Factual Question about the Hudson Rvr Crash

FTR, I think the pilot did an outstanding job no matter what the circumstances

I believe the plane landed with the current on the Hudson. Would have been easier, harder or no difference if the plane had landed against the current?
(FTR, I am not asking if it would have been easier to land the plane on a giant treadmill, or a frictionless surface)

Anybody know how fast the Hudson flows near the George Washington Bridge?

I’d really, really like to see a video of this thing landing, but if we haven’t seen it yet, I’m assuming it didn’t get recorded.

I would wager that landing with the current helped minimize a bow wave at least a little, and to minimize the resistance against the water, which would have helped to avoid damaging the plane, causing a more sudden stop, or for it to submarine, but given the relative speed of plane & water, I’d say it’s probably a pretty small difference.

I have another factual question if it’s not a hijack – I don’t want to open another thread. I’ve read several accounts, and they all mention the ferries and other boats that came to the rescue of the passengers. Was there some kind of organization to this rescue effort? Did someone put out a distress call for all available vessels?

But what if the Hudson were on a giant treadmill?

The ferry dispatcher saw the accident and sent all ferries to the spot. The ferry boats practice water retrievals every week. Of all the stuff I’ve read since yesterday about this accident, I don’t recall now where I read those facts but that is what I read.

River currents are typically only two or three knots. I doubt whether that would make a difference in this landing.

The Hudson is very tidal at the GW Bridge and south: http://www.mobilegeographics.com:81/locations/2121.html?y=2009&m=1&d=15

At the Bridge yesterday the tides were:
2009-01-15 2:54 PM EST **-0.00 knots **Slack, Ebb Begins
2009-01-15 4:52 PM EST Sunset
2009-01-15 6:18 PM EST **-2.45 knots **Max Ebb

So it looks like the current was probably close to only 1 knot.

The plane came down close to the USS Intrepid. Next to the Intrepid are the docks for the Day Liners, a NY Ferry service and another Ferry service operates nearby. Additionally the NYPD has many fast boats and the Coast Guard was only 10 miles away tops at the Sandy Hook, NJ station. One Ferry Pilot saw the plane land and headed over immediately. One of the nearby ferry dispatchers, dispatched all of his available boats over to the plane within minutes.

Finally, NYC has actually run some drills for emergency water rescues apparently that include the ferry operators. I don’t know any details on this though.

Then the plane would never land. :smiley:

I don’t want to start another thread, so I hope it’s okay to ask this question in here.

Apparently a flock of birds, possibly Canada geese, caused the accident. Why are there no screens over the engines? It wouldn’t have to be a fine mesh, which might interfere with airflow, but surely a 2 inch by 2 inch wire mesh would work? Or not. Anyone know why they don’t do this?

My understanding, based on nothing more than hearing it discussed on the radio this morning, is that given the size of the object (bird) and the speed on impact, the only difference would be that you would have both bird parts and mesh fragments sucked into the engine. IOW, there isn’t a mesh that is both strong enough to prevent the event and also small enough so as to not impede airflow.

So says some random guy on CNN Radio, as reported by me, a stranger on a message board. Can’t get more factual than that!

Well, my wife heard on the Bob & Sheri radio program this morning that it’s a good thing it was so cold; the water was harder than it would have been if it were warm. :confused:

So said an anonymous caller, to a radio show run by blithering idiots, relayed by a non-science-or-avaition-trained spouse to yours truly, who posts it under a pseudonym to an open message board? How’s that for truthiness?

Thanks for the answers, I really didn’t think it would make much difference. I am sure calm water would be better than choppy water with whitecaps.

While it is true that water is denser at colder temperatures (well, between 4C and higher… it actually reduces in density as it approaches 0C from 4C), the fact is the plane is always denser than the water, and by such a large amount that I very much doubt that the difference would impart any additional boyancy to the plane. I’m not seeing how cold water could be “a good thing” - in fact, it’s to blame for the mild hypothermia some of the passengers might be suffering from!

This mild injection of truthiness comes courtesy of a tired and hungry student waiting for her next class - which is actually a thermodynamics course, but we’re talking about gases at the moment!

That would also impede the airflow. It may not seem like much, but jets suck in a lot of air and any screen is going to affect performance.

Let me vouch for that answer as a propulsion engineer.

There is nothing practical you can do to prevent a commercial engine from ingesting a bird that is determined to enter the intake. Any screen more robust than some flimsy chicken wire will produce unacceptable pressure losses in the incoming flow. Airlines depend on wringing every last bit of efficiency possible from their engines, and the performance hit from a FOD* screen that could stop a goose would be massive.

Military aircraft may have certain FOD avoidance measures built in. But these usually rely on being able to take advantage of a certain length of inlet duct to help separate foreign objects from the air stream. Commercial airliners don’t have embedded engines with long inlet ducts to work with a FOD rejection system. That’s because, again, they need all the efficiency they can get. And a near zero-length inlet on a pod-mounted engine is the best way to wring maximum performance from your jet.

They do use FOD screens in ground testing of engines. You may see a conical mesh cover put over the inlet of an engine on a thrust stand. But those are meant to stop the relatively casual ingestion of a stray bolt or pebble. They are not what you would need to withstand a 10-lb bird hitting the engine face at 200 mph. It’s like fencing equipment. The mesh face mask will help stop a foil from hitting you in the eye, but it won’t do anything to keep you from being shot in the face with a .45.

So, because there’s no practical way to keep a bird from getting in the turbomachinery, the best the engineers can do is design the engine to be as tolerant as possible of ingesting such material. When you consider how complicated turbine engines are, they’re doing a remarkable job if they can have any success at all. The fact that an engine can ever withstand a birdstrike and keep operating is amazing to me. But they’re not bulletproof, so sometimes you have what happened yesterday. And geese are pretty damned big…so yesterday’s accident was hardly surprising (if it happened they way everyone thinks).

*Foreign Object Damage

Googled pictures of birdstrike damage show some impressive holes in windshields and fuselage. I don’t think a screen will stop a determined bird.

As far as the water temperature affecting the outcome of this crash, I’d say the cold helped… if this had happened in the summertime, there would have been sail- and motor-boats all over that river, which would have complicated matters immensely, particularly in the rescue stage, if the small boats tried to help out.

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.

Though this has been answered, I’ll still weigh in. Years ago I saw a Cessna 206 that had taken a couple of geese to the wings. The one that hit the left wing nailed the leading edge dead on and actually punctured it. So I’d have to say that no practical screen could possibly be strong enough. (And keep in mind the plane I saw flies at about a fourth of the speed of an airliner.)

I supposed you could heat the screens, but yeah. My first thought was of the FOD danger these screens may present, as opposed to the chance of birdstrike.

How many engines are disabled due to birdstrike per year?