View Full Version : LH 747 missed Mexicana A 320

24th Oct 2002, 18:14
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.

ATC Watcher
24th Oct 2002, 20:47
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.

Shore Guy
25th Oct 2002, 06:30
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

25th Oct 2002, 08:45
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:

25th Oct 2002, 10:14
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.

25th Oct 2002, 14:26
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.

25th Oct 2002, 14:40
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.....:)

25th Oct 2002, 20:29
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.

25th Oct 2002, 21:56
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.

25th Oct 2002, 22:00
look forward to the enquiry report..... 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.....

aluminum ovcst
25th Oct 2002, 22:06
Does it says anywhere whether the Mexicana crew maneuvered following or opposite their RA? Could also be a factor in the scant separation.

26th Oct 2002, 00:02
For those scratching heads have alook at the safety flash here
says it all

26th Oct 2002, 02:21
… 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?

Don't hold your breath. I've never seen anything 'official' come from Mexico

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...

26th Oct 2002, 02:54
How come we hear so late about this?

26th Oct 2002, 05:28
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".

26th Oct 2002, 13:05
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.

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

26th Oct 2002, 17:46
Well this is how google translated an excerpt from the newspaper article How close came themselves the machines this time, is uncertain, because the radar recordings of the incident are not yet evaluated. Nevertheless a crew member, such a Lufthanseat, could recognize the lights of the Mexicana jet despite poor visibility.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 ?

ATC Watcher
26th Oct 2002, 21:08
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.

26th Oct 2002, 21:43
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.

Burger Thing
27th Oct 2002, 01:48
"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.

27th Oct 2002, 08:10

"so ein Lufthanseat" translates into "according to a Lufthansa employee".


27th Oct 2002, 16:57
Thanks Hopper.

Well there you have it then. Unimpeachable source :rolleyes:

ATC Watcher
27th Oct 2002, 21:05
Lost luggage ; there is no standard radar return time. this depends on what kind of radar you operate . the rotation of the antenna will determine the range. In en-route operations , you need range . the majority of the radars have a 6 rpm or 10 seconds update. that will give you roughly 300 NM . In approach ops , where you need less range but need a faster refresher rate , you go to 10 rpm and have a 6 sec return rate.

In the case of Zurich, the referesher rate was 12 seconds.

the rooster
29th Oct 2002, 03:08
MEX terminal area is regarded as difficult, for good reason.
terrain, weather, atc, approach design, airspace congestion, lack of adequate infrastructure etc.
On the other hand, radar coverage is pretty advanced and air traffic controllers in general are good and particularly considerate to foreign carriers. Helicopters use their own visual corridors and remain below 500 ft.
Mexican professional pilots are most aware of this circumstances, as we fly in and out of mmmx every day.
Advice? trust your controller and limit your v/s 1000ft prior to level-off. If this should fail to do the trick, trust and follow your ra´s.
Mexicana de aviación pilots are proud to share Star Alliance with LH and our other partners. We earned our place there, unlike other people who are nowadays "flying for other peoples". Maybe there's a standard after all.
Mateo six: please share with us all those cover-up stories you have cracked!
I'd wait for some intelligent info on this near-miss incident.
if I have it fist i´ll let you know.

30th Oct 2002, 01:35
Sr. gallo:

The standard in “Compania Mexicana de Aviación” is that primarily of nepotism and dangerous machismo. A little intro:

Poor general knowledge of aircraft, procedures and ops,
f/a practicing (you know!),
Looking at most new-hires after 97/98 I don’t think that there’s a standard after all: Mostly under-qualified new pilots (entry tests are much easier when daddy’s got access to them, etc.)

I think MX earned its place in our typical Mexican wey…

Proud? Of what? Certainly not safety…
Email me, I will not say more here.

Too bad I don’t really exist any more, I should be Otumba now... ;)


30th Oct 2002, 08:24
Thanks ATC Watcher - most informative.

1st Nov 2002, 20:57
Another incident involving TCAS and a loss of separation took place in Canada on 13 July 2001.
The Transportation Safety Board of Canada recently released its final report (A01C0155) and made this finding: "Risk of collision was increased because TCAS and air traffic control are not coordinated. Each flight crew independently decided to disregard the TCAS resolution advisory commands because they were contradictory to instructions the controller had already issued."

The report also said that "On 27 September 2002, Transportation Safety Board sent an Aviation Safety Advisory (615-A020026) to Transport Canada suggesting that they may wish to review current regulations and TCAS guidance material with a view toward developing clear procedures to prevent a risk of collision in the event of conflict between ATC instructions and TCAS RA commands."

This conflict between TCAS commands and ATC instructions is also addressed in FAA Advisory Circular 120-55B which is available in PDF format at this link: FAA AC 120-55B - Air Carrier Operational Approval and Use of TCAS II (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/ACNumber/0C02E3D02AD4011786256C1400632EF7?OpenDocument)

Bottom line? TCAS is the final line of defense. Follow your RA!

2nd Nov 2002, 17:47
suggesting that they may wish to review current regulations and TCAS guidance material with a view toward developing clear procedures to prevent a risk of collision in the event of conflict between ATC instructions and TCAS RA commands
Sounds like Sir Humphrey bluddy Appleby :mad:

7th Nov 2002, 02:35
A few thoughts have crossed my mind about this thread ...

It seems that some pilots who posted their remarks know more than they are allowed to say, some obviously being rather bitter it seems ...

One thing that catches my attention is that this incident is being investigated because of Lufthansa 's request. From the report of Der Spiegel one gets the impression that neither Mexican ATC nor Mexicana seemed to be bothered by this and did not report it to the responsible authority to be further investigated. If this is true then ... :eek: :confused:

A question for ATC Watcher or other controllers:

If there is a "near-miss" in your airspace or a flight crew follows their TCAS RA, are you (as an air traffic controller) required to submit a report?

Captain 104 :

Will the final report be officially published by Lufthansa or the LBA?

7 7 7 7

7th Nov 2002, 16:22
Correct me if I'm wrong but I thought that mode s was supposed to send the data up and down the link. I'd sort of assumed that the ATC rad would show an TA/RA indication through that?

Maybe mode s is not as widely used as I thought?

7th Nov 2002, 17:49
Hello SQUAWk7777

To answer your question:
1)LBA( or BFU) I don't know.
2)DLH safety department CF definitely yes(cockpit crew info only).
Just my guess.

Some facts:
CF published the incident for internal info to cockpit crews in the briefing room in FRA some days after it happened.
I never did and never will publish internal info from a company in PPRuNe. For nearly 2 weeks nothing in the media.
On 24th Oct. the german magazine DER STERN published a breathtaking version( pilot pulled rapidly....). That is the magazine which published Hitlers falsified diary years ago and not very trustworthy.
AIR SAFETY NET followed in moderate style and in english.
2 days later the magazine DER SPIEGEL published a version so
close to facts and the official LH report that one could think they are very well informed.

There is room for speculation:
Since LH for sure considered the incident as serious as we would expect ( why should they send their experts to MEX?) and at the same time mexican authorities kept more than quiet: could it be that someone tickled the press to overcome mexican resistance to mention or even talk about it? :confused:

Amazing: still today no one talking or writing about an incident which is to be classified according to my information as serious and for sure more than a "non-event". :(

7th Nov 2002, 18:48
How come the tail didn't come off? :D

ATC Watcher
7th Nov 2002, 19:09
in reply to questions :
7777 : an airprox filed by a crew will of course be logged by ATC and investigated by the authorities responsible for ATS at the time the incident occurred. So if an airprox has been filed by either DLH or MEX, an investigation will be made and a report will be made . That report will be sent to the safety dept of the airline(s) involved and the ATC facility involved . That is what the (ICAO) book says. Some States (e.g UK) go further and really make public SOME of the airprox investigations reports.
I doubt very much that Mexico Civil aviation authority will do so ( but I might be wrong )
A TCAS RA deviation will only be logged if it interferd with ATC or is abnormal in nature ( like the many RAs caused by ghost tragets for instance ) Some States ( or Eurocontrol in Europe ) have special forms for this that are centralised and investigated ( Bretigny is doing this for Eurocontrol member states for instance )
A TCAS RA that results in a loss of separation will not necessarily result in an airprox being filed , especilally if the "error" is made by one of the crews ( e.g over-reaction to an RA , a very frequent case ) as an airprox can only be filed by aircrew.
ATC should in that case log the loss of separation on the TCAS report and on their logs. What happens further depends on the safety culture of the place. Again the UK and the USA for instance have firm procedures for this, but they are the very minority unfortunately.
Not knowing what really happenned in Mexico, the above is only generic info of course.

Quack driver : It is quite complex but the quick answer would be : Mode s transponders broadcast altitude that are picked up by TCAS. They do not broadcast RAs to be picked up by the ground. From a world wide perspective , very few ATC centres have acess to mode S or use Mode S. Of those only a couples ( e.g Miami in the US or Maastricht in Europe ) have a data link receiving capability. TCAS RAs ( or Altitude ) is not (yet) part of the grounds receivers capabilites.

Capt 104 : Since you seem to have access to the original DLH/CF data , can you check that the DLH crew stayed within RA max deviation ( i.e max 400ft from asigned Alt ) if they did not that could explain the sequence of events and the controller reaction )

7th Nov 2002, 19:30
Perhaps they had loaded a ton of viagra?:D

ATC Watcher:
Will try find out. At present time no idea.


8th Jan 2003, 19:19
Found this today in an official Bulletin on the BFU-website:
http://www.bfu-web.de/Bulletin/Bulletin0210.PDF on page 6 only in german.

The reason I would like to revive this thread is to quote the mexican duty supervisor: "IN THE APPROACH SECTOR OF MEX DO NOT FOLLOW TCAS COMMANDS." Nice statement and worth some discussion.
Try to translate highlights:

On flight FRA to MEX 7th Oct. 2002 occured a dangerous airprox. On board of B747-400 were 388 PAX and 19 crew.
Planned was an ILS DME #2 for RWY 05R i.e. approach via VOR PACHUCA (PCA) to LUCIA(SLM) and than MATEO(SMO) with a left turn to ILS 05R. Due to TS returns on WX radar between MATEO and Mexico City, LH Cpt. asked for direct course to MEX VOR and than an ILS DME #1 approach to avoid thunderstorms. Controller refused request, so they continued to MATEO. Controller ordered step descends to 13000', than to 12000' and finally to 11000'. Just prior reaching MATEO passing 11800' the crew noticed an AC on TCAS left in 10 o'clock position about 600' lower approaching rapidly. TCAS indication changed quickly from white to yellow with TA "traffic traffic." Immediately followed a RA (resolution advisory) "climb climb." FO as pilot flying reacted immediately and initiated a climb. The flight path of both AC crossed. According
to LH cockpit crew the vertical distance was about 100'.

The Cpt. called MEX approach and reported "TCAS climb". The controller answered "negativ climb, hold altitude due traffic". He repeated this 2 times than said "continue approach." On request of ATC the approach was discontinued. The AC was now send to OTUMBA first, than to MEX VOR to enter the hold. The LH crew indicated their decreasing fuel reserves and and received a clearance for an uneventful approach and landing.

After landing the crew had a conversation with the "Duty Supervisor" of MEX ATC. He declared that a mexican AB 320 on another frequency had received a descend clearence to 11000' and a left turn to MATEO VOR. The mexican Airbus followed this command very slow, which caused the airprox. The LH crew followed the TCAS RA contradictory to orders of ATC.

According to the mexican "Duty Supervisor" in the approach sector to MEX there is a rule:"DO NOT FOLLOW TCAS COMMANDS."
The evaluation of CVR indicated that RT communication around MEX was mainly handled in spanish language. Only foreign AC were handled in english. At the time of the incident the frequency was quite busy........
The ATC tape with communication between A 320 and controllers is not available.... CVR or FDR of mexican A 320 is not available to BFU.

Please excuse my goofy pidgin english. What do you think? :confused:

ATC Watcher
8th Jan 2003, 20:26
Capt 104 ; the BFU unfortunately only reports the facts as reported by the DLH crew + data collected on the 747.
The Mexicans have another story, but not official yet, so difficult to argue their case .
I hesitate to post their version on the net .
Let's say that the interesting points to be looking for would be :
Did the MEX A320 received a heading and did not comply ?
Was the rate of decent of the A320 in excess of 4000 ft/min ?
Did the MEX A320 had its TCAs on ?
Was the actual minimum lateral distance in excess of 2NM ?
Was the 3rd aircrfat involved 1000ft above the 747 and what was his transponder ?
Was the holding full due Cbs over the field ?
From what I read, and if it is confirmed officially, the R/T reaction of the controller could be well justified.
But I find the remark of the Mexican ATC supervisor astonishing . I guess (hope ) some language / communication problems might be at the source of that statement.
As to the R/T, well in Mexico spanish is the official R/T language.
in any case the A320 was in another frequency, so the 747 would not have heard the original clearance, and should it had, and it had been in English, it would not have meant much to the 747 anyway.

8th Jan 2003, 21:26

According to the Mexican "Duty Supervisor" in the approach sector to MEX there is a rule: "DO NOT FOLLOW TCAS COMMANDS"

What an un believable statement! If this person meant to say what is translated here, then he has put himself in an indefensible position. What for?

Cap 104:

I flew all over Mexico for 4 years and I can tell you that I NEVER EVER heard of any such rule. Just the thought of it is ridiculous.

Mexico follows ICAO's procedures and if a report of a Nearmiss was filed by Lufthansa I'm sure The DGAC (Mexico's CAA) will have to come up with a response and carry out an investigation of their own. It may take longer than it would in Germany that's for sure.

In all Mexican Operator's training and operating cultures TCAS RA's are perfectly understood. If the situation had been reversed, the Mexicana would have followed his RA too.

You should go back a little bit on this thread and read The Rooster's post.

Since the statement has been translated from Spanish to German and on this thread onto English, I have to think that something got lost...

ATC Watcher claims to know the Mexican version...What's with all the secrecy?

8th Jan 2003, 23:52
"Do not follow TCAS commands" is not a translation.

While the report is written in German, this quote is given in English on page 6. My surmise is that the conversation with the ATC Duty Manager was conducted in English.

9th Jan 2003, 03:49
ATC watcher:
Fully agree with your questions concerning A 320 involved. Have still no access to any statement by mexican officials but it seems that language problems refering to the duty managers statement
are not likely. If there is a "mexican version" of the story I would enjoy any enlightment.
Did not talk to the crew myself but I have information that the conversation between crew and duty manager was conducted in plain clear english.
As RatherBeFlying states the quote "do not follow TCAS commands"( in the approach sector to MEX) is original and as I understand varified by the BFU. :(
Thank you for your replies.


9th Jan 2003, 10:34
Could this not be a reference to switching from 'TA/RA' to 'TA only' in some busy terminal areas?

When I used to fly into Orlando Sanford on the 767 the brief for the airport was to switch to 'TA only' due to the intense light a/c traffic in the area, often on a parallel runway.

Similar reason why QRH for engine failure calls for 'TA only' on the TCAS, as an RA may lead to more problems than it solves when overloaded with targets.

Does anyone know the maximum number of resolutions current TCAS systems can resolve at anyone time?

9th Jan 2003, 13:59
According to my information the procedure you describe did not exist for MEX at the time the incident took place. Talk within the fleet is that the mentioned statement has been made exactly like quoted without turns or bends to allow misinterpretation.
But our friends from MEX who posted in PPRuNe before(buffalowing)? should be able to correct me.

For a better understanding of TCAS(ACAS) I recommend to read http://www.eurocontrol.int/acas/. Please click onto TRAINING PROGRAMME-ACAS TRAINING MATERIAL in the blue field left 5th field from top, than engage upper right first line yellow TRAINING BROCHURE VERSION 2 and you find 28 interesting pages. (Deals with TCAS II version7.0)

Danny, on page 14, they state that in Mode A/C and interrogation in Mode S TCAS can simultaneously track up to 30 aircraft in a nominal range of 14 NM for Mode A/C targets and 30 NM for Mode S targets. How many resolutions the system might process simultaneously? Good question? Will try to find out!;)

Best regards

Edit: traced it at http://www.honeywelltcas.com/general.htm.
System Honeywell CAS 81 6MCU can track as many as 45 AC, display up to 30 of them and can coordinate a resolution advisory for up to three intruders at once.
Hope that helps.

ATC Watcher
9th Jan 2003, 15:50
Capt 104 e-mail me directly ( via the private forum ) if you want.

Your ( edited) answer to Danny on multiple tracking encounters is correct.

9th Jan 2003, 21:25
O.K. I stand corrected, the statement seems NOT to have been translated in the German report. However I think we're still dealing with a language barrier since the Duty Supervisor most likely is not a native English speaker. Was the German who spoke to him a native English speaker?...

In any case...
Let my contribution to this thread be that: There is NO RULE in MEX that states: "Do not follow TCAS commands".

Whether someone said that or not.

the rooster
12th Jan 2003, 00:32
hi. the following taken from my mexicana operations manual, under TCAS procedures. (extract)
1 Use of TCAS is recomended and should be used in all fases of flight, except when conducting simultaneous approaches (not the case) ta only mode should be used.
2 Use standard fraseology, common to tcas operators to facilitate pilot controler communications, and avoid confusions.
3 as TCAS is in trial period in National airspace , after having an Ra, pilot and controler should file a report with a copy to the tcas commision.
4 in case of Ra, ATC rutinarily a) marks the tape, b) sends the tape and transcription to the DGAC, and a copy to the TCAS commision.
Another set of recomendations is given for operations in U S aispace. The main difference maybe is that while flying in the US once you initiate a manouver in response to an RA, the controller is no longer responsible for traffic, terrain or obstruction separation, until you return to your assigned altitude or inform the controller you are clear of conflict.
Perhaps this is what the atc duty supervisor was trying to convey to the LH crew, not very successfuly.
There is no mention anywhere, in the mexico city charts or any other place about "not following RA's in the mexico city area".
A routine investigation should be available fom the DGAC.
All mexicana pilots are familiar to RA´s, and trained to comply.
What we need to focus on, is the facts. what was both aircraft clearance? what was their rate of descent? was there a third aircraft? etc. etc.
obviously somebody messed up. But what makes this not just another RA? or rather what made this airlines come within 100 ft vertically?
Hope this information was useful.


12th Jan 2003, 11:56
Interesting post. Danny's speculation (use only TA Mode) would not be that far off than. I would like to refrain from further comments and plan to intensify my private "reseach".
If there are real news I will post them. Have a nice weekend.


ATC Watcher
23rd Jan 2003, 06:31
Got more info from Mexico now. It looks like testosterone played a major role in the way things escalated and were finally reported.
DLH 747 was nr one for APP but refused the APP ( due Wx) , MEX A320 was nr two and was asked if able, and he replied yes,, was given a heading and a descent. The A320 did not turn immediately but started descending with a very high rate. and this caused apparently a TA, then a RA to the 747 .
A Learjet was number 3 just above the 747 . When the 747 reported climbing due RA the controller replied "negative " because of the Learjet, but also because the A320 was already 2000 feet below the 747 by that time. .
According the mexican minimum horizontal distance between all 3 a/c was between 10 and 2,5 NM .
The conversations that followed were not really relaxed I understand. The reported words , said by the Mexico APP duty Supervisor : "in Mexico do not follow TCAS " as reported by the DLH Capt are definitively out of context and are part of a much longer conversation aiming to carry to the DLH pilot that in Mexico TCAS is not enforced ( i.e not mandatory ).

The Mexican regulations however allow the use of TCAS and spell out the conditions of its use and these are similar to those of the rest of the world ( based on the ICAO ACAS Doc)

What I personally find a bit disturbing in this affair, if that a rather respected Accident Investigation body, The German BFU, publish an interim report that is only based on a ( possibly exaggerated ) report of events by only one crew member. In the past they always were waiting a little longer to get the other side report, , and in this case , at least the radar recording video and the R/T transcripts of both frequencies.
When the Mexican DGAC will make its own report public, it could possibly all prove to be just a blown up mediatic storm in a small cup of Mexican tea.