How Hudson Hero - Sullenberger and his Passengers - Walked on Water
Ken Alabi.

The pilot Chelsey Sullengerger is not only practically responsible for the lives of 155 individuals today, he has also saved the mood of the nation for the celebrations planned for Tuesday. The atmosphere next week would have been severely dampened had those lives been lost on Thursday. I expect Sullenberger to be invited to the inauguration, if not for saving the festivities but also because his actions are a reflection of the American Spirit that never gives up and stares adversity with a can do attitude.

A brief look at what happened. To note, there is no record, to my knowledge, in the database of aviation accidents, in which a commercial jet of that size and capacity has been set down on water that successfully (the engines did indeed break off). Large aircrafts usually break apart on water impact or torpedo in as one piece (actually most pilots have the instinct to try to achieve the break up since this increases survivability). Since this is a joyous article I will not burden users with a list of similar events that ended differently. I will only try to explain in a non technical way what he accomplished. However, only Sullenberger can speak for himself and/or possibly fill in the details. And he will be well debriefed and probably go on to share his unique perspective based on this event with other pilots and aviation prefessionals worldwide.

How It Happened (Engineer's Perspective)

Airplanes are heavy objects. They fly based on the Bernoulli principle that generates lift when objects of a specific shape moves rapidly through air. The specific shape is typically an airfoil with a dome shape usually characterized by a greater curve at the top of the component. Forward momentum is necessary to generate this lift. If an aircraft loses speed, it drops like a stone (if if doesn't go fast enough, it stalls or intermittently threatens to drop like a stone). As a result, landing an airplane is an attempt to balance the need for enough speed so the aircraft does not drop or stall and not too much speed so that it can stop within reasonable distance. Basically, wings are the airfoil-shaped lift mechanisms, engines provide thrust, and the body also called the fuselage is shaped for minumum drag. During flight we need less wing since they increase drag, and during landing we want more wing - hence flaps are used for most heavy aircraft. We can think of the flaps as providing more wing surface when needed. (They also usually serve as wind breaks after landing.) These things all work together, on a consistent basis day in and out and there is hardly any need for anyone to develop a fear of flying based on this simplified summary - the technology is pretty much regular at this point.

Now, what happens when an aircraft already in flight loses the power to generate speed necessary to maintain lift (the pilot's nightmare)? What pilots are taught to do is use gravity for momentum. This means using the altitude they have achieved to obtain forward momentum or glide and try to find the best landing spot for the plane. Depending on the features available on the craft, they also slowly jettison their fuel. Most pilots have chosen water in this scenario because the impact is softer. Ground impact usually results in complete disintegration accompanied by a magnanimous conflagration (sorry, this describes it best). Water landing is only slightly better. Virtually all have resulted in either a break up or a wholesale sudden conversion into a submarine only without the pressure seals.The break up may still also be accompanied by some combustion. Sometimes, a few passengers walk away from the breakup scenario and there are statistics that try to correlate seat position and highest survivability for those who wish to research this further.

What Sullenberger did is unprecedented. He did not have a lot of altitude to maneuver a powerless aircraft. He apparently also set the plane down at the perfect angle such that it did not break up or tunnel into the water (think how to skip a flat stone on still water - it has to be thrown and spinned at the right angle to glaze off the surface). It takes an individual who is an extremely skilled pilot on multiple aircraft types, and is so attuned to his craft to accomplish that (and even then possibly some additional good fortune - right surface pressure and conditions, little tide or roughness, good weather, and low winds to list a few). Not surprisingly, this is an individual who has been flying apparently since the age of 14, was a former air-force pilot, and is an aircraft safety consultant. A short description of his profile is included below for well deserved recognition.

Pilot's Profile

• Chelsey Sullenberger III has a bachelor's degree from the Air Force Academy and masters from Purdue and Nothern Colorado and was recently named as a visiting scholar to UC Berkeley's Center for Catastrophic Risk Management. He has been a US Airways pilot since 1980.
  
• Since 2007, he has run a safety consulting firm, Safety Reliability Methods, Inc. He served about seven years as an Air Force fighter pilot, attaining the rank of captain
  
• He has served as a flight instructor, Air Line Pilots Association safety chairman, accident investigator and national technical committee member and has investigated aviation accidents for the Air Force and National Transportation Safety Board and helped developed new protocols for airline safety. 

So while the festivities continue next week, as they should, and we slowly forget the tragedy just averted, in flight colleges all around the world where techniques are being taught, new pilots will now know for sure that it is possible to land a large sized commercial jet on water and save 100% of the lives on board without any power at all.

Ken has a Ph.D in mechanical engineering from Stony Brook University, works on multi-disciplinary design software for aircraft and aerospace systems, is a professional member of the American Institute of Aeronautics and Astronautics (AIAA), and a Long Island section committee member.

References

1. Inquistr Article, A320 Pilot Chesley Sullenberger’s Other Jobs: Accident Investigator and Safety Lecture , http://www.inquisitr.com/15441/a320-pilot-chesley-sullenbergers-other-jobs-accident-investigator-and-safety-lecturer/

2.Time Magazine Article, Two-Minute Bio: Chelsey B. Sullenberger III.  http://205.188.238.109/time/nation/article/0,8599,1872247,00.html

3. CBS News Article, Hero Pilot Going to Inauguration? http://www.cbsnews.com/stories/2009/01/17/earlyshow/main4729438.shtml

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