Untrimmed weeds caused problems that could have led to a crash one morning last June when five planes tried to land in poor visibility at Ben-Gurion International Airport, according to a report by the Transportation Ministry.
The report, which Haaretz obtained yesterday, spreads the blame among officials at the Israel Airports Authority, ground technicians, air traffic controllers and pilots.
Weeds apparently interfered with the instrument landing system (ILS), the ground-based system that generates a path for planes descending to land. Pilots reported problems in five of seven approaches they made.
One plane landed in borderline visibility, one landed on an alternate runway and three were diverted to other airports, according to the report.
During poor weather such as low clouds or fog that prevents pilots from seeing the ground, planes land using automatic systems that use data provided by the instrument landing system.
On the morning of the incident, five planes attempted seven approaches using the ILS on Runway 26. In five approaches the pilots reported glitches in the navigation system. In two other approaches the pilots told the control tower they were going to circle due to poor visibility.
One of the planes landed in limited visibility, three were diverted to other airports, and another circled before landing on a different runway that had been opened.
An air traffic controller at Ben-Gurion's control tower saw on his radar that two planes - El Al flight 104 from Toronto and Israir flight 022 from New York - were coming in too low. He informed the leading plane's pilot and was told that the plane was in automatic landing mode and being guided by the ILS.
The controller then realized that because of a malfunction, the two planes were arriving at a dangerous angle, given the hilly terrain east of the airport. He therefore redirected them to Larnaca International Airport in Cyprus.
Had the planes kept coming in at the angle recommended by the instrument landing system, they could have hit the ground before reaching the runway, the report said.
The Israel Airports Authority investigated the possibility that thick and high vegetation near the ILS sensors obstructed the signals to the planes.
Initial attempts to reset the system failed; it returned to normal only after the ground around it had been cleared.
"On June 3, 2009, Ben-Gurion Airport was operating under poor visibility due to heavy fog in the area of the airport," the airports authority said in a statement. "Two airplanes, belonging to El Al and Israir, attempted landings on Runway 26, which is equipped with ILS.
"As they were approaching the ground, a traffic controller at the control tower alerted the pilots about the possibility of error in their approach angle. They were aware of the error but couldn't land at the airport due to poor weather. The slight malfunction in the ILS was fixed that day."
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