Airports already bulldoze bird nests and send dogs to chase off flocks, but engineers are trying new technologies to scare away birds in flight, including using landing lights as strobe lights, the vice chairman of the National Transportation Safety Board said Monday.

The official, Robert L. Sumwalt, spoke on the eve of Tuesday’s safety board hearing on the crash of US Airways Flight 1549, which took Canada geese into both engines shortly after takeoff from La Guardia Airport on Jan. 15 and glided into the Hudson. All 155 people on board survived.

Mr. Sumwalt said turning the landing lights into strobe lights could make a plane, closing in on the birds at more than 100 miles an hour, more conspicuous to them. But, he said, that is only one solution that should be investigated.

“Maybe there’s some other technology out there, a radar that some innovative company can come up with to zap the birds out of the way,” Mr. Sumwalt said in an interview. Some pilots believe that birds try to avoid emissions from the planes’ on-board weather radar, he said, and “we need to find out, is that an urban legend or is there some truth to that?”

“We need to be innovative when we’re looking for solutions here,” he said.

US Airways Flight 1549 had these monstrous birds fly into its engines.

Clearly, people have thought about solutions to flying aircraft near birds. As mentioned in the article, people already attempt to control the bird population near airports by destroying their nearby habitats. However, in the case of the Canada geese in US Airways Flight 1549, habitat destruction would not be practical because Canada geese are migratory in nature, which means they do not have a particular habitat to destroy (wildlife conservation advocates are probably shaking their heads in disgust at that).

Also according to the article, there are regulations in place for aircraft engine design that considers birds flying into them:

Another area to be covered in the three days of safety board hearings is how engine standards are set. There is a rule for how big a bird an engine must be able to take in and spit out while continuing to produce thrust, and another for the maximum size it must be able to take in without breaking up and throwing off dangerous shrapnel. The hearings will look into whether engines can be built to withstand birds as big as the Canada goose. Mr. Sumwalt said the answer was probably not.

If only there was a non-destructive solution to birds disrupting aircraft (such as a scarecrow for all types of birds) …

(Image from Wikipedia)

Impulse Equation

Impulse is another word for change in momentum, and is defined as force multiplied by time. Let’s consider two cases with the egg toss example:

1. You catch the egg with your arms and hands rigid (which means they do not move as the egg is caught). The egg’s motion comes to a complete stop when it hits your hands (and the insides of the egg are probably all over your hands as a result).
2. The egg is tossed at you at the same speed as in Case 1, and you catch the egg while moving your hands back along the motion of the egg, until the egg comes to a complete stop.

In both cases, the change in momentum of the egg is the same, because the egg’s initial speed and final speed (coming to a halt) are the same. What’s different between the two cases are the force applied to the egg, and the amount of time it takes to bring the egg’s motion to a stop.

In Case 1, the time that the egg took to come to a stop is extremely short: it was flying in the air at the speed at which it was thrown, and a split second later it came to a stop as it hit your rigid hands. Since the impulse of the egg remains constant, this means that the force acting on the egg during this split second is extremely large, which inevitably brings the egg to its doom and causes it to break.

On the other hand, in Case 2 the time in which the egg comes to a stop from it’s initial flying-in-the-air speed is much longer, because you were smart and moved your arms and hands with the egg as you caught it to bring it to a stop. By the same reasoning that the impulse remains constant, a long time implies that the force acting on the egg during that time is small. This significantly smaller force acting on the egg keeps it from breaking (if the force is small enough).

This principle of impulse to protect objects from breaking can be seen in many everyday devices. Some examples include airbags in automobiles, landing pads on the ground for gymnasts, and boxing gloves. The main idea behind all of these devices is that they deform when something hits them, which effectively increases the time required for a change in momentum, and therefore reduces the force acting on the incident object (in these cases, a person) onto the deforming safety device.