How, exactly, did US1549 land on the Hudson?

Danny Beckett
  • How, exactly, did US1549 land on the Hudson? Danny Beckett

    A comment by @AsheeshR says:

    The Hudson River Landing was due to a combination of piloting skill and an autopilot system that was engaged right till impact and kept the plane in a controlled descent within a safe flight envelope.

    It was an Airbus aircraft, so the autopilot has priority over pilot input, but how exactly did the autopilot play a role in getting them down safely?

    What exact procedures did Sully and the crew follow when landing? Was there anything in addition to standard ditching procedures, that might have contributed to them landing in one piece?

  • anything that helped? Luck, pilot skill, luck, just the right weather conditions, luck, nerves of steel, and some more luck.
    And they probably managed to get the aircraft so slow at just the right moment that they hit the water at just the right angle and minimum sheer forces to not break up.

  • There is not much training for situations like that because they are very rare and the simulators cannot teach accurately what to expect when a plane touches down on water.

    The captain in this situation got almost everything right for a water landing, as he kept the nose up and wings level, he let the tail hit the water first slowing the plane down enough so it survived the impact.

    I'm not sure autopilot played much role in this if any, because there was no runway length and reverse thrust to concider.

  • The NTSB report is a great resource when looking for information about an incident like this.

    There is an Engine Dual Failure Checklist discussed starting in section 1.17.1.2 of the report. This includes steps to attempt restarting the engines, and further steps depending on whether or not the engines can be started, and finally steps to help prepare for a forced landing. Pilots train on engine failures regularly, so they are already familiar with the procedures. The report discusses how their actions compared to what the checklists say. Since the incident occurred at such a low altitude right after takeoff, they didn't have time to complete all of the steps. They did what they had time for, and had to make quick decisions about what their options were.

    The report also discusses in section 1.17.3.2 the ditching training the pilots received. There was guidance in the manual, but no specific scenarios included in their simulator training.

    The autopilot is great for use in normal situations. However, as soon as anything is going wrong, the pilot should take control of the plane. You do not want to take time to figure out "what's it doing now" in a difficult situation. So in this situation, the autopilot probably disconnected when the engines went out, or was manually disconnected by the pilots.

    Section 1.6.3 talks about the flight envelope protections. I believe these protections are what you are referring to when you say that the autopilot has more control. They are designed to protect the plane from stalling or otherwise exiting controlled flight. Because the pilot was able to start the APU to provide electrical power, the plane remained in the "normal law" mode where these protections were available. This limits the control the pilot has in order to protect the plane, in the sense that the plane will override pilot inputs to avoid dangerous situations.

    Section 2.7.2 discusses the impact of these protections in this case.

    The airplane’s airspeed in the last 150 feet of the descent was low enough to activate the alpha-protection mode of the airplane’s fly-by-wire envelope protection features...

    Because of these features, the airplane could not reach the maximum AOA attainable in pitch normal law for the airplane weight and configuration; however, the airplane did provide maximum performance for the weight and configuration at that time...

    The flight envelope protections allowed the captain to pull full aft on the sidestick without the risk of stalling the airplane.

    An interesting point in the report is that Airbus certified the plane to be able to land on the water intact under certain conditions. Here is how the actual conditions compared to the certified conditions.

    Section 1.6.7

    enter image description here

    The report mentions that it would be extremely difficult to meet all of these requirements in an airplane with no power. The values that are higher, notably the mass and descent rate, are factors in the damage the airplane received.

Related questions and answers
  • A comment by @AsheeshR says: The Hudson River Landing was due to a combination of piloting skill and an autopilot system that was engaged right till impact and kept the plane in a controlled descent within a safe flight envelope. It was an Airbus aircraft, so the autopilot has priority over pilot input, but how exactly did the autopilot play a role in getting them down safely? What exact procedures did Sully and the crew follow when landing? Was there anything in addition to standard ditching procedures, that might have contributed to them landing in one piece?

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  • How does autobrake work? Gabriel Brito

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  • The major reason that lead Aeroflot Flight 593 to crash was the partial disengagement of the of autopilot (by the pilot's kid who was in the cockpit) which could have been avoided if the pilots were more familiar with the Airbus 310-100 or there was an audible alert. Do new Airbus aircrafts have an audible alert in such cases now? were the old ones some how altered to implement this?

  • and that's why I don't hear reply, however on approach side much bigger distances are heard in my area) Thank you I did verify that indeed the aircraft that I don't hear read back from receives special departure frequency by tower. Once tower clears aircraft for take off and hands them off to departure controller they use "departure" frequency to read back instructions. It is typically... out in the question for some reason mostly it is "big" aircraft that gets this preferential treatment, but I am not 100% sure why.

  • The FAA offers instrument approach procedures on their website free of charge, and EASA does too. Does Canada have them online for us to use?

  • Watching a video on YouTube of an A340-600 takeoff, I noticed that it has at least two exterior cameras — one for lining up the nosewheel, and the other on the tailfin: After the NTSB recommended the use of exterior cameras in 2012, I'm wondering how widespread these are? Which models of Airbus aircraft have them? Do any Boeings? For bonus points, do these record or are they realtime-only?

  • be mandatory? Are expected altitudes part of lost communications procedures? Am I missing anything with regards to the purpose of expected altitudes? ... for ATC to issue a descend via clearance, though I could be wrong about the second part. Some charts say "VERTICAL NAVIGATION PLANNING INFORMATION" before the expected altitude, so my assumption..., and does this show up in the FMS exactly the same as a mandatory crossing altitude? Are expected altitudes treated as suggestions by pilots or controllers? For example, in the above chart, if you

  • This comes from a flight simulator experiment ages ago in the Boeing 737.... I'm on the runway. I engage the heading switch, followed by the altitude and thrust. The aircraft lifts off, although hardly in a clean rotation. Now I'm wondering: While it did work in the flight simulator, will the autopilot follow these commands in real life as well if I repeated this in a business or commercial jet? Is there anything stopping the autopilot from engaging a specified altitude or from following instructions which are utter nonsense?

  • According to Airbus: ‐ After the flight crew selects reverse thrust, they must perform a full stop landing. Does it really make sense to have this limitation, and why? What happens if you realise there's not enough space to land, and you've still got adequate speed?

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