Tailwinds and wet runways are threats to landing planes
Eva C. Komandjaja and Muninggar Sri Saraswati, The Jakarta Post/Jakarta
Heavy rain and strong tailwinds are two conditions that pilots dread during landing.
A study conducted by scientist Gerard van Es and test pilot Arun Karwal of the Netherlands' National Aerospace Laboratory (NLR) in 2001, showed that tailwinds played a key role in 33 accidents involving large (5,700 kgs or higher) turbojets.
The study also found 31 of the 33 cases took place during landing, with 19 of them involving wet runways.
The two conditions were present in the plane accident involving a Lion Air MD-82 aircraft at Adi Sumarmo International Airport in the Central Java town of Surakarta on Tuesday, which left at least 26 people dead and 75 others injured.
A special team from the National Transportation Safety Committee (KNKT) is still searching for the cause of one of the worst plane accidents in the country.
Lion Air spokesman Hasyim Arsal Alhabsi said on Wednesday that strong tailwinds were believed to be the main cause of the accident, the severity of which was heightened by the plane's collision with the airport's safety barrier and a cemetery fence.
"Had the plane skidded off the runway only, no lives would have been claimed. But it was fate, we could not avoid it," Hasyim said.
However, he said, bad weather as the cause of the accident was only a theory the company had developed after checking the accident site.
Weighing 67,812 kgs, the MD-82 aircraft may encounter problems if tailwinds during landing measure more than 10 knots.
Tailwinds reached more than 10 knots in 15 of 33 cases studied by the NLR, although the MD 82's operational limitation does state that the aircraft cannot withstand tailwind velocity of more than 10 knots.
Separately, head of the Meteorology and Geophysics Agency (BMG) Gunawan Ibrahim said his office had always provided real-time weather information to airport authorities.
Pilots use the information to determine whether to go ahead, or cancel a flight in the case of dangerous weather.
Hasyim dismissed speculation that the ill-fated aircraft was not fit to fly, despite the fact that it was made in the early 1980s. Boeing, which acquired aircraft maker McDonnell-Douglas, ceased producing the MD-80 series in 1999.
"You can check to see how many MD-82s are still flying -- there are hundreds of them, and it's not true that this plane cannot be used anymore," Hasyim said.
He added that all Lion Air jets underwent regular checks and were maintained according to International Civil Aviation Organizations (ICAO) regulations.
"We know that the plane was in good repair, it was checked just before the Idul Fitri holiday in early November as required by the government," Hasyim said.
The recent crash brings to 11 the total aircraft accidents involving MD-82s in the world, since the early 1980s.