Expert: Paul Soderman - 5/4/2011

Question
In light of the raid on Osama bin Laden's compound, how does one carry out a surprise attack using helicopters? Wouldn't they be heard long before anyone could rappel out of them? How does a helicopter get muffled?

Answer
You are right Eleanor, helicopters are noisy and cannot be muffled.  But the Blackhawk flies pretty fast:  222 mph (357 km/h, 325 ft/s).  They also fly very low.  So if they used the terrain to advantage and got within, say a half mile of the target before they had line of sight to the target, the sound would arrive only 8 seconds before the helicopters. In the middle of the night that is not very much time to set up a good defense. It might take half a minute or a minute to decide it wasn't Pakistani helicopters, get dressed, armed and out the door in the middle of the night. Plus, the helicopters themselves can return fire if necessary before anyone has to rappel.  I don't really know how the attack was done, but the Navy Seals probably had a plan similar to what I have described.
Paul