Exactly a decade ago, on November 1, 2011, LOT’s Boeing B767 crash landed at the airport without an extended landing gear. Chopin in Warsaw’s Okęcie. The difficult and dangerous maneuver was performed exemplary by the crew, and then the evacuation was carried out equally efficiently. As a result, none of the 231 people on board got hurt, and the event became famous all over the world.
As it was quickly established, as a rule, the emergency landing gear extension system worked. Only it had no power supply, because the C829 circuit breaker was turned off in the cockpit for some unknown reason. When it was pressed down, the landing gear of the plane lifted from the runway easily extended.
A careful examination accident it took the experts almost six consecutive years to make their recommendations. The comprehensive report of the State Commission for Aircraft Accident Investigation in 2017 describes exactly what happened. Although there are no definitive answers or indications of blame.
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All through the hose and fuse
LOT’s B767 took off from Newark airport near New York before the dawn of Polish time. Pre-flight inspections of the plane by the American technician, Captain Wrona and co-pilot Jerzy Szwarc, showed nothing abnormal. It was only in the air that the sensors detected a pressure drop in one of the hydraulic systems responsible for the landing gear extension. After deliberating with the ground, the crew decided to fly to Warsaw and extend the landing gear in emergency mode. Regardless of an apparently damaged hydraulic system. Seven hours later over Poland, to the crew’s consternation, this emergency system did not work. Consulting the ground, resetting systems, and verifying the positions of selected switches and fuses did not help. Attempts to force the landing gear to extend by means of gravity and sudden movements of the plane also failed.
By examining the plane, specialists quickly, even before it was taken from the landing site, found the root cause of the whole situation. One of the hoses in the hydraulic system has broken. As stated, it was partly the fault of LOT. As early as in 2000, the Boeing concern stated that the installation of this version of the conduit, which was put into production in 1995, was faulty. It was subjected to greater loads than it should, and sometimes it broke. So, a modification of the hose connections and a new method of its installation were developed. A set of relevant parts and instructions for the conversion are included in the so-called technical bulletin, about which all machine users are informed. However, it was given a low priority, so making the modifications was optional. LOT decided not to conduct it, relying on “its own assessment and previous experience”. According to the standards, the cable was checked every three thousand hours in the air. The last time technicians examined it was in March 2011 and found no problems. Eight months later, it cracked where Boeing believed it was most likely.
Regardless of this, the landing gear of the airplane should be able to slide out using the emergency electric drive. Therefore, the possibility of wire breakage did not raise an alarm. There was always a stock, the chances were small so the modification was optional. In this unfortunate flight, however, the emergency system did not work either. He had no right, because his power was simply cut off by the C829 circuit breaker turned off. Why didn’t the crew notice it? The Commission was unable to state unequivocally.
Key oversight
The C829 circuit breaker is located in the lower left corner of the P6-1 panel. So it was just above the floor behind the first officer’s seat, which was checking the position of fuses and switches at critical moments. The captain, sitting in his left seat, could not see him. The co-pilot, sitting on his own, could, but would have to make a great effort and had little chance of it. However, during the flight, he got up from his seat and walked around the cockpit. He even looked at the P6-1 panel, where the C4248 circuit breaker was also located, directly controlling the power supply to the emergency landing gear extension system. This one, however, is placed at its top, about 30 centimeters above the floor. He was pressed. For some reason, the pilot did not notice the C829, which was turned off a little lower, which was a collective fuse, the second layer of protection, among other things, for emergency landing gear extension and a few others, only working in rare emergency situations. The electrical systems and electronics of the aircraft were constructed in such a way that this fact was not signaled anywhere. There was also no mention of him in the emergency procedures.
In its analysis, the Commission concluded that such an oversight was possible due to the difficult and stressful situation of the co-pilot. He had been flying for hours, knowing that the main landing gear extension system had malfunctioned. The critical phase of flight, landing, was approaching. Additionally, for reasons which he did not understand, the emergency landing gear extension system did not work. All the emergency instructions on board did not help to solve the problem. At the same time, he had to communicate with air traffic control, the pilots of two F-16 fighters accompanying the B767 in the last hour of the flight, and above all, consult technical experts on the ground and follow their instructions. Everything under great pressure and on its own as the captain was focused almost exclusively on piloting. In such a situation, according to experts, it was possible that he had missed the fact of switching off the fuse, the importance of which was not communicated to him by emergency procedures or specialists on the ground. Simply checking the P6-1 panel, he focused on the key C4248 fuse and did not glance down.
The accident investigation experts emphasized that in modern aviation, the learned routine and automatic actions of the crew and strict adherence to procedures are of great importance. Only in the third place is independent analysis and critical thinking, for which in an emergency and stressful situation there may not be time and place.
The Commission also tried to explain why C829 was actually turned off and when it might have happened. Unfortunately, there was no clear answer here either. The fuse was examined in a number of ways and even shipped to USA. All tests confirmed no problems and correct operation. So the explanation remained that it was accidentally turned off by someone in the cockpit. The crew testified that they checked the position of all fuses before take-off, which they confirmed by signing a relevant document. So on the ground in the USA C829 had to be pressed, because no one noticed that it was not. It had to be turned off somehow later, after the pre-departure check. When and why remains unexplained.
But experts have found that airlines have reported problems to Boeing with the P6 panel in the past. Since it is located just above the floor and behind the co-pilot’s seat, fuses have been accidentally pulled out. Whether it is during cleaning, whether it is accidentally with the foot, or due to the crew’s bags containing documents. Boeing noticed the problem and first offered additional paid covers for the entire panel. It then introduced them as standard equipment, but not until a few years after LOT’s particular B767 was produced. The Polish airline did not decide to buy additional cover.
Accident without sequelae
Experts from SCAAI do not judge. They don’t pronounce guilt. They are not accusing anyone. They only state facts and make recommendations. In this case, they only recommended some changes to the instructions for pilots in case of problems with the landing gear and adding one in case of landing without it. Boeing rejected Polish suggestions. The Americans stated that the instructions should not be additionally complicated, they should be as simple as possible and assume that the crew will first verify the position of all the relevant fuses:
The checklist instructions advise that prior to the commencement of NNC checklists, the controls of each system are assumed to be in the normal configuration for the phase of flight. For the event under consideration, normal configuration means that the relevant fuses are in the correct positions (closed)
Similar recommendations regarding procedures were addressed to LOT. Poles fulfilled them partially. They also assured that they turned to the American company with a question about the possibility of installing covers for fuse panels. Additionally, minor improvements in the operation of the rescue system at Chopin Airport were recommended, which was done.
It is a task to possibly hold the participants of an accident accountable prosecutor’s office. This, however, did not find it appropriate to do so in this case. On the contrary, the crew of the machine was feted like heroes and received state decorations. The plane itself ended up donating parts and scrap. An emergency landing caused serious damage to the fuselage, the removal of which in such an old machine (24 years) was considered unprofitable. First, the repairable engines were sold. The rest of the machine was sold for parts a little over six months later. Two years after an emergency landing and dismantling of anything of value, it was cut into scrap.
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