Antonov Design Bureau's Oleg Korshunov Interview
"PLF101 Do You See the Ground?" - A Command that was never issued
PHOTO by Marek Borawski/Nasz Dziennik
Piotr Falkowski speaks with Oleg Korshunov, an experimental navigator with 38 years experience within Antonov Design Bureau.
Q: How did your interest in Smolensk crash come about?
Korshunov: - I have been interested in matters of flight safety for years. I have participated in different crash investigations numerous times; however, never as an official committee member. After death of Vladimir Tkachenko, who was a pilot with outstanding merit and a specialist in air incident investigations, I prepared further editions of his "Flight Risk" manual for publishing and I also wrote several chapters for this book. I constantly collect information on all air incidents, especially the more unusual ones. When it comes to Smolensk my attention was grabbed by the fact that the crash involved a government plane with head of state on board. From the air flight point of view everything seemed clear.
Chief air traffic controller stated that there were no suitable conditions for landing and ordered the plane to land at alternate aerodrome, however, the first pilot decided to make an attempt at landing. The pilot was allowed to lower his altitude to 100 meters, but on his own accord he decided to continue descent until he saw ground, which he failed to do - hence the plane crashed. The crew's fault was obvious, and the air traffic control group worked strictly according to the instructions. It issued correct instructions, so it couldn't be blamed for anything. This is how MAK (Interstate Aviation Committee) report presented it. I watched the famous press conference on 12th January 2011, where this verdict was announced. At that time I had no reasons at all to question it. I was very surprised that Polish side was objecting to things and making remarks. However; after I read MAK report later and I found things in it that infuriated me.
A dilettante operating the navigational radar
Q: What do you mean?
Korshunov: When the conversation transcript from the air control tower was made available, it became obvious that the air traffic control group was working in an appalling manner. It wasn't only during Tu-154 approach, but also earlier in the day, during Yak-40 and Il-76 landings. With regard to Il-76, this was also a near miss. But that was a Russian crew, who knew the airport, and had better weather conditions. Yet they decided against landing. There were four approaches to landing that day. Yak-40 landed really badly, Il-76 approached twice and didn't land, and weather kept getting worse. Then Tu-154 approached and flight controllers cleared it for landing? This is absurd. What kind of landing when there's practically nil visibility?
Q: What were the irregularities with Yak-40 and IL-76 landings?
Korshunov: As you are probably aware, we have a concept of weather minimums in aviation for a particular system of landing. The minimum vertical and horizontal visibility is established. If airport weather conditions are below the minimums, the clearance to land is not given. In this case it was 1000 meters of horizontal visibility and 100 meters of vertical visibility. Yak-40 approaches for landing, but the air traffic controllers know that they are supposed to receive three planes this day. The reactions to changing weather are very interesting. At 4.58 GMT, the chief air traffic controller announces through the radio: "Visibility 4 kilometres" Hardly 9 minutes pass and it's only 1500 meters. He received this information a moment earlier from the meteorologist on duty. Let's explain that meteorologist is mainly needed to provide air pressure reading, wind vectors or humidity levels.
Visibility is determined based on an orientation points' diagram and it's written down in the log. Flight control tower has its own diagram and chief air traffic controller can establish visibility at will without meteorologist being present. What he interprets has the same official value. The only difference being that the meteorologist writes the value down in the log and the chief controller doesn't. Let's go back to the Jak-40 landing. After another minute visibility goes down to only 1000 meters, so the weather is deteriorating rapidly. The crew in IL-76 can also hear the readings. Now it turns out that during 10 minutes horizontal visibility deteriorates fourfold and miraculously comes to a halt. No other value for this parameter is broadcast through radio until the landing of Tu-154.
Q: As if the weather deliberately adjusted itself to minimum conditions of the airport?
Korshunov: Exactly. I think this is it. Only the weather indicators haven't stopped at all. When Yak-40 approaches for landing, its position is visible on a radar screen. The chief of approach control tower provides the crew with distance to runway and gives a familiar expression: "En-route, on path" And so go four, three, two, one kilometres ... At this moment pilots should see the runway as allegedly the visibility is one kilometre exactly. In the meantime 13 seconds go by - this is nearly a kilometre of aircraft flight - and the flight chief shouts: "Can you see the runway?" After 6 seconds he orders the plane to execute "go-around". The actual landing takes place nearly half a minute later. As if he was flying that kilometre for 44 seconds.
That’s right. In reality, Yak-40 was not "on path" but much higher and practically touched down halfway through the runway and the weather was past the minimum requirement.
Q: This misjudged "on course, on path" will appear again during Tupolev's landing. Why did the chief of approach control tower misguide the crews? It is said that in fact he couldn't see anything on the screen, because there were trees between the radar and the plane.
Korshunov: It might be the case with Tu-154 because it descended really low, but it's not the case with other planes. Major Viktor Rhyzenko's behaviour remains a real mystery. I believe it's the result of the lack of professionalism, lack of responsibility, and negligence in performing his duties. Rhyzenko was receiving planes approaching at an angle of 3 degrees 10 minutes, when this airport's parameters are 2 degrees 40 minutes. It seems that he has never familiarised himself with the airport's manual. Rhyzenko's permanent placement was at Twer. He turned up in Smolensk few days earlier and this was in fact his first working day because on 7th April the weather was good and there was no need for radar. Therefore, this was his first time behind the desk.
In this case he should have familiarised himself with the airport's specifications and a trial landing should have been performed especially for him. Nothing like that has been done. This officer wasn't performing his duties at all. In the evaluation of Tu-154's landing, MAK states that although the plane wasn't on path, it was within permissible deviation parameter, that is half a degree above or below the path, and if the aircraft is within permissible deviation parameters, it means that no special actions are required. But this doesn't mean that one can mislead the crew.
According to MAK, when the plane is within permissible deviation parameters then the common practice is that the chief of approach control tower informs the crew that they are on path. That is not true. It's true that there are no reasons for concern and landing shouldn't be stopped, but the radar operator should inform the crew about it and give them the deviation value in meters, for example: "You are 40 meters above path" This allows pilot to take corrective measures. If according to MAK such a practice existed, then it wasn't in line with the official instructions.
Q: It is a sort of a problem since Russian military instructions are not accessible, no one knows what's written in them and Polish prosecution can't get hold of those documents in any way?
Korshunov: This poses a formal but not a real problem for investigators. Military personnel have their own, typical military instructions concerning specific fighter planes' operations, armament, etc, but a flight dispatchers or radar operators have exactly the same, uniform work technique. Have a look at this. Here we have official instructions to be used by the chief of approach control tower. Chapter 5, point 5.3 deals with descent in RSP + OSP system (radar and two beacons).
"In case of deviation of an aircraft from course or path the dispatcher instructs the crew to proceed to a given trajectory and reads them the value of the deviation." Please note that we are talking about the deviation from the path, not an area of permissible deviations. Further in the instructions we have a detailed description of how to pass on the information, that there need to be pauses in order to have a two-sided communication, etc. In any case, the dispatcher didn't do that. And MAK is trying to defend him.
"Something is worsening"
Q: We were talking about the landing of Yak-40. What about Il-76?
Korshunov: Exactly the same. All the time visibility is apparently one kilometre. And it's being repeated that the plane is supposed to be on route, on path, and one kilometre away, and nothing is happening. After some time has passed Lieutenant-Colonel Plusnin, the chief flight controller, asks the pilot, whether he can see the runway. Several more seconds pass by and the plane finally appears, but it's not possible for it to land because it transpires that the plane wasn't on route at all. He was too far left and too low, so he proceeded to go-around. IL-76's first attempt at landing ends in Plusnin and Colonel Krasnokutski not being able to come out with any other response but swearing.
Despite all that they still instruct the plane to proceed to a "go-around"? I would like to point out, that at no time there is even a mention of visibility conditions, which means one kilometre still stands. MAK reported later that it was all taking place during gradually deteriorating weather. And this happens to be true. If the visibility was deteriorating then it means that it was below a thousand meters, so legally not acceptable. This is why the flight control group is not mentioning anything through radio communication. Only Plusnin suggests the true situation to the crew by saying: "Something is worsening". However, he doesn't explain what is worsening. At IL’s second attempt the story repeats itself.
Q: What was the actual visibility then?
Korshunov: We know it very well. Colonel Krasnokutski, who was present at the flight control tower, was reporting the visibility to his General on the phone. The question is, whether he had the right to do so without being a member of the flight control group, and whether he had the right to be present in a place, which is a restricted access area, similar to the pilots' cockpit. Anyway, by being present there, he was obliged to maintain silence and not to interfere with the work carried out by the members of the flight control group. There is one benefit from his presence there.
Mainly, he recorded the actual visibility conditions during the landings of IL-76 and Tu-154, which were considerably different from the increased value broadcast by, as Plusnin put in his own words - a lunatic meteorologist. Report doesn't mention this fact anywhere, and it was vital information. He wasn't lying to his general. When Il-76 nearly crashed and finally took off, the colonel said: "Visibility is 500 meters, or 300 meters even. He then shouts obscenities at the meteorologist, who for some unknown reason was broadcasting the visibility at 800 meters. After half an hour Tu-154 was approaching and they had to transmit the weather conditions to the crew. Meteorologist is still transmitting 800 meters, but Krasnokutski can see from landmarks that it's "200 meters maximum " and loudly repeats it twice amidst the swearing and then also adds that it's 150 meters and still deteriorating.
Q: But when Tupolev attempted landing, the chief of flight control tower informed the crew that the visibility was 400 meters.
Korshunov: Yes, that was a broadcast value. Then, the flight commander stated that he would attempt a descent, and without proper conditions he would proceed to take off.
Q: Is this in line with the procedure?
Korshunov: By all means. Sometimes conditions improve during such a trial descent. However, you can only descend to the clearance altitude. Of course 400 meters is far below the minimum of 1000 meters, but landing with 150 meters visibility is an absolute nonsense. No one would agree to trial landing in such conditions. But he was told it was 400 meters. Krasnokutski tells the general it was 150 meters but there's no response. MAK also ignores that issue later.
Q: MAK states that they were acting in accordance with the procedures and they couldn't forbid the Polish plane to land.
Korshunov: This is nonsense. MAK calls on Russian AIP, which is a compilation of flight information (Eng. Aeronautical Information Publication). It refers to all flights within the Russian Federation air space, whether civilian, government, domestic, or international. It governs crews, and flight control staff, that is flight information ones and traffic control ones. Technical committee states, that the flight control staff warned the crew about the lack of suitable conditions for landing and that it recommended take off to destination alternate aerodrome. Now, AIP in its AD part states in Par. 1.1-1 c), that "first pilots of foreign aircrafts, who are flying across Russia, make their own decision about takeoff and landing possibilities, thus wholly assuming responsibility for their own decisions."
So MAK argues that the first pilot was informed of the conditions, yet he still decided to attempt landing. In this way MAK justifies the chief of approach control tower, because the pilot agreed to trial landing knowing that the visibility was below minimum. But further on in AIP there is a paragraph e), which is omitted by technical committee on purpose: "If necessary the flight control staff has the right to cancel any takeoff or landing, however; this right should not be treated as assuming responsibility for decision made by the first pilot or as a form of control of his pertinence." This means that if the chief of flight control cancelled all landings before the plane was on path, bearing in mind he had the right to do so due to weather conditions; and the crew ignored it, then it could be assumed that the actions of flight control were correct and could not be faulted. The commission only took paragraph c) into consideration, and failed to notice Paragraph "e").
But with existing conditions and an idiot behind the radar, who nearly crashed two planes earlier on, there is an utmost necessity to cancel any landings. It would have been the case even if no lies were told concerning the visibility, but during the manoeuvres before landing the conditions deteriorated. The only way to proceed was to cancel landing. AIP doesn't clarify what "necessity" can arise, because it's impossible to foresee all the diverse circumstances. It counts on the dispatcher's common sense.
Q: MAK can state that the dispatcher has the right, not duty to do so. And that is a difference.
Korshunov: First of all, law was created to be practised. Moreover, AIP has another entry. It states in ENR part of it, Paragraph 2.3.10 that: "It is the dispatcher's duty to cancel an aircraft's landing and to instruct it to proceed to go-around, when there are obstacles in the aircraft's descent or on the runway, which jeopardise the safety of the flight." It concerns all Russian, foreign, civilian, government and any other aircraft. The question is, what kind of obstacles (Russian priepiatstviya) could those be? Those aren't stated anywhere, because circumstances can vary significantly. It doesn't have to be a physical obstacle.
Manuals mention for example wind shear, which is a dangerous occurrence for an aircraft - in this instance a go-around is also advised. Could it also be fog? At an airport without a Precision Approach and Landing System, fog should be treated exactly in this manner.
Q: MAK accuses the crew of attempting to land without stating the preference for landing system. It says, that "the radar was not requested".
Korshunov: That's immaterial. If the crew doesn't inform of their expected navigational security system, then the chief of flight control tower indicates the system in operation. He should have said: "descent by radar, control with location beacons".
This is a type of instruction. The aircraft finished fourth turn, goes on the path and assumes a landing configuration but the chief of flight control can't give permission to land but expects to be able to give that permission soon. Then he says: "Posadka dopolnitielna", which means that the crew can continue descent but they have no permission to land. The final decision should be arrived at before the clearance altitude and no later than by the marker of the nearer beacon, which is about a kilometre away from the runway's threshold. This most often happens at busy aerodromes with heavy traffic, when an aeroplane has landed but hasn't cleared the runway. Then the next aeroplane can descend and at the right moment it will get permission to land or an instruction to proceed to go-around if the runway is still busy.
Q: But this wasn't the case in Smolensk, only bad weather.
Korshunov: Such a command can be also used because of the weather; for example when visibility is on the verge of minimum and improving. In this case, it would be at 900 meters and rising. Then you can count on the possibility that during those few minutes the visibility will reach thousand.
Misleading the crew
Q: This also isn't about us alone.
Korshunov: On the contrary. Flight control group did everything to mislead the crew of Tu-154, like it happened with prior flights. However; unlike Tu-154, Il-76 managed to escape. To be honest, even Il-76 was close to crash and it wasn't far off from having a different ending to the story. But he still managed to escape. Tupolev was also receiving a constant message "on path, on course".
Q: In case of Tu-154 the error involves not only the path and the course, but also the distance from the runway's threshold.
Korshunov: That's right. Scenario was the same with first two planes, which we established by analysing Yak-40. What we don't know is what the error was exactly. With Tu-154, we have very precise information on trajectory; for example, when Rhyzenko says: "2 on course, on path", he gives out 3 pieces of wrong information. The plane wasn't 2 kilometres from the runway's threshold but over 2.5 kilometres, it was 20 meters below path and about 50 meters to the left, so it also wasn’t on course. The error of 500 meters distance from the threshold is unexplainable and unacceptable. This is a distance a plane covers in 7 seconds. The distance should be precise. Error resulting from movement of the aircraft is 100 meters maximum. Despite all that MAK doesn't see any irregularities within the working pattern of the flight control group. It states the group's actions hadn't influenced the air accident. How can you write something like that?
Life shows us that the conclusions of the air incidents commissions are not always objective. It was a common practice in USSR that political and departmental interest would influence the course of investigation. I doubt whether there has been any substantial change to this situation since then. I have no illusion that in this case the commission had guidelines "not to blow the whistle on anyone and to keep everything under wraps", which came from the higher management of the Russian Federation. However, MAK and Mrs. Anodina had only one thing in mind - to defend the controllers in order to save "the honour of the Russian soldier's uniform", even if it was done in a clumsy manner.
Q: Isn't it odd that there weren't any better trained controllers available to guide a special aircraft with head of state on board, bearing in mind that three days earlier Russian Prime Minister landed there?
Korshunov: Criminal activities of the members of the flight control group are not an accident; it's a consequence of systematic failure in the army. The radio and telephone conversations which involve military personnel are a pointless jabber half the time, and often full of vulgarisms. It definitely isn't an accommodating environment for a reliable performance during flight control. People at the "Corsair" control tower didn't speak English, not even basic phrases used for radio communication with an aircraft, and they weren't following procedures. It was a group of dilettantes, who were able to perform their duties, after a fashion, in good weather conditions, when aircraft crew can approach landing without any help. It's enough to give standard commands, pressure, wind, and that's all - the plane lands. And now they are receiving a special flight from Poland, not any of their own aircrafts - a great responsibility, the generals are calling and expecting up-to-date reports. But it's fog everywhere. This fog caused confusion within members of the group, they lost their common sense in decision making and giving orders.
That's why official instructions were created - so that they can be used for guidance. Everyone in this profession has to bear in mind the phrase "All aviation regulations are written in blood". If you are the chief of air traffic control, then you have set instructions, mandatory duties which need to be completed. No one, not even a general, can interfere with that or order anything against the rules. This is the law - no one is allowed to give orders to chief air traffic controller whilst he is on duty, because he is responsible for safety. Everything that happened at the aerodrome on the morning of 10th of April 2010 brings a horror film to mind, with the members of the flight control group and the crew of the landing planes as the main protagonists. Flight control station was in chaos, which led to panic, there were endless consultations with the management staff on who was flying, where from and where to, and how to proceed in case the weather conditions deteriorate, and so on.
There was no consistent co-operation or performing of duties in line with the function performed. One might argue that the obsolete "half-functioning" equipment at the North Smolensk Aerodrome can be explained by the disarray and ubiquitous poverty in this post Soviet area, but the lack of professionalism and irresponsible actions of air traffic controllers, who achieved high military ranks, salaries and pensions, cannot be explained by anything.
Approach Cards without warnings
Q: How do you evaluate the actions of the Tu-154M crew? Their actions received an unimaginable scrutiny.
Korshunov: The crew were given vertical visibility of 400m and clearance altitude of 100 m. First pilot had his own minimum of 60 meters for vertical visibility and 800 meters of horizontal visibility, although this airport had higher values of 100 meters and 1200 meters respectively. So it's possible that he decided to descend to 60 meters instead of 100 meters. The clearance altitude indicator on the radio altimeter points towards that. This is an abuse of rules, but most likely he considered it a slight one. With respect to the horizontal visibility, he could expect the situation to change. Sudden appearing and disappearing are typical characteristics of radiation type fogs.
Anyway, he was definitely thinking that in any case he could proceed to go-around from 60 meters altitude without any problems. That's not an issue at all. So the plane kept descending. The navigator dictated altitude based on radio altimeter - I heard that in Poland it's a commonly accepted practice that at a certain altitude measurement instruments are switched from barometric altimeter to radio altimeter, which makes sense, because it increases precision.
Q: But, Flight Captain Protasiuk was aware that there is a land depression before the runway.
Korshunov: That was the navigator's job. Naturally, the crew prepared for flight as they read documentation, maps, and charts. For landing they received an approach card for North Smolensk Aerodrome in OSP+RSP system, with 259 degree course. When you look at that card, you can see all the potential navigational obstacles. All the land elevations and towers were marked but they are all positioned far from the runway. In a vertical cross-section chart there also is a straight line of the path and a straight line representing the ground. There are no warnings about the dangers. There are no dangers visible in the topography of the landscape. Although this card relates to the military aerodrome, it was prepared in the same way as AIP system prepares cards. In practice pilots rarely use those directly, they prefer prints that show the same information, but arranged in a more cohesive manner. Europe mainly uses aids published by Jeppesen. Lieutenant Artur Ziętek was probably used to those as well. The landscape topography similar to one in Smolensk is not unusual, there are many aerodromes like that around the world and pilots understand the danger related to taking altitude measurement in such situations. Let's look at Luxembourg aerodrome for example. It is very similar to Smolensk aerodrome in terms of landscape topography. Have a look at what information is included in Jeppesen’s guide about it.
Q: "Rapid drop of radio altitude between 0.8 and 0.5 Nautical Mile from the threshold of runway due to steeply rising terrain (300 feet). Anticipating ground proximity warning."
Korshunov: Exactly. This is printed in a box on the approach card, so that everyone can clearly see, that radio altimeter reading in this area will be wrong. It is clearly stated that there is something like that in the topography of the landscape and radio altimeter shouldn't be used and that warnings about proximity to ground can be triggered, exactly like it happened during approach in Smolensk. They considered it important information, and they were right to do so. Russian documentation has no such information included. They decided it was immaterial. They could have included following in the box: "Depression of terrain to 80 meters at a 0.5-2.0km distance from the threshold of runway 26. Do not use radio altimeter". That's logical. This is why the young navigator, who was probably used to flying with Jeppesen's catalogue, knew that if there are issues with landscape topography then it would be mentioned in the diagram. When there's nothing written down, then there are no problems, landscape is flat and radio altimeter can be used without fail. I presume this is why he ignored the pressure altimeter.
Q: What happened later?
Korshunov: The chief of the approach control constantly repeats: "On course, on path" and he gives the distance. The aircraft is 2.5km away from the runway and far below the approach path, and even beyond the acceptable deviations when the chief of approach control says: "2, on course on path". But the crew aren't aware of this. They are calm, believing the descent is normal, everything goes in flying colours, and the pilots have already started looking for ground. They couldn't expect to see anything at horizontal level but at vertical level there was a chance to see ground. What's more, the first pilot increases his descent speed assuming he has some spare altitude left. He could have thought that if he descended a bit further he would come out below the clouds and see the ground. But then Rhyzenko went quiet, despite his duty being to bring the plane to one kilometre distance from the runway's threshold. This man lied to the crew at 2 kilometre distance and went quiet. The chief of flight control is also quiet, regardless of the fact that he knew the plane was within clearance altitude. He should have asked: "Can you see the ground"? He would, of course, get a response: "No". Then he would have to give them an instruction to proceed to "go-around".
Deafening silence at the tower
Q: "Corsair" tower remains silent for a number of seconds, and that means a kilometre worth of flight distance.
Korshunov: At the end, when the plane is far below the path, Rhyzenko can't see it on the radar any more due to the topography of landscape and trees. But this is no reason to remain silent, but a reason to instruct them to depart. Finally an instruction: "Horizon". The whole point being that there is no such instruction. The correct instruction should be: "Stop descent" (priekratitie snizheniye in Russian). "Horizon", or in other words "horizontal level" is an instruction taken from a standard military radio correspondence. It refers to changing into a horizontal flight. But it doesn't have to be obvious to a foreigner. I completely cannot comprehend Rhyzenko's behaviour.
Q: During this time the aircraft is descending fast.
Korshunov: Navigator is constantly giving altitude readings, but because the aircraft is flying above the depressed terrain, the radio altitude remains constant at 100 meters. During 7 seconds navigator repeats three times: "100", as per his radio altimeter indication. Question is, how did the first pilot understand it? He knew the plane was constantly descending, because there also is a vertical speed indicator. When he heard the repeated "100", he could have interpreted it as a reminder of the parameters for clearance altitude. Then the first pilot has a duty to clearly state: "Landing", or: "Departing". The navigator could have asked outright: "First pilot, decision please?" This is how I would imagine Captain Protasiuk thought. He didn't react, because he decided to descend to 60 meters, so he prolonged descent. On the other hand, the navigator should have noticed that it was impossible. The plane is moving downwards and altitude remains constant? Maybe he was thinking they changed to level flight and were departing?
Q: Then a command "We are Departing" is issued
Korshunov: You have to give it to the first pilot that he didn't wait till 60 meters; he realised something was wrong and he attempted a takeoff. The graphs clearly show a strong pressure on the rudders. But the take off manoeuvre was unexplainably prolonged; unfortunately, until it was too late.
Thank you for the interview.
Source: Nasz Dziennik, "PLF101 czy widzisz ziemie?" April 10, 2014
Translated by Anna Zatorska-Batt