bilby
Fair dinkum thinkum
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It's incredibly easy to imagine.I'm not a military helicopter pilot, but if there are three people in a military helicopter and even if the pilot is watching the ground due to flying low, wouldn't someone else have noticed the beacons and massive flood light of the oncoming plane? They are right next to Reagan, about to intersect the landing path, so if there was a time to be extra vigilant, this would be the time. It is possible someone at ground control made a terrible mistake, but it just seems hard to imagine the helicopter made no notice of the plane.
The entire structure of ATC in the area is deeply flawed, as it allows visual separation of aircraft at night in an urban environment. Washington DC is far from the only US city that has this problem; It is endemic in US ATC.
A few things to note:
1: An aircraft that is on a collision course with you appears stationary against the background; It grows larger as a collision nears, but this effect is hard to discern even in daylight until it is too late to respond.
2: A stationary light (or set of lights) against a background of lights (such as a city) is very hard to spot at all.
3: Even if you see another aircraft in these conditions, it is close to impossible to identify its type at night. The ATCO asks the Blackhawk pilot if he has visual "on the CRJ"; The helicopter pilot responds that he does. However, he cannot know that (and appears in this case to have been tragically mistaken). He likely had visual on the next aircraft in traffic descending into KDCA, and not on the aircraft with which he collided. There was a string of aircraft on approach to runway 1 at the time; The CRJ he collided with had made a dogleg to approach runway 33.
The CRJ pilots did everything exactly by the book.
The ATCO did everything exactly by the book.
The Blackhawk pilots did everything exactly by the book.
The problem is that what is in the book was an accident waiting to happen. Relying on pilots to correctly visually identify air traffic in a busy airspace at night over a cityscape will inevitably result in a crash, sooner or later.
Visual separation in good weather (even at night) is SOP in US Category B airspace (the most strictly controlled category, and the category in which this crash occurred). It is prohibited in Europe, where separation in Cat B airspace is always the responsibility of ATC, and cannot be handed off to pilots to be managed visually.
The Blackhawk pilot believed that he had the conflicting traffic in sight, and that he was able to pass behind it as instructed. The ATCO believed that too. But these people had two different aircraft in mind; And at night, there is no good way to check - in daylight, the helicopter pilot asked to confirm visual on "the CRJ" might have thought "that's not a CRJ, it's an A319 - Oh, shit, there must be another conflicting aircraft to look out for!". At night, he can see lights moving against the background, and has no clue that there is another set of lights not moving against the background, that he desparately needs to be identifying and avoiding.
As with all crashes, there are a lot of factors that conspired to lead to disaster here. But central to it all is the way the system is intended to work, which requires the impossible - visual separation at night in busy airspace.
The US got away with it for sixteen years.
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