# Factual Question about the Hudson Rvr Crash **URL:** \ **Category:** Factual Questions\ **Created:** [January 16, 2009, 3:47pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606 "2009-01-16T15:47:56Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![corkboard](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@corkboard](https://boards.straightdope.com/u/corkboard)\ **Post date:** [January 16, 2009, 7:42pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/21 "2009-01-16T19:42:10Z")
It must have been one massive flock of birds. That particular Airbus is designed to be able to take off with a full load of passengers and fuel using only one engine, for just this sort of possibility. For both engines to have failed completely necessitating a controlled ditching, the likelihood of which is extremely low, the flock must have been huge. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [January 16, 2009, 7:53pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/22 "2009-01-16T19:53:07Z")
> [@AndrewL](#): > > In addition to the previous point about a mesh screen over the intake not actually stopping birds, it would be a disaster in icy conditions. A wire screen in front of the engine intake would be a perfect place for ice to build up, then break free and be sucked into the engine intake. Or block all airflow. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [January 16, 2009, 7:56pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/23 "2009-01-16T19:56:10Z")
> [@corkboard](#): > > It must have been one massive flock of birds. That particular Airbus is designed to be able to take off with a full load of passengers and fuel using only one engine, for just this sort of possibility. For both engines to have failed completely necessitating a controlled ditching, the likelihood of which is extremely low, the flock must have been huge. Worst-case scenario, couldn’t the same results be achieved with two geese? ---
**Author:** ![accidentalyuppie](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@accidentalyuppie](https://boards.straightdope.com/u/accidentalyuppie)\ **Post date:** [January 16, 2009, 8:12pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/24 "2009-01-16T20:12:02Z")
> [@UncleRojelio](#): > > The ferry dispatcher saw the accident and sent all ferries to the spot. The ferry boats practice water retrievals every week. And the plane did splash down directly across from a ferry terminal. I heard a ferry worker quoted as saying “I was really suprised because planes don’t usually land there but I figured we’d better go out and help them”. It takes a lot to faze some New Yorkers. THe first ferry was at the site a minute or three after the crash and was already loading passengers when the first police boats arrived. ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [January 16, 2009, 8:15pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/25 "2009-01-16T20:15:37Z")
> [@accidentalyuppie](#): > > And the plane did splash down directly across from a ferry terminal. I heard a ferry worker quoted as saying “I was really suprised because planes don’t usually land there but I figured we’d better go out and help them”. It takes a lot to faze some New Yorkers. > > THe first ferry was at the site a minute or three after the crash and was already loading passengers when the first police boats arrived. Keep in mind that this unflappable New Yorker had to keep her Ferry moving at the same speed the plane was drifting to ensure the transfer. She did a great job at reacting and do what needed to be done. One of many heroes yesterday. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [January 16, 2009, 8:22pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/26 "2009-01-16T20:22:22Z")
> [@corkboard](#): > > It must have been one massive flock of birds. That particular Airbus is designed to be able to take off with a full load of passengers and fuel using only one engine, for just this sort of possibility. For both engines to have failed completely necessitating a controlled ditching, the likelihood of which is extremely low, the flock must have been huge. My husband and I were wondering about that. Assuming it as two birds, one per engine, what is the probability of a bird strike fully disabling the engine along with a second bird strike fully disabling the second engine while being too far from a runway to land on it resulting in a water landing in which everyone survives? It seems pretty damn improbable, doesn’t it? I think even if some sort of screen could be designed to prevent this sort of thing, it is so unlikely that planning for it would have entailed cost and time that wouldn’t have been considered worth it. Nothing can ever be completely safe, so you plan for a certain probability of things happening, and this… well, I don’t think it rates very highly on most manufacturer’s risk assessments! ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [January 16, 2009, 8:23pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/27 "2009-01-16T20:23:09Z")
> [@corkboard](#): > > It must have been one massive flock of birds. I wouldn’t be surprised. I live not more than a few dozen miles from where this happened, and it’s not unusual to see flocks of hundreds of geese flying overhead in the winter. They’re not small birds either. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [January 16, 2009, 8:26pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/28 "2009-01-16T20:26:10Z")
> [@What\_Exit](#): > > Keep in mind that this unflappable New Yorker had to keep her Ferry moving at the same speed the plane was drifting to ensure the transfer. She did a great job at reacting and do what needed to be done. One of many heroes yesterday. You just had to go and do this didn’t ya? :rolleyes: The river is flowing, the airplane in in the river, the boat is in/on the river… Hummm What is the difference between the speed of the aircraft being carried along by the river and the speed of the boats being carried along by the river? That math is way to far above my pay grade. Would someone else please do it for us…?? :smack: ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [January 16, 2009, 8:28pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/29 "2009-01-16T20:28:51Z")
> [@GusNSpot](#): > > You just had to go and do this didn’t ya? :rolleyes: > > The river is flowing, the airplane in in the river, the boat is in/on the river… Hummm What is the difference between the speed of the aircraft being carried along by the river and the speed of the boats being carried along by the river? > > That math is way to far above my pay grade. Would someone else please do it for us…?? :smack: What is your problem with it? Two different shaped objects in flowing water do not move at the same speed. Perhaps you are not use to boats and don’t realize how tricky it can be to transfer people between them. BTW: I have been on that part of the Hudson River in a small wooden sailboat and we had a hard time tying up to the [Clearwater](http://www.clearwater.org/)and decided going between boats was too dangerous. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [January 16, 2009, 9:53pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/30 "2009-01-16T21:53:17Z")
To answer the OP, yes, it would help a bit to land downstream rather than upstream - the relative velocity of the aircraft vs. the water at impact would be less, and so would the deceleration forces. But available straight “runway” length and obstacle clearance would easily trump that consideration. Just ftr, a seaplane setting down on water, as it’s designed to, is still called a “landing”. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [January 16, 2009, 9:55pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/31 "2009-01-16T21:55:22Z")
And to follow on, a plane landing on a treadmill running at the same speed would not spin up its tires. A plane landing downstream on a very swift current, at the same speed, would not decelerate at all. ---
**Author:** ![corkboard](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@corkboard](https://boards.straightdope.com/u/corkboard)\ **Post date:** [January 16, 2009, 9:55pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/32 "2009-01-16T21:55:59Z")
> [@Ethilrist](#): > > Worst-case scenario, couldn’t the same results be achieved with two geese? Two perfectly placed geese, sure. ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [January 16, 2009, 10:21pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/33 "2009-01-16T22:21:58Z")
> [@What\_Exit](#): > > What is your problem with it? Two different shaped objects in flowing water do not move at the same speed. Perhaps you are not use to boats and don’t realize how tricky it can be to transfer people between them. I think that’s what he’s saying–it introduces a \ motion problem and I know my mind shuts down when faced with one of them. He was saying he’s not equipped to calculate it. I think. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [January 16, 2009, 10:54pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/34 "2009-01-16T22:54:03Z")
> [@gigi](#): > > I think that’s what he’s saying–it introduces a \ motion problem and I know my mind shuts down when faced with one of them. He was saying he’s not equipped to calculate it. I think. Ah, no. 😛 ---
**Author:** ![vison](https://avatars.discourse-cdn.com/v4/letter/v/e47774/32.png) [@vison](https://boards.straightdope.com/u/vison)\ **Post date:** [January 16, 2009, 11:35pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/35 "2009-01-16T23:35:06Z")
thank you for the answers. I guess I should have thought of it myself. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [January 16, 2009, 11:49pm UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/36 "2009-01-16T23:49:53Z")
> [@mnemosyne](#): > > My husband and I were wondering about that. Assuming it as two birds, one per engine, what is the probability of > > a bird strike > fully disabling the engine > along with a second bird strike > fully disabling the second engine > while being too far from a runway to land on it > resulting in a water landing > in which everyone survives? > > It seems pretty damn improbable, doesn’t it? Perhaps you’re thinking of the odds of two birds, the only two birds in the entire sky just happening upon a plane in just the right positions that each one went into each engine at a perfect angle at the same time. Pretty unlikely, I’ll grant you.[sup]\*[/sup] But if a large _flock_ of closely-spaced birds intersected the plane’s flight path, that’s a different story. It would be unusual if each engine DIDN’T get hit by one of them big buggers. Of course, I have no evidence that either scenario occurred. We’ll just have to wait for the investigation. * * * - But when you consider how many birds and planes and takeoffs there are in the world over the years, maybe not so much. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [January 17, 2009, 12:03am UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/37 "2009-01-17T00:03:33Z")
They test all jet engines by firing frozen turkeys at them. If they can’t survive that test they are not certified for airliners. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [January 17, 2009, 12:03am UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/38 "2009-01-17T00:03:38Z")
> [@What\_Exit](#): > > What is your problem with it? Two different shaped objects in flowing water do not move at the same speed. Perhaps you are not use to boats and don’t realize how tricky it can be to transfer people between them. As someone who is “use” to boats I can tell you that you are quite mistaken. Objects in the water will all move together unless there is wind affecting them differently. If there was a significant amount of wind then it would probably affect the ferry more than the airplane as the airplane was mostly submerged. Still, unless the wind was really strong, maneuvering the ferry and keeping it close to the airplane is quite trivial for any experienced master. Ferry operators are quite used to strong wind and currents and it is more difficult to approach a (stationary) dock than a floating object which is moving with the current. In significant wind, with the tail up, out of the water, the airplane would have ended moving with the current , facing into the wind. If there is strong wind then the fery operator is going to have to take that into account when approaching but I doubt wind was that strong. Waves would present much more danger as there would be danger of collision. From the photos it looks like there was not much wind and so the ferry and the airplane would just float together with no additional action from the ferry operator. ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [January 17, 2009, 3:00am UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/39 "2009-01-17T03:00:00Z")
> [@Bijou\_Drains](#): > > They test all jet engines by firing frozen turkeys at them. If they can’t survive that test they are not certified for airliners. No, they don’t. They fire fresh chickens. A frozen turkey would be indistinguishable from a bowling ball. That’s not a test, it’s a demolition. The “Chicken Guns” that several government agencies and contractors use to test bird strikes are quite real. They provide valuable data on the effects of bird ingestion. And depending on the specification being tested, the engines don’t necessarily have to survive the test. In most cases, what they are looking for is a “safe” mode of failure. That is, fan blades may be broken and the engine may suffer catastrophic failure. But no matter what happens inside the engine, no pieces may penetrate the case. A piece of turbomachinery shrapnel would be quite deadly if it were allowed to escape. As much as I trust airline safety, sitting in the row in line with the fan face always makes me a teeny bit nervous…or at least the idea rattles around in the back of my mind the whole flight. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 17, 2009, 3:55am UTC](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606/40 "2009-01-17T03:55:08Z")
Pilot type … Going back to the OP’s question about landing into or against the current. There is no practical difference. Your touchdown speed is about 140 mph. That “fast” current was 3 mph. So your speed relative to the water is either 137 or 143 mph depending on with vs. against. As a matter of academic nitpick, those numbers are indeed not equal. As a practical matter of flying, the difference is ~4%. In other words, not enough to notice, net of all the other variables in the process. [Previous page](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606.md?page=1) [Next page](https://boards.straightdope.com/t/factual-question-about-the-hudson-rvr-crash/481606.md?page=3)