A passenger jet has collided with a helicopter while landing at Ronald Reagan National Airport near Washington.

    • Hildegarde@lemmy.blahaj.zone
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      22 hours ago

      From information on flightradar24’s article, the collision happened at around 300-400 ft. Those altitudes are too low for TCAS to issue alerts. The Black Hawk had a transponder broadcasting with mode S, so it would be visible to TCAS and the tower, but it was not broadcasting ADS-B, which would let you see it on most flight tracking websites.

      The jet would have received an audible TCAS alert if this happened at a higher altitude.

      • AA5B@lemmy.world
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        19 hours ago

        Not only is it too low for things to work effectively but now you have city lights to contend with. It’s all too possibly the helicopter lost sight of the jet amidst all the lights.

        There must have been a reason why the jet was told to switch runways. Was there another jet that could have been confused for that one? At night it’s tough to see distances and types of jet, so it’s possible the helicopter was looking at the wrong jet.

        The jet was told to switch runways. They adjusted but were they where they were supposed to be? Airports have a complex layout of traffic patterns and controlled airspace. When it works well, traffic is nicely separated and predictable, but when everything changes it’s easy to not be where you’re supposed to be

        • Hildegarde@lemmy.blahaj.zone
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          16 hours ago

          TCAS is a transponder based system. Warnings are suppressed at low altitude by design, and city lights do not interfere with it.

          Runways get changed all the time for many reasons. Every runway at washington national is in a different direction, it would be a different approach entirely and not a last minute change. There is no evidence that the plane flew the approach wrong. There is ADS-B data for the full flight. Anyone can check the plane’s actual flighpath.

          Pilots can refuse ATC orders that are unsafe. The approach they were originally planning would have crossed the river and had the same risk of traffic.

          The helicopter pilot seeing the wrong plane is a likely explanation. There were other planes in the area. The controller warned of the traffic. The pilot confirmed having the plane in sight.

          • AA5B@lemmy.world
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            7 hours ago

            TCAS is … suppressed at low altitude by design,

            Yep so that may not have helped

            and city lights do not interfere with it.

            But they do interfere with what you can see, and they were told to see and avoid

            Every runway at washington national is in a different direction, it would be a different approach entirely and not a last minute change

            Jets head toward their expected pattern from quite a few miles out. Tower changed their runway, so they needed to adjust. You’re right that there’s no indication it was last minute, but it was a change from their plan and change brings risk

            The helicopter pilot seeing the wrong plane is a likely explanation. There were other planes in the area. The controller warned of the traffic. The pilot confirmed having the plane in sight.

            Distance and heading can be difficult to judge, especially in the clutter at low altitude. Maybe they saw a different plane. Maybe they saw a parking lot light

            • Hildegarde@lemmy.blahaj.zone
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              6 hours ago

              The helicopter was flying at 300-400 feet. The buildings to the southeast are shorter than that. Those areas are 3-4 story sparse developments not highrises. The plane was above and descending. It would be seen against the night sky. There would be no buildings near where the helicopter would be looking for the plane.

              Landing approaches are started from specific navaids. This plane was not off course because it was given a different arrival route than expected.

              The airspace around DC is some of the most restricted in the world. Routes into the national airport are very tight with little allowance for error. Most of the routes come in over the river to avoid overflying government buildings, and the involved plane had a sharp left final over the river. The plane may have turned when the helicopter wasn’t expecting it.

              This is all speculation. Investigations into things like this are thorough. It is far to early to assign blame to anyone involved.

    • Absaroka@lemmy.world
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      19 hours ago

      Watching the video, it’s also very weird the helicopter didn’t seem to try and avoid the collision at all.

    • DreamlandLividity@lemmy.world
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      23 hours ago

      I always assumed military aircraft didn’t have TCAS or any other such technology that could give away the position of the aircraft. But thinking about it, why not? They do have transporders, they just have an off switch for them.

      So I don’t know. Maybe they don’t have TCAS, maybe they forgot to turn it on. Either way, TCAS probably wouldn’t work at low altitude during a landing.

      We will probably have to wait for the accident report.

    • feannag@sh.itjust.works
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      23 hours ago

      Navy variants of the Blackhawk do not have TCAS. I can only assume the army is similarly lacking that function.