1. Hi Captain Lim, With the Airbus A320 miraculous landing in NY today (1/15/09) and the crash of another during a test flight last month for Air New Zealand, do you think there is a serious unknown problem with the airplane similar to that of the rudder problem the Boeing 737 had during the 90s? Thanks, Andrew.
2. Hi Captain Lim, What happens to this aircraft? Is this aircraft salvageable? Thanks. Eapen
3. Dear Captain Lim, Happy New Year! Thanks for the consistency in your website. I have the following questions!
a. Are planes designed to ably land on water in a crisis? With the landing gear down or not?
b. How could a plane like the A320 that has just taken off be able to glide? Is it designed that way?
c. If the captain had attempted to land on an airstrip as advised by the air traffic control, do you think they would have made it?
d. If a plane lands on water, how long is it designed to stay afloat? Robert.
Hi Andrew, Eapen & Robert,
Of course, it is widely reported now that the Airbus A320 was brought down by a flock of birds and not of any unknown problem similar to the Boeing 737 rudder trouble you mentioned.
Bird strikes are some of the risks that can be potentially disastrous to any airplanes taking off. The pilot’s skill is the last bastion to such a disaster and Captain ‘Sully’ has done an incredible job of saving the lives of 155 people on board the Airbus A320. My hat off to him!
I wrote previously that the Boeing 777 engines can withstand bird-strikes well because all modern jet engines are subjected to the “chicken gun” test before certification. Federal Aviation Administration (FAA) stipulates that planes must be able to withstand a strike from an 8lb (3.6kg) bird.
So large passenger jets can safely withstand being hit by at least a 4lb (1.8kg) bird but problems can arise with flocks of small or larger birds. Up to date, about 219 people have been killed worldwide as a result of bird-strikes since 1988
Yes, planes are being struck very often by birds but you don't hear about them so often because they are designed to take these impacts. Once you get to large birds striking at a critical moment, that's where the dangers are. According to the experts, a 12lb goose struck by an aircraft at lift-off would generate a force equivalent to a 1,000lb object being dropped from a height of 10feet (3m).
As regards to the Airbus A320 that crashed off the coast of France, the cause of the accident is not yet clear. A Civil Aviation Authority spokesperson stated that the incident does not cast any doubt on the airworthiness of the A320 design, a popular aircraft (there were about 3,117 A320 orders since its introduction around 15 years ago) which has been involved in only ten fatal accidents since its introduction in 1987.
Answer to Eapen
Q: Whether the Airbus A320 is salvageable?
A: It is difficult to say whether the plane is salvageable. It depends on the extent of the damage, but since it has sunk below the water level, I believe it is unlikely that the plane would ever fly again. The previous successful ditching of an Indonesian Garuda Boeing 737 (see this post ) was a write-off.
Answers to Robert
Q: Are planes designed to ably land on water in a crisis? With the landing gear down or not?
A: Airplanes are designed to withstand a well executed ditching with the gears up. (Read one of my earlier post here.)
Q: How could a plane like the A320 that has just taken off be able to glide? Is it designed that way?
A: Most planes are designed to glide with the engines off. The success of the glide would depend on the altitude of the planes – the higher the better. I think USAir Flight 1549 was in the worst situation when the engines were completely lost. I believe it may have partial power when it sustained the initial damage or else it would not have sufficient height to glide down safely or carry out a controlled ditch.
Q: If the captain had attempted to land on an airstrip as advised by the traffic control, do you think they would have made it?
A: Captain ‘Sully’ probably would not have made it. That was why he chose to ditch onto the Hudson River.
Q: If a plane lands on water, how long is it designed to stay afloat?
A: If the plane had not sustained any structural damage, it should stay afloat just like a boat. However, if there are any leakages, then it would gradually sink. One of potential source of any leak from the body is from the outflow valve – the outlet to depressurize the plane after landing. (The emergency drill requires that this valve and other avionic valves be closed in a ditching situation through the activation of a "Ditching" switch in the cockpit)
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