DC jet helo collision

[tater]

17 minutes ago, K^2 said:

I'm not sure it was reasonable to expect that helo had a fix on the correct plane. And if they believed that they were given a fix on a plane ahead of AA5342, then they were flying exactly as vectored. In other words, they proceeded on the course they had in their plans which would bring them directly under the landing airliner, well within the wash.

My point is they were at the wrong altitude. Look at the instruments, go, "Oh, ****" and drop ~100-150 feet pronto. 200 was the max allowed altitude, this was not somethign they wait to hear from ATC about, they should have never exceeded 200ft unless they asked ATC first those corridors are on the charts, they fly this all the time.  Arguably they should have been closer to 150' to be safe. That alone makes it their fault, the pilot was not looking at the instruments. And yeah, that vertical separation gives them serious problems from the CRJ's wake turbulence. Sucks to be them, but at worst we're talking about 3 deaths in that case—and to the people in the aircraft at fault.

Edited February 3 by tater

[darthgently]

Now I’m hearing that the helo was a crew chief short and they normally have two and they take stations on port and starboard and keep eyes on those sides to assist the pilot.  So maybe they had no eyes dedicated to the left side and having trained with having eyes there the pilot could have ended up with a habitual false sense of security not appropriate to the situation

[tater]

8 minutes ago, darthgently said:

Now I’m hearing that the helo was a crew chief short and they normally have two and they take stations on port and starboard and keep eyes on those sides to assist the pilot.  So maybe they had no eyes dedicated to the left side and having trained with having eyes there the pilot could have ended up with a habitual false sense of security not appropriate to the situation

Those eyes might have noticed the problem caused by their pilot flying way too high, true. Someone needed to be looking at the instruments.

There's clearly Swiss cheese here that could have had holes filled in and prevented the accident by allowing others to correct for the failure of the Blackhawk pilot, but I'm pretty sure that altitude issue will be the primary cause. It's important to come up with systems than can deal with negligence/error, so in this case maybe it's not allowing these helicopter routes any more that are that close to DCR final.

Edited February 3 by tater

[darthgently]

1 hour ago, tater said:

Those eyes might have noticed the problem caused by their pilot flying way too high, true. Someone needed to be looking at the instruments.

There's clearly Swiss cheese here that could have had holes filled in and prevented the accident by allowing others to correct for the failure of the Blackhawk pilot, but I'm pretty sure that altitude issue will be the primary cause. It's important to come up with systems than can deal with negligence/error, so in this case maybe it's not allowing these helicopter routes any more that are that close to DCR final.

Looking at the vids, and estimating the size of the helo and its apparent height above the water it actually looks closer to 200’ than 325’ to me.  Not rigorous, of course.  But this combined with the qualifications the NTSB put on the altitudes, the error bars, and the incongruous ATC altitude for the jet gives me hesitation to assume the altitude of collision.   Especially with the NTSB’s emphasis that they are still evaluating the meaning of all the altitude data.  I could have misunderstood that the 325’+-25’ reading was still possibly in question.  But it doesn’t look 325’ high on collision to me so I’m leaving it open for now

Edited February 3 by darthgently
Fixed 300 to 325

[K^2]

23 minutes ago, tater said:

My point is they were at the wrong altitude. Look at the instruments, go, "Oh, ****" and drop ~100-150 feet pronto. 200 was the max allowed altitude, this was not somethign they wait to hear from ATC about, they should have never exceeded 200ft unless they asked ATC first those corridors are on the charts, they fly this all the time.  Arguably they should have been closer to 150' to be safe. That alone makes it their fault, the pilot was not looking at the instruments. And yeah, that vertical separation gives them serious problems from the CRJ's wake turbulence. Sucks to be them, but at worst we're talking about 3 deaths in that case—and to the people in the aircraft at fault.

And if the ATC gave them clean separation, they could have gone to 500' without endangering anyone. And in fact, if helo crew went to 500', everyone would be safe, including helo crew. Whereas if helo crew stuck to assigned altitude, they might have still died.

There was an error that resulted in more fatalities than there could have been in this particular incident and might not have mattered at all in another, namely exceeding the altitude, and there was an error that absolutely should never have been allowed in any air space ever and would always result in a dangerous situation - namely the overlapping of the paths.

I understand that in this case, by pure chance, the helo exceeding altitude happened to be a deadlier of the two. And I understand the natural instinct to assign blame based on that.

But the reality is that allowing the aircraft close together is the more egregious error. That one could have happened to two heavies and we'd be talking about hundreds dead. That is a more serious error. And we do not know if helo crew, ATC, or airport administration are responsible for this.

 

23 minutes ago, tater said:

Arguably they should have been closer to 150' to be safe.

That part's completely silly. Any limit must have safety margins already built in. If they "should have been closer to 150'," then the limit should have been 150'. It wasn't. It was 200', because it was expected that 200' is safe - and that includes margins of typically about 100' on each side, meaning safe separation distance plus 200' extra for safety, which simply did not exist on this particular intersection. The 200' ceiling was not to provide separation with traffic landing on 33. It was never meant for that.

[darthgently]

I just remembered another reason I’m hesitant to trust the 325’ jet altitude fully.  The first vid I watched was of an ATC screen that showed the converging craft with 3 digit altitude data next to each.  The helo showed a consistent 020 indicating something close to 200’ while the CRJ glyph numbers showed 040 decreasing to 020 at time of impact.  This is all presumably from the ATC CAB and I think radar based which apparently doesn’t resolve well at lower altitudes.   So something clearly isn’t meshing with the barometer or FDR in CRJ compared to the ATC ground radar.  And this gives me pause about conclusions

26 minutes ago, K^2 said:

But the reality is that allowing the aircraft close together is the more egregious error.

This I agree with.  Especially since it is apparently well known in the tower that the ATC radar altitude readings for those very low altitudes are sketchy it would make great sense to expand the horizontal separation as a buffer

[tater]

24 minutes ago, K^2 said:

That part's completely silly. Any limit must have safety margins already built in. If they "should have been closer to 150'," then the limit should have been 150'. It wasn't. It was 200', because it was expected that 200' is safe - and that includes margins of typically about 100' on each side, meaning safe separation distance plus 200' extra for safety, which simply did not exist on this particular intersection. The 200' ceiling was not to provide separation with traffic landing on 33. It was never meant for that.

It should be meant for that, or the route changed. Nonetheless, they were required to fly at or below 200' (bumps up to 300' several miles south) along that route (which was their flightplan, as I understand it). Better ATC might have vectored them out of the way in numerous ways, but they didn't. I have to wonder about the fidelity of their radar when not fed data from the aircraft. Did they even know where PAT25 was?

 

25 minutes ago, K^2 said:

And if the ATC gave them clean separation, they could have gone to 500' without endangering anyone. And in fact, if helo crew went to 500', everyone would be safe, including helo crew. Whereas if helo crew stuck to assigned altitude, they might have still died.

ATC in this case might not have even know where they were as far as I can tell. At least altitude wise. We have to wait for NTSB. The CRJ had ADSB, I don't think the helo did. So their ATC radar might be crap.

 

27 minutes ago, K^2 said:

But the reality is that allowing the aircraft close together is the more egregious error. That one could have happened to two heavies and we'd be talking about hundreds dead. That is a more serious error. And we do not know if helo crew, ATC, or airport administration are responsible for this.

I doubt they'd have crossing aircraft that low, seems far-fetched.

I agree that ATC needs to know where every aircraft is, but the proximal cause of a collision (vs a possible helo down alone) was the helicopter being someplace they were explicitly disallowed (>200').

10 minutes ago, darthgently said:

I just remembered another reason I’m hesitant to trust the 325’ jet altitude fully.  The first vid I watched was of an ATC screen that showed the converging craft with 3 digit altitude data next to each.  The helo showed a consistent 020 indicating something close to 200’ while the CRJ glyph numbers showed 040 decreasing to 020 at time of impact.  This is all presumably from the ATC CAB and I think radar based which apparently doesn’t resolve well at lower altitudes.   So something clearly isn’t meshing with the barometer or FDR in CRJ compared to the ATC ground radar.  And this gives me pause about conclusions

Someone posted or put in a vid a chart of the glideslope, and the tracking data shows the CRJ following it. Manley, maybe?

[tater]

 

[darthgently]

34 minutes ago, tater said:

 

I was certainly misremembering the 3 digit altitude read outs.  PAT25 definitely rises up to meet the jet in the last few seconds going by ATC radar, if that is where the 3 digit code in this vid originates.  I also misremembered the encoding of the 3 digit code as the hundreds being in the 2nd place.

I think I may have suffered a memory bias that our military couldn’t possibly change altitude by 100’, above the ceiling, straight into a jet.  In an extremely high caution area they’d flown in before.  I’m still having trouble wrapping my mind around this.