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Comment by fwipsy | Hacker News Reader

Excerpts from the article:

"(According to investigators, this altitude data was rounded to the nearest 100.)"

[...]

"At over 100 miles an hour, the helicopter could have risen to 300 feet from 200 in seconds, because of winds or other factors. Such anomalies are not unusual and can be quickly corrected."

I read your comment as implying that you've concluded it's pilot error. I don't disagree, but a good system should be robust against human error. Perhaps the permitted flight paths were too close together? I'm not an expert, but a commercial jet making a landing approach 100 feet above a helicopter doesn't seem safe or normal to me.

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100ft isn't anywhere near an acceptable margin. The helicopter may bear the immediate blame due to going above the altitude limit, but ultimately the design of this corridor was completely nuts.

This seems like a classic normalization of deviance. Reportedly there were literally a hundred automated collision warnings between airliners and helicopters in this area over the past decade. One such warning should raise eyebrows. Two should start people thinking there's a systemic problem. More than a handful should prompt an investigation to resolve the root cause of the conflicts. Instead, they (at least the system as a whole) seem to have decided that they weren't a real problem because nothing had happened yet.

In other situations the normal vertical separation is 1000ft. In this situation ATC was depending on the visual conditions for the pilots to "see and avoid", but it's especially nuts if you factor in wind shear and wake turbulence that can change an altitude by 100ft in seconds.

I wonder whether telling either the army to use cars, or that the airport should be moved further away from the city was doable for atc personnel, or even their higher ups.

You wouldn't need anything so extreme. Just prohibiting landings on runway 33 simultaneous with helicopter traffic underneath the approach path would have done wonders here. Additionally, require military traffic to have ADS-B, and ensure that the tower is sufficiently staffed to have the dedicated helicopter controller that it's supposed to have.

Just prohibiting landings on runway 33 simultaneous with helicopter traffic underneath the approach path .. Additionally, require military traffic to have ADS-B

I'm thinking you're not quite understanding the nature of the missions many of these helos undertake.

I personally don't think the practice should be allowed, but that's why we need to have a discussion. We need to determine how necessary are these practices?

That said, I can guarantee you that the ideas you put forth would be rejected by government and military planners. Those ideas would defeat the entire point of some missions. What we can do is talk about whether or not DCA is a facility that should be open? Things of that nature.

But any ideas that result in tipping off the mission will be non-starters for the guys and gals seated on the military/intelligence side of the table.

I don't understand what you mean. What is it about these flights that would make it impossible to prohibit them from flying under the 33 approach while it's in use, or prohibit incoming traffic from landing on 33 while these flights are nearby? Why can't they use ADS-B?

One of the missions of those helicopters was the immediate evacuation of personnel in the event of attack against Washington D.C. That requires the speed and range that a helicopter can provide but cars can't. To do that mission requires training and practice flying through the area, because as everyone in the military knows, you fight like you train, and so they need to be flying through DC regularly, both day and night.

As for DCA itself, yeah, there have been people trying to close it for decades- that was originally the plan once they opened IAD in 1962. But DCA was so close and so convenient to the city and IAD (and later BWI) are so far away that no one has really wanted to pull the trigger on closing it, even as the airspace got more and more complex after the September 11th terrorist attacks.

NTSB did release some follow up data. They have the bottom of the jet at 325', +/- 25'. Helicopters add a tough element to any airport operation and DIA is one of the more challenging airports with the extra restrictions on routing.

(Never flown into that one as not an ATP. I'd never be able to get closer than College Park. Even that was a non-trivial exercise in paperwork.)

What's complicated about it? Don't get within a mile. Some 250g drone can't, why should this thing?

why should this thing?

'Cuz "National Security".

End of discussion.

You may laugh, but that's historically the argument in support of these practices. No one wants to go on record as questioning the practice. Maybe they will finally do something now? But it wouldn't surprise me if they don't.

DCA, not DIA. DIA is in Denver.

> Perhaps the permitted flight paths were too close together?

My understanding is that the helicopter was military and didn't need to submit a flight plan. They get to fly where ever they want

There is a difference between not needing to submit a flight plan, and flying wherever they want. They absolutely have rules to follow about where they fly.

> They get to fly where ever they want

Reminds me of the story of the Navy ship and lighthouse: https://en.wikipedia.org/wiki/Lighthouse_and_naval_vessel_ur...

A flight plan doesn't have much to do with permission to fly somewhere. It's more about ATC not being surprised if an aircraft shows up in a given airspace, and search & rescue noticing if an aircraft doesn't show up at its planned destination.

All aircraft have separation and avoidance rules that apply at all times.

> They get to fly where ever they want

In controlled airspace aircraft fly where they are told to fly by controllers:

* https://en.wikipedia.org/wiki/Controlled_airspace

Well, except for VIP helos. Basically certain military and government aircraft can do things other pilots can't.

I can guarantee you, if I were flying the helo, the transcript between myself and ATC would be significantly different. When you're certain military and government pilots, it's basically, "Um, sir, I don't mean to disturb you, but are you certain you have visual?".

The real issue is allowing certain military and government aircraft to essentially do whatever they like. I understand the whole "National Security" thing, but, I mean, maybe we can at least talk about the practice? It's not a practice that seems unsafe. It's a practice that is unsafe.

I highly doubt this. US Air Force fighters intercepting an unknown aircraft near the Whitehouse still request ATC clearance so they don't accidentally run into an airliner. And we're talking something that shoots missiles into other planes. Any VIP transport isn't going to get any higher priority.

Here's why: https://en.wikipedia.org/wiki/Hughes_Airwest_Flight_706

And they don't need priority. If Air Force One wants to land anywhere, they simply have the airport closed and the airspace cleared. And you don't need to close an entire airport. You can just mark off a place in the sky that's restricted during a certain time.

Additionally, any plane can declare an emergency and take priority over all other traffic, including anything military, including Air Force One. It would be silly if you think you are so important that an airplane currently in the middle of crashing will go around you.

You can verify all of this by listening to ATC transcripts on YouTube. They are pretty easy to find if you're looking for sources.

You're misinformed.

"US Air Force fighters intercepting an unknown aircraft near the Whitehouse" don't request anything from anyone outside their chain of command. That's not how anyone gets orders sir.

NMCC is in charge, and any idea you have to the contrary is yours alone.

Now, will NMCC, or someone in the chain, communicate with ATC as part of the response? Yes. But only for the purposes of keeping ATC apprised of the situation and informing ATC that fighters are in the area. No one is standing around waiting on the results of clearance requests in these scenarios.

Your assertions would not only be bad policy, but they're contrary to military sense.

My idea is to sit down and have the conversation about why certain helos are engaged in some of these dangerous practices? And if that reasoning be sufficiently compelling, to consider the pros and cons of closing DCA. If the reasoning be not compelling, then we need to have another discussion about different operating protocols for these aircraft.

The fighters talk directly to ATC to request to a block of airspace to fly in so they don't run into anything and ATC keeps it clear. This is a regular occurrence in the DC area. This also happens with civilian aircraft like medevac helicopters. They obviously need priority but you also need to route them around stuff you can't move out of the way in time.

You may not strictly need the clearance but it's a really good idea to know where it's safe to fly.

> My idea is to sit down and have the conversation about why certain helos are engaged in some of these dangerous practices?

This isn't different from planes colliding on a runway. There are bad procedures. The NTSB will investigate and make recommendations. The military will offer their opinions. And the FAA will ignore everything until it happens a couple more times. Or with see and avoid, bury their heads in the sand and hope the problem goes away.

And except for planes that don't or can't follow rules or instructions. For example: https://en.wikipedia.org/wiki/2006_New_York_City_Cirrus_SR20...

I'm sure in a national defense scenario they have ways to "pull rank" and do what they need to do. But this would require a good reason. Like a VIP was on board and someone was attacking them.

It's very easy to pull rank. When Air Force One flies into an airport they have the airport and airspace closed.

There's also no need to because current procedures already covers this. All the aircraft would have to do is declare an emergency and they get to go and land wherever they want.

In that scenario civilian aircraft are all grounded.

This is the thing people don't understand. Certain military and government aircraft can pull this kind of crap even when it doesn't seem necessary. (At least not to me as an outsider).

Now it's easy to say, "Well, Bilbo0s, who are you to say it wasn't necessary?"

That's true, but it's an argument that's closed onto itself. We can't probe any further 'cuz "National Security". So this unimaginably dangerous practice of allowing military and government pilots to do this sort of thing "if necessary" continues.

We need to, at minimum, have a discussion about why the practice is necessary?

Your understanding is incorrect, this isn't how airspace works.

Anyone flying under visual flight rules does not need to submit a flight plan. If you never enter controlled airspace, you don't have to talk to ATC at all.

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