Put Down the Landing Gear
Anyone who has read or watched the news this week has seen a lot of footage of a US Air jet that landed hard in the Hudson River after takeoff from New York. A few of the passengers were injured but none were killed. Most of the plane remained in one piece, and it floated. Ferry boats picked up passengers from the frigid water before they succumbed to hypothermia.
The usual pundits are heaping accolades on the pilot of the doomed plane who chose the Hudson River rather than some street full of buildings, and who managed to miss all bridges and river traffic with the doomed airplane. He and the passengers were extremely lucky to have survived. Most of the time a plane hitting water comes apart in several pieces and many of the passengers are killed by sharp metal edges and high speed impact, or drowned. They were very lucky. The wreckage has been hoisted out of the river today and we see the ripped up under side of the airplane. One engine was ripped off by the impact with the water and the other engine was ripped apart but still clinging to a wing. Much of the aluminum skin on the bottom of the plane was ripped apart. They were very lucky. Another plane crash into water is sometimes seen on one of those “Worst Video” disaster programs as the other plane cartwheels and kills half the passengers.
Badly damaged Airbus
Back in the late 1960s while Bob worked in the structural test engineering division at the Boeing Aircraft Company the 727 airplanes were the new thing. Unlike previous 707 planes the 727 had a much smaller wing that was efficient at high speed. Without power the small wing 727 would glide like a rock. When experienced pilots moved from the 707 to the new 727 many of them tried to land the new plane the way they had always landed the older 707s. Standard practice was to shut the engines down to idle and glide onto the runway. That didn't work with the 727 and several pilots came down short of the runway because the new 727 didn’t glide well or far. Engines used in the late 1960s took up to 30 seconds to spool up to full power from idle. Once the pilot figured out that he wasn’t going to make the runway, he couldn’t get power in time to save the plane from a crash landing short of the field.
Two of the crashed 727s came down in water, in San Francisco and Boston where the airport is next to the bay. Unlike the US Air crash in the Hudson, the 727s were prepared for a normal landing on the airfield. They had their LANDING GEAR extended. They suffered virtually NO DAMAGE at all other than salt water corrosion.
Boeing engineers who evaluate every crash of a Boeing plane concluded that the LANDING GEAR deployment saved the plane and the passengers. The landing gear is the strongest part of an airplane, and is the ONLY part of the plane that is strong enough to hit the ground, or the water, without suffering major damage. At 150 mph water acts almost like a solid, deflecting any attempted penetration. The landing gear skid first and then sink in while transferring huge momentum of the plane into the water without suffering structural failure.
Boeing structural engineers concluded that pilots had always previously been landing wrong in water ditch situations. Pilot training throughout the history of aviation tells pilots to keep the landing gear up and pretend the plane is a “flying boat” for a water ditch landing. Unfortunately a flying boat is much stronger and shaped different than the bottom of a regularly plane. A regular plane’s underbelly rips apart, the wings usually catch a wave, and the plane tumbles and tears apart into several sections. Even WW II fighter planes that ended up in water usually ended up upside down. After evaluating the 727 crash landing short of runways with the landing gear down, Boeing engineering concluded that pilots should always put the landing gear down and land as if its solid ground. A plane ditching in water with the landing gear down will remain intact and none of the passengers will be injured or killed. Somehow this jewel of safety information has not been transmitted to pilot training. Pilots are not trained to put down the landing gear for a water landing.
The US Air pilot who has received so many accolades in New York was very lucky, not very smart. He was lucky to land in calm water without waves to catch one wing first and flip the plane sideways. He was lucky that the engines dragged water uniformly. He was lucky that only the bottom of the plane was ripped apart by the force of the water. He was lucky that the top part of the plane held together. The landing gear is the only part of the plane that is strong enough to hit the water without severe damage. The plane that landed in the Hudson River was an Airbus rather than a Boeing plane, but the structural strength of the landing gear is universal to all planes.
Destroyed Airbus on a barge
There were some people injured on the US Airways plane. One woman suffered two broken legs. A stewardess was badly cut. Several other people were also injured. He failed to do the most important thing when landing on water, but got away without anyone being killed.
To the pilots who may read this, do some research. Find out about putting the landing gear down. And don’t try to pretend you are piloting a flying boat. It doesn’t work that way. If you don’t put down the landing gear people are going to be injured and perhaps many will be killed.
The usual pundits are heaping accolades on the pilot of the doomed plane who chose the Hudson River rather than some street full of buildings, and who managed to miss all bridges and river traffic with the doomed airplane. He and the passengers were extremely lucky to have survived. Most of the time a plane hitting water comes apart in several pieces and many of the passengers are killed by sharp metal edges and high speed impact, or drowned. They were very lucky. The wreckage has been hoisted out of the river today and we see the ripped up under side of the airplane. One engine was ripped off by the impact with the water and the other engine was ripped apart but still clinging to a wing. Much of the aluminum skin on the bottom of the plane was ripped apart. They were very lucky. Another plane crash into water is sometimes seen on one of those “Worst Video” disaster programs as the other plane cartwheels and kills half the passengers.
Badly damaged Airbus
Back in the late 1960s while Bob worked in the structural test engineering division at the Boeing Aircraft Company the 727 airplanes were the new thing. Unlike previous 707 planes the 727 had a much smaller wing that was efficient at high speed. Without power the small wing 727 would glide like a rock. When experienced pilots moved from the 707 to the new 727 many of them tried to land the new plane the way they had always landed the older 707s. Standard practice was to shut the engines down to idle and glide onto the runway. That didn't work with the 727 and several pilots came down short of the runway because the new 727 didn’t glide well or far. Engines used in the late 1960s took up to 30 seconds to spool up to full power from idle. Once the pilot figured out that he wasn’t going to make the runway, he couldn’t get power in time to save the plane from a crash landing short of the field.
Two of the crashed 727s came down in water, in San Francisco and Boston where the airport is next to the bay. Unlike the US Air crash in the Hudson, the 727s were prepared for a normal landing on the airfield. They had their LANDING GEAR extended. They suffered virtually NO DAMAGE at all other than salt water corrosion.
Boeing engineers who evaluate every crash of a Boeing plane concluded that the LANDING GEAR deployment saved the plane and the passengers. The landing gear is the strongest part of an airplane, and is the ONLY part of the plane that is strong enough to hit the ground, or the water, without suffering major damage. At 150 mph water acts almost like a solid, deflecting any attempted penetration. The landing gear skid first and then sink in while transferring huge momentum of the plane into the water without suffering structural failure.
Boeing structural engineers concluded that pilots had always previously been landing wrong in water ditch situations. Pilot training throughout the history of aviation tells pilots to keep the landing gear up and pretend the plane is a “flying boat” for a water ditch landing. Unfortunately a flying boat is much stronger and shaped different than the bottom of a regularly plane. A regular plane’s underbelly rips apart, the wings usually catch a wave, and the plane tumbles and tears apart into several sections. Even WW II fighter planes that ended up in water usually ended up upside down. After evaluating the 727 crash landing short of runways with the landing gear down, Boeing engineering concluded that pilots should always put the landing gear down and land as if its solid ground. A plane ditching in water with the landing gear down will remain intact and none of the passengers will be injured or killed. Somehow this jewel of safety information has not been transmitted to pilot training. Pilots are not trained to put down the landing gear for a water landing.
The US Air pilot who has received so many accolades in New York was very lucky, not very smart. He was lucky to land in calm water without waves to catch one wing first and flip the plane sideways. He was lucky that the engines dragged water uniformly. He was lucky that only the bottom of the plane was ripped apart by the force of the water. He was lucky that the top part of the plane held together. The landing gear is the only part of the plane that is strong enough to hit the water without severe damage. The plane that landed in the Hudson River was an Airbus rather than a Boeing plane, but the structural strength of the landing gear is universal to all planes.
Destroyed Airbus on a barge
There were some people injured on the US Airways plane. One woman suffered two broken legs. A stewardess was badly cut. Several other people were also injured. He failed to do the most important thing when landing on water, but got away without anyone being killed.
To the pilots who may read this, do some research. Find out about putting the landing gear down. And don’t try to pretend you are piloting a flying boat. It doesn’t work that way. If you don’t put down the landing gear people are going to be injured and perhaps many will be killed.
Labels: design responsibility, technology
posted by Bob | Sunday, January 18, 2009
11 Comments:
I like pie.
Bob,
That's interesting! What you say makes sense though. Water would act like a solid to any object impacting it @ 150mph. Landing gear is the strongest part of the aircraft. Finally, what you say about flying boats vs. land planes is a "DUH!"; one has a strengthened bottom, and the other does not. It would seem to me that this would be part of pilot training and disseminated via the AIM.
Though I never made it as a professional aviator, I did have the chance to compare Cessnas and Piper Warriors with an old Piper Arrow with the old Clark-Y (aka Hershey Bar) wing. The former airplanes would float down at idle, whereas the older Arrow needed 1700-1800 rpm to maintain the landing path. That took some getting used to! You pull the power to anything less than 1700 rpm on an old Piper Arrow (Hershey Bar wing version), you know it; boy, do you know it! The VSI points down right away, and you feel it. Fortunately, the piston engines used power up right away, so your descent could be arrested in time...
MarkyMark
Gear down would make sense for a ground landing, but on water you'd simply increase the chance that you'd flip it. In addition, you'd greatly increase the rate of deceleration and risk injuring passengers that way.
Sullenberger is a role model for all men. His hero's welcome home:
http://www.msnbc.msn.com/id/28825557/?GT1=43001
A good pilot is the many who don't fly an airplane into a gaggle of geese and crash it.
A good pilot is the one who arrives safely at his destination, not the one who destroys the plane in a crash landing in the river.
how would bob have avoided the geese?
assuming bob is a pilot
Note to anonymous:
The voice recorder shows that the pilots saw the flight of geese. They thought the geese would pass beneath the plane, but they made a mistake in judgment.
If their judgment had been more accurate they could have turned left or right. They could have pulled up, or maybe even down. Instead they continued on their collision course, hit the geese, and crashed the plane.
It was another obvious case of pilot error.
I can find no source supporting your claim that Boeing engineers endorse gear-down ditching procedures. Please provide your source of information. I've flown Boeings for 18 years, and I believe a gear down ditching would be worth researching. In fact, I have raised the question in training, only to be mocked, by those locked in ancestor worship. I would love to find a Boeing endorsement. I need more than a Blogger's opinion on the web. Thank you.
Note to Tim:
In the late 1960s Bob worked in Boeing's Structural Test Engineering Dept. which was loosely affiliated and co-located to some extent with Boeing Flight Test at the north end of Boeing Field in Seattle. Bob was not directly involved in the after-crash evaluations of airplanes that landed without damage in water with the gear down, but it was discussed around the Flight Test and Structures Testing Engineering groups. I thought at the time that Boeing was going to recommend the new procedure to all pilots.
I suspect now that Boeing apparently killed the gear down recommendation for political or legal reasons -- not structural or safety reasons. Like you say, many "experienced" people base their decisions on history and stupidity rather than good sense.
Maybe Boeing was afraid that a new landing procedure would encourage shyster lieyers to sue, where a crash that killed half the passengers could be written off as "pilot error."
Boeing does things for strange reasons sometimes. For example the engineers once recommended adding electronic speed controls for the windshield wipers of the 727 as a cure for broken pilot's windows that the wipers occasionally caused. Boeing killed the proposal reasoning that they didn't want owners of older airplanes to be told that their plane wasn't as good as the new planes with the redesigned wipers.
Most of the engineers who worked at Flight Test and Structural Test Engineering in the late 1960s are probably retired or dead now. I was pretty young then. I don't know if any of this "gear down" logic is anywhere else on-line or in Boeing's public publications.
P.S. To Tim:
Look up if you can the history of early 272 crash landings short of the runways in the first few months of 727 service. Check out records of, for example, a plane that landed in San Francisco Bay short of the airport. And one that landed short of Logan Field in Boston. Gear down, virtually no damage. (that's from memory)
Can pilots access NTSB safety investigations from previous decades? It should all be available.
IF the pilot landed with the gear down, the main gear would be snagged by the water slamming the nose of the aircraft into the river,and breaking apart. One reader kept saying luck luck luck. There may well been some luck involved but outstanding airmanship is what made this happen. How long would that aircraft float with the landing down? david ling
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