forward to the enquiry report.....:)

XPDR Auto-squawk for TA and RA
 

That's three incidents now on record where TCAS RAs conflicted with ATC -- JAL the other one.

While the TCAS electronics seem to be doing the job, it looks to me that the ATC human factor has been left out of the design consideration.

It's natural for ATC to get seriously concerned when targets are about to converge on the scope and it's 50/50 that ATC instructions at this point may aggravate the situation, but they have no confirmation that TCAS has taken over. Also crews responding to an RA don't have the time to discuss the situation.

What TCAS should also do is issue different squawk codes for TA and the various RA commands (increase/decrease/halt climb/descend) so that ATC knows what the a/c are up to.

There will still be an up to 10 second delay between radar sweeps, but at least ATC will be notified reasonably soon that they should not interfere with the TCAS resolution.

The first thing we ATCO's know about TCAS advisories and resolutions is when the pilot tells us. At our unit, the controller will be alerted to an impending loss of separation by the STCA (short term conflict alert) but this is a totally separate system from TCAS. It is possible that they may become linked at some time in the future but they certainly are not at the moment.

(This Mexican airprox appears to have taken place on approach and the aircraft may have been controlled by the tower visually so there would be no STCA, even if it is available in Mexican ATC.)

Once a controller becomes aware of an impending loss of separation, he should give avoiding action based on what he sees on his display. As the display lags behind 'real time' by a number of seconds, the pilot may well be taking his own separation based on his TCAS warning which could be exactly opposite to what the controller advises.

At my latest safety training, we were advised that in the light of the Swiss mid-air, avoiding action is best given in plan rather than vertically. In effect, we give a turn, TCAS gives climb/descent. Of course, every incident is different and it can be hard to generalise but we are, in the UK at least, aware that pilots will obey the TCAS no matter what we say.

Don't hold your breath. I've never seen anything 'official' come from Mexico, although I am out of the loop. Since all we have so far is media reports, I'd be inclined to take the 30m figure with a grain of salt.
Unless anyone knows more.....

Does it says anywhere whether the Mexicana crew maneuvered following or opposite their RA? Could also be a factor in the scant separation.

For those scratching heads have alook at the safety flash here
http://www.eurocontrol.int/acas
says it all

This is so sad ...
 

… but also so typical for my country.

First, the radar coverage within MEX is not very good. I used to fly regulary into MMMX and you always had to watch out for the helicopters that are flying close to the airport. They are below 500ft agl and cannot be seen by radar. At what altitude did this happen and what runways were in use at MEX?

How true. If you would now what I have seen in the cockpits of MX (even after 11 Sept) when I worked for them and their selection process. I have seen so many cover-ups when I worked with them … sorry, can’t say too much. Am glad to fly for other peoples. Surprised they are still in the star alliance…

High Tech airplanes for an airline below standards. It doesn’t work and never will…

The final report will be full of blabla and "no se" like all the other investigations related and unrelated to aviation.

Hola Capitán 104! Cómo estas? Email me, if you need more info...

How come we hear so late about this?

Possibly because it was a non-event ? Wouldn't be the first time some 'reporter' has failed to grasp that airspace is three-dimensional.

Report:"The airplanes came within 1 mile laterally and 30m vertically of each other"
Journo (thinks):"Blimey ! Buzzed him at a mile then had another go at 30m".

more than a non-event?
 

LH498 (B744) was approaching MEX on 7th oct at 1835 local time under ATC control (App or Twr?) in a descent passing about 3500 ft AGL. They received a TCAS "climb" resolution caused by an intruder approaching from one side. FO as PF pulled up and the Captain as PNF informed ATC. Apparently ATC grunted back they should resume normal descent immediately. Crew ignored this and right than slightly below passed the Mexicaca A 320. even visible in poor vis.(haze or clouds or mixture of)
Obviously the local authorities considered this incident as a minor event not worth to be noted or reported. LH safety experts in MEX are trying to get more light into this incident.

These are highlights translated from the magazine DER SPIEGEL.
Rather reliable and close to other infos available to me.
http://www.spiegel.de/spiegel/vorab/...220069,00.html

MateoSix
Hello, meanwhile I know what is typical for your country. It helps to know that some people try to warn. ;)

Well this is how google translated an excerpt from the newspaper article Although obviously this should not have happened, unless/until I see something from a more authoritative source (BFU ?), I'll reserve judgment.

What does "so ein Lufthanseat" really translate to ?

I hate to react on newspaper accounts, even if Der\Spiegel is a rather " serious" magazine but the article is probably based on second hand info as I doubt they interviewed the crew directly,and even if they did ,I doubt the magazine has someone who knows enought about the system to write something coherent.
As long as we do not have more details such as : exact Altitude at which this happenned, ( to determine which CAS logic applied ) total vertical manoevre of the 747 and eventual coorinated Ra of the A320 ( to exclude crossing RAs), what was the original ATC clearance to both aircraft , etc.. it will be difficult to discuss the case in a rational way.

Mention of radar sweep time earlier in the thread.

I understood that European rules limit this to 8 secs. Could anyone confirm ?

If I recall, part of the initial German mid-air investigation picked up on the fact that the Swiss ATC radar was still over the 8 sec sweep limit and was to be upgraded.

"Der Spiegel" is a rather serious magazine, but articles about aviation are sometimes really rubbish and highly laughable. Don't want to comment about this particular incident but in my opinion "Der Spiegel" reflects very well the low overall knowledge of aviation matters in Germany.