Forgive me if I sound a little heavy on this subject, but after watching ‘Crowded Skies’ on BBC2 last night, I can’t stop thinking about the way the authorities are dealing with the air traffic controller on duty that evening, Peter X.
I refer of course to the DHL 757/Russian T154 collision over Lake Constance last year in which 70+ people were killed, the vast majority of which were children on a school trip. Until last night, my only concern was for the families of those victims and a wish that nothing like this ever happen again. Now, though I not only think this, but also feel terrible grief for the ATC on duty, Peter X.
The programme concluded that Peter X did infact make one or two errors that fateful evening. However, those errors, as is often the case, were only two in a series of errors and misunderstandings, most of which were out of Peter’s control.
My concern this morning is that this guy is now in hiding with the prospect of manslaughter charges hanging over him. I’m sorry, but I just don’t think this is right.
Lets put some approximate statistics on this. Lets assume the average ATC watches 10 planes every half hour, each plane carrying 150 passengers. If the ATC works for 8 hours in a shift, he would oversee 1,500 lives every half hour; thats 24,000 lives per day. If he works, say 250 days a year, that is 6 million lives he looks after. Peter X had worked for 8 years before this incident, meaning he had successfully navigated 48 million people safely over this period.
Of course these numbers are approximations, but does this sound like a man who deserves to be punished?
We all make mistakes, we are all human and Peter X will have to live with this error for the rest of his life. Surely, manslaughter and jail is one step too far?
I liken it to stepping in a car and taking a drive. How many times do we, as drivers, take our eyes off the road for a split second for any number of reasons? Once a week, once a day, or several times a day? If someone walked out in front of us during that split second, we too could end up in prison for dangerous driving. We all aren’t bad people, we all aren’t criminals but we all everyday do things which aren’t pre-meditated, which ‘could’ if luck and fate were against us, could result in the death of someone else.
Its my belief that thats all that happened here. Luck, fate, and a series of things happened which caused this crash and one man looks like he may get blamed for it.
I just feel so sorry for this guy and am quite angry at the ‘blame’ culture that is starting to affect the airline, and other industries globally at the moment.
What does everyone else think?
By: GZYL - 21st August 2003 at 18:42
Thanks Wys! So lateral TCAS will come then?
By: wysiwyg - 21st August 2003 at 12:32
GZYL – As above, TCAS lateral separation is still yet to come. There are 3 stages to a TCAS ‘event’.
Under normal circumstances traffic in the vicinity will show on the screen as a white hollow diamond. The diamond will be supplied with additional information showing whether the other aircraft is above or below you (within 2700 feet) and whether it is climbing or descending.
The first stage of a potential conflict is for the white diamond to become filled in. This has no aural message accompanying it but the other traffic is then referred to as being ‘proximate’.
If the proximate traffic gets within 50 seconds of a collision the diamond will turn amber and a warning aural would sound saying ‘TRAFFIC, TRAFFIC’. We call this situation a TA or Traffic Advisory and if visual we would leave the automatics engaged but start looking for the other traffic. If not visual we would continue monitoring the situation on TCAS.
If the other aircraft gets within 30 seconds we now have an urgent situation called an RA or resolution Advisory requiring manually flown avoiding action in accordance with the TCAS instructions overiding ATC. The screen display shows the RA traffic as a red diamond and the aural is relevant to the required flight path, eg ‘CLIMB, CLIMB’, etc. At present all avoidance is in the vertical plane and I believe the system can cope with something like 8+ aircraft converging at once. Theoretically only one aircraft needs to take avoiding action to avoid a conflict. The system talks to the other aircraft involved to ensure that the guidance for all involved aircraft takes them in opposite directions. What you don’t need is to have someone (as in this case) deliberately go the other way!
Regards
wys
By: GZYL - 20th August 2003 at 19:30
Just had another idea! Can TCAS tell the aircraft to turn aswell? If so… couldn’t TCAS tell an aircraft to climb and or dive… whilst turning? That’s gotta get them out of the way of each other… and if you have conflicts between ATC and TCAS… it will still take the aircraft which obeys TCAS out of the way! Problem is, you could stray into another aircrafts flight path, causing new evasions, but you could suffer from that problem with the vertical separation too.
Perhaps Wys can clear up the problems with my theory!
By: wysiwyg - 18th August 2003 at 23:09
Yes you always follow a TCAS instruction first. The senior chap in the Tu154 right seat was totally for the failure of TCAS to resolve the situation. It was anothr example of a cultural issue at play in an aircraft accident which could perhaps have been given a bit more consideration in the summing up. In years to come TCAS will probably provide lateral separation in addition to the current vertical only separation which will give further sfaety benefits which would probably have saved these two aircraft despite the Russian mistake.
I too felt that Peter X was being set up to carry the entire can. His main sin was that he didn’t recall his help when the workload increased. The operational problems were more the fault of his managers and the confused state of operational affairs they had been allowed to employ.
Just as an extra talking point, did you know that almost all UK airlines have 10 days to fix a broken TCAS system, Therefore an airliner can be operated for up to 10 days with no TCAS! Now in theory the other aircraft is capable of responding and completing all avoiding action…so long as it hasn’t got failed TCAS as well!
By: dan330 - 18th August 2003 at 21:53
Seems like TCAS is a properly working system, just in this case you have one crew following the TCAS and the other following ATC, a recipe for disaster!
Is there a general rule around the world that says that pilots must use the TCAS over any ATC command in these situations? If so then it seems the “senior” pilot in the TU-154 played a major part in this, a lot more than Peter X in my opinion and that TCAS does work if it is followed correctly.
If not then it should be made clear to every pilot in the world that you follow either TCAS or ATC, so we don’t get the kind of confusion of one following one and the other following the other that caused this accident.
By: Dazza - 18th August 2003 at 21:26
I think the reason for the 757’s TCAS telling the pilot to steepen his dive instead of instructing him to climb is because to initiate a climb when the aircraft is already diving would simply take to long to have an effect on the aircrafts flightpath in relation to the impending collision, to increase the dive the pilot only needs to push the yoke further forward, to climb the aircraft would have to first pull out of the dive, I’m sure wysiwyg has the definitive answer.
Regards, Dazza.
By: GZYL - 18th August 2003 at 20:19
It just struck me on the programme where the 757’s TCAS told the pilot to dive steeper instead of climb to avoid disaster.
By: batbay - 18th August 2003 at 19:57
Surely, I would think, TCAS has a programmed decision maker dependant on the course being flown by each aircraft? Otherwise, it would be a system relying on which aircrafts TCAS was the first to react (eg I’ll climb, you descend).
Perhaps we can get the answer from one who knows?
By: T5 - 18th August 2003 at 19:20
Originally posted by GZYL
Could we improve TCAS so that it realized what the other aircraft was doing, and then modified the advice it gave?For example, TCAS told the 154 to climb, and the 757 to descend. When the 154 descended and a collision was still going to occur could the TCAS tell the 757 to climb and the 154 to descend? Or would the changes be too confusing? I.e. the pilots then follow TCAS orders… only 1 follows the first instruction, and the second follows the changed instruction! Getting confused already??? I am!!
What do the aviation authorities say about procedures to avoid mid airs? Should you follow the ATC? Or TCAS??
I get what you mean and think that if TCAS on the 2 aircraft on the collision course could communicate, it would be better and safer. One pilot is told to descend, so the other is told to ascend.
By: Moondance - 18th August 2003 at 18:54
Follow TCAS – last line of defence!
By: GZYL - 18th August 2003 at 18:44
Could we improve TCAS so that it realized what the other aircraft was doing, and then modified the advice it gave?
For example, TCAS told the 154 to climb, and the 757 to descend. When the 154 descended and a collision was still going to occur could the TCAS tell the 757 to climb and the 154 to descend? Or would the changes be too confusing? I.e. the pilots then follow TCAS orders… only 1 follows the first instruction, and the second follows the changed instruction! Getting confused already??? I am!!
What do the aviation authorities say about procedures to avoid mid airs? Should you follow the ATC? Or TCAS??
By: Moondance - 18th August 2003 at 12:59
In my view, TCAS is the greatest single advance in flight safety in my 20 years flying – the TCAS display featured on the reconstruction last night (B747 classic sim appeared to be standing in for the DHL B757), where traffic information appears on a VSI (Vertical Speed Indicator), is actually the least impressive presentation (a retrofit on an older aircraft).
Most modern aircraft (757/763 for example) present traffic within range (about 80 miles horizontally and +/- 2700ft vertically) on the EHSI map display, which makes it a beautifully clear presentation – TCAS escape manoeuvres are displayed on the EADI (Electronic Attitude Director Indicator), and again are very clear and easy to interpret.
The point about TCAS is that is purely an airborne device – the TCAS computers in the aircraft will communicate with each other to co-ordinate the escape manoeuvre, and it is up to the pilot to trust that totally. There is no communication from the TCAS computers to ATC, and when an aircraft is carrying out a TCAS climb/descent, ATC have effectively relinquished control. So the tragedy of the collision is that the Russians were obeying an ATC instruction, rather than following the TCAS commands.
As the programme showed, accidents are rarely due to a single event, but usually a chain of circumstances – sadly, I suspect Peter X will be presented as the scapegoat (far easier to blame a single human than admit a corporate failure)
By: T5 - 18th August 2003 at 11:54
I agree entirely and I said last night that I felt sorrow for the air traffic controller concerned.
I think this controller was only very slightly to blame and that there are more people out there who are responsible in some way or another.
Peter X had tried to put off technical work which was taking place, supposedly during a quiet period. This work was going to result in the system temporarily being down-graded to an older version, one that wouldn’t alert the controller of two aircraft flying towards each other. So for a start, whoever decided that the change of software was necessary should take some of the blame.
The technicians who carried out the work obviously didn’t carry it out as they should – the phone line was not working properly and when the air traffic controller spotted that something was wrong, he could not really do anything i.e. pass of the A320 Greek (?) flight which was on it’s way to Germany (?).
The A320 flight played a crucial role in this disaster. It distracted the controller from what he was supposed to be doing. As he wasn’t able to use the telephone to pass the flight onto someone else, he was really in trouble. As he tried to sort the late A320, the Russian 154 and the DHL 757 moved closer and closer together.
Next comes this TCAS system which is supposedly an avoidance system. Why do ATC (on the ground) and TCAS (in the air) not say the same thing? One of the aircraft received an alert telling it to climb or descend, but air traffic control was saying the opposite. Confusion amongst the crew of the crowded Russian cockpit, led them to do the wrong thing, descending. Straight ahead, the DHL aircraft descended, too. The air traffic controller believed that all was fine again and could finally get back to work with the A320. It was obviously at this point that the 757 sliced through the 154, killing dozens of people, 45 being children under the age of 15.
If I was Peter X, I’d be feeling extremely guilty, having been responsible for the two aircraft which collided with each other. On the other hand, I’d know I’d done the right thing. I would convince myself that I had done everything within my power, considering the circumstances – no telephone, no collegaues around and a control system which lacks its usual features.
What really irritates me about this and with other air crashes is when they say the crash is a result of “pilot error”. In this case, it is controller error. Let’s assume you are flying a plane which is perhaps doomed. All the engines have for some reason or another, failed, you’ve got hundreds of passengers out the back and you’re miles from anywhere. What do you do? You would do what you have been trained to, do what you think is best, trying to save as many lives as possibly upon impact. So for doing what any pilot is likely to do when a problem arises, you get the blame.
Much like this controller, what could he have done? He was powerless. It is likely that any controller would have acted exactly the same way as he did.
Before the technical work began, Peter X did telephone to request that the work be scheduled for some other time. This request was declined. So, whoever made the decision not to re-schedule the work plays some responsibility. By agreeing with Peter X and having the work carried out at another date, this crash would never have happened.
So many people could be blamed, but I do not think the controller who was supposed to be in control, is to blame.
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August 18, 2003 at 10:25 am