A Word on the Latest Nigeria Air Mishap – By Dr. Philip A. IkomiArticles, Columnists, NNP Columnists, Philip Ikomi Thursday, June 7th, 2012
I would like to first of all send my heart-felt condolences to all whose loved ones lost their lives in both the air cargo accident in Ghana and the Dana flight in the suburbs of Lagos.
On Saturday, June 2, 2012 a Nigerian registered cargo plane operated by Allied Air ploughed through the airport perimeter into the highway outside the Kotoka International Airport Accra, Ghana. This plane had landed and somehow was unable to stop within the confines of the runway and so ended on the highway where it collided with a passenger carrying bus with the collision resulting in the untimely death of ten people according to news reports. What do we make of this? There are several plausible reasons the plane could not stop. The primary one is that the runway was wet and slippery and as a result there was inadequate friction between the tyres of the plane and the runway asphalt which would ordinarily permit it to stop within the tabulated landing distance taking the prevailing weight, density altitude or runway elevation and atmospheric temperature into consideration. However, before you even consider the frictional forces, you have to have the plane touch down at a specific distance within the runway because if the plane touched down further down the runway than the performance charts assumed for the determination of its stopping distance, it obviously will not stop at the end of the runway’s stopping distance available. Touching down within the first four hundred and sixty meters (fifteen hundred feet) of the runway threshold is generally the spot recommended for a jet aircraft to target in order to stop within the performance limiting stopping distance of such an aircraft.
Thus the investigators will be checking through observation of the skid marks whether or not the plane touched down within the first four hundred and sixty meters (fifteen hundred feet) of the threshold of the runway. To be able to touch down on this spot, the airplane has to be flown down a three degree or a little higher glide path to the runway depending on the noise level permitted over the terrain below the glide path. If the terrain below the glide path does not permit a lot of noise, the glide path has to be higher than a three-degree slope. Now, every aircraft has an optimal approach speed in the landing configuration which depends on the weight of the airplane and which the pilot must diligently fly to the runway threshold before commencing the reduction of speed to flare out and touch down. If a pilot allows this speed to get out of hand and the airplane is either too slow or too fast, then the plane would not likely make the targeted touchdown spot. If the plane was slower, it could stall and fall short; however, if faster, it may overshoot the spot and require a longer stopping distance which the runway may not have.
So far, I have not talked about the nature of the plane in terms of whether or not it is a new or old plane. Normally no aviation personnel talks about old or new planes because aviators do not see a difference between the new and the old. We see planes through their performance and serviceability to fly. For commercial jet airplanes there are components that enable the pilot to effect changes in the tabulated landing distance of the plane. One of these components is the thrust reversers to reverse the forward thrust enabling the airplane to slow down considerably more than using brakes alone to stop the plane after landing. In addition to these are the ground spoilers which “spoil” the airflow over the wings when deployed on the ground after landing so that the plane does not move as smoothly through the air when on ground thus augmenting the retardation necessary to stop the plane. For various reasons, these two components are at times faulty and become inoperable when they are most needed.
At times, the thrust reversers are not working and at other times, it’s the spoilers that are deactivated. When you have good brakes and the runway is not wet, you could land without using the spoilers and if you have a long runway and the plane is not heavy, you may do without using the thrust reversers. When there is precipitation on the runway and the plane is fully laden, you need every device you have to enable you stop within the recommended distance or your plane could plough through the airport’s perimeter fence. In effect, the cargo plane disaster could have occurred for a number of reasons and only a thorough investigation can identify the cause or causes. The possible though not exhaustive causes are: Speed during the approach—higher speed than the recommended approach speed at touch down could lead to inability to stop and the blowing of tyres caused by the excessive use of brakes to force the plane to stop after landing. Higher touch down speed could also result in the tyres not establishing contact with the runway and thereby sliding along, a phenomenon known as hydroplaning or aquaplaning. When a plane hydroplanes, the brakes are ineffective, but the reversers and spoilers are effective. However, if the latter two are unserviceable, then the plane may not stop. Thus component failures—reversers and spoilers and even brake failures could have led to this result. Finally touching down further down the runway could also have resulted in this disaster.
The Dana flight is the other crash by a Nigerian registered plane that happened in Lagos state the next day (June 3, 2012) after the cargo plane crashed in Ghana. This flight has been extensively written about in the news media. This is understandable because of the huge loss of lives. Many of us were touched by this and I share their grief for the loss of dear ones. The most significant claim is that the plane had “hydraulic” problems and that the management did nothing about this only continuing the plane in service. (see Oyetunji Abioye’s story in Punch of June 5, 2012: http://odili.net/news/source/2012/jun/5/838.html ) (In addition, see Hugo Odiogor and Lawani Mikairu’s Vanguard on line of June 5, 2012: http://odili.net/news/source/2012/jun/5/332.html
However Dana officials denied this claim saying the plane was flight tested to Ibadan on Saturday June 2, 2012 and flew several trips already on Sunday June 3, 2012 without any incident before the final fatal flight which was the fourth flight that day. This report was in Punch on-line of June 5, 2012 where reporter Oyetunde Abioye further reported that the Dana Air Director of Flight operations said that the plane went from Lagos to Abuja, returned to Lagos and was on its way back from Abuja, which was its fourth trip between Lagos and Abuja before it crashed around 4pm. The Director said:
“The plane, 5N-RAM, left Lagos for Abuja at 7:47am on flight number 999. It later came back to Lagos on flight 998. It left back for Abuja again on flight number 993. It was on its way back to Lagos on flight 992 when it crashed.”
It is possible that the plane came down as a result of an engine trouble. In fact, it’s been reported that Oscar Wason of Dana Air told CNN that the American captain of the flight had reported engine trouble to the control tower shortly before the crash. I have read reports too about possible fire being the cause of the disaster. However one has to carefully examine all available reports to see where the evidence leads. Eye witness accounts may not be accurate taken as the only evidence but one can make inferences from eye witness accounts when they are the only sources one has. For instance, while the twin towers of the World Trade Center were crumbling reporters on the scene were reporting that they were hearing deafening explosions. People who came out of the buildings were also reporting explosions from the basement of the buildings where no airplanes struck. The whole buildings were pulverized and yet the 911 Commission report said that there were no explosions and the buildings came down due to fire burning through. I have read in the newspapers on line that some eye witnesses of the Dana crash said that they saw the plane moving in an uncontrollable fashion in the air, coming lower and lower and at a point started climbing up, only to come down again and crash into the building. Some others reported that they saw the plane hit a building burst into flames and exploded. Some others have reported that they saw the engine on fire. From all these one could infer that perhaps the plane started losing altitude as a result of an engine failure because it was reported above that the plane was losing altitude.
As a former airline captain involved in training other pilots and examining them to issue them with their type rating so they could fly a particular type of jet plane, and as a former instrument rating examiner, I can infer from the eyewitness report that said that the plane was moving in an uncontrollable fashion that they probably had an engine failure. This inference is based on my knowledge of the flying characteristics of a plane after the simulated /or actual loss of an engine in a two-engine plane. I have practiced simulated engine out procedures several times over with my colleagues who wanted to do their type ratings or who were renewing their base checks and I have had to demonstrate my own competence several times over my life as a pilot. So, I know from the eyewitness that the plane was losing height or altitude and it was moving uncontrollably. I also know from eye witness reports that the plane managed to climb a bit during this period before it hit the building. What does the slight climb tell me? It tells me that the airplane had a functioning engine, that is, it did not lose both engines due to engine failure. In other words it had an engine which was still running and in fact, you could also infer that it was because of the running engine that the path was zig zag. If it did not have an asymmetrical distribution of thrust at the initial stages when it was losing altitude it would have come down in a straight path. Now what are the expectations?
A twin engine airplane, like the Dana Air plane that crashed does not have to crash simply because of a loss of an engine eleven miles to the runway as reported. It was reported that it was about eleven miles to the airport by some papers. In case of an engine failure, the pilot flying puts all required effort to ensure the plane continues to fly in a straight path, not a ziz zag path or uncontrollably as reported by the eye witness. If the plane is not stabilized in a straight path, the forces acting on it would result in its losing altitude excessively. The next thing the pilot has to do after stabilizing the flight path is to ensure that the dead engine is cleaned up. This is usually done by shutting the failed engine by closing the throttles and fuel valves and if it was a fire that caused the engine malfunction, you fire the extinguishers on the failed engine. I would not want to believe that both engines failed here. In fact as I said earlier, the plane was flying in other than a straight path, indicating that the pilots somehow did not stabilize the flight path and the airplane engines were delivering asymmetrical thrust to the engines. Now, the plane is not stabilized and worse, the second engine which was functioning was inadvertently shut down! This I infer from the fact that the plane was reported to climb a bit before descending again. This means that the wrong engine was probably shut down in the ensuing panic from the failure of the first engine. Now the airplane cannot possibly fly again but headed downwards. It is not an unheard of event for a pilot to shut down a functioning engine when one engine has failed. I have had pilots doing their recurrent tests do this during simulated engine failures. One real life instance was in January 8, 1989 in a British Midlands airplane, a Boeing 737-400 where the pilot mistakenly shut down the right functioning engine when it was the left that was malfunctioning (see http://en.wikipedia.org/wiki/Kegworth_air_disaster#Causes
A thorough investigation will pinpoint the cause of the accident. If one engine failed and the other was shut down inadvertently the records in the engine data recorder will show it. If both engines failed simultaneously, which is possible but highly unlikely, that will also be known from the data recorder or black box. In fact, the entire last thirty minutes of the flight until the crash which would include the performance of the airplane parameters, like the speed, the position of the engine actuators and its indicators, the flaps, landing gear, outside air temperature and forces acting on the plane,( eg,g-loads) and others will be recorded. So next time you hear of an accident you don’t think of old or new airplanes, but the performance of the crew because in most accidents, pilot error is a huge concern. Engines are made extremely reliable these days and the human element is still the weakest link. For that reason, manufacturers have looked into automating a lot of elements in the cockpit. This automation was again called into question because of the interaction between the human pilot and the components of the automated system. I looked into this several years ago to determine if cockpit automation led to more accidents compared to mechanical failures or other causes and found that automation resulted in far less accidents than mechanical or other causes . My findings were published in a chapter in E. Salas (Ed.),
Advances in Human Performance and Cognitive Engineering Research ,VOL. 2. Boston, MA: Elsevier Science.
I have flown extensively in the Nigerian airspace and I have had my share of an accident although no life was lost nor did anybody sustain injury. However, the airplane was destroyed as I careened off the runway into the side strip. The problem was a poorly maintained airplane that should not have been flying. It was my first flight on the plane and I had only just joined the airline so I was not familiar with the plane to know that it had a tendency to veer off the runway which all other pilots knew about. Thus I was not ready for what took me by surprise but as someone who was quite conscientious in my calling I managed to control the airplane avoiding a calamity. To this day, I have not seen a report of that accident. I want to use this medium to call on the NCAA to publish all accident reports as the NTSB (National Transportation Safety Board) of the US does so that pilots can learn from their mistakes. It is no use saying that accidents will be thoroughly investigated only to confine the findings to the vaults of the NCAA with no members of the pubic having access to them. The data I used for my automation research covering a period of sixteen years from 1983 to 1999 came from the NTSB data base on the World Wide Web (WWW). The NCAA of Nigeria should publish their accident reports as soon as they occur the same way the NTSB does, on the WWW. The NTSB publishes an initial report which is usually a sketch of what happened and a more detailed report is published when all facts are in after a thorough investigation. There is no reason Nigeria should not do the same. We even have a greater need to show our people the reasons we have so many accidents so that they can be better prepared to avoid them.
Philip A. Ikomi, Ph.D.
Retired Airline Pilot and Psychology Professor
Philip A. Ikomi is an Industrial/Organizational Psychologist
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