Plane Crash In DC

[Skeptical Greg]

Sean Duffy, former TV reality show star, now Minister of Transportation, IIRC now confirms initial investigation seems to show the helicopter was at the mandated 200m height.

ATC error?

Initial investigation by whom?

The helicopter had confirmed twice that it had visual on the aircraft, so I don't think it's a stretch to find some fault with ATC for not being more proactive regarding the helicopter, i.e., questioning their visual, however, we are talking about seconds at this point.
With hindsight, earlier action to divert the chopper was clearly called for.

 

[JayUtah]

Sean Duffy, former TV reality show star, now Minister of Transportation, IIRC now confirms initial investigation seems to show the helicopter was at the mandated 200m height.

You did not provide a citation for this claim. When was this claim made? In what context?

Senior Investigator in Charge (IIC) Bryce Banning reported on Feb. 1, in the video of a press conference posted to the NTSB's official YouTube channel, that the recorder from the helicopter had not yet been downloaded and was in the process of drying out. It was expected to be downloaded Feb. 2, but this has not yet been reported by the NTSB. The DFDR and CVR from the airliner have been recovered, dried out, downloaded, and its data integrated/reconciled with the ADS-B data. On this basis the NTSB is able to issue a preliminary finding that the collision occurred at 325 ft ± 25 ft (corrected MSL) measured to the bottom of the CRJ fuselage. Currently the NTSB's position is that the indication of altitude at the moment of a collision is necessarily the altitude of both aircraft. However, as of Feb. 1 the NTSB did not have onboard data from the helicopter and therefore cannot say whether all the pertinent data agrees.

The CVR record suggests that the airliner crew saw the helicopter. The DFDR indicates a commanded pitch-up maneuver at the time of impact.

According to Banning, the altitude reported for the helicopter in the radar recording was 200 feet. However, Banning cautions that this is not high-fidelity data and should not be relied upon to establish the altitude of the helicopter. The data recorder from the helicopter is considered the affirmative data. There are various radar data reconstructions from consumer sources that apparently show the helicopter climbing above 200 ft at the time of collision. The NTSB does not consider this to be reliable information and cautions against speculation based on it.

Banning reports that the helicopter was within the lateral boundaries of the designated helicopter route. He reports that "the ceiling of that route was 200 feet." He did not elaborate on the issue of whether that was considered a mandatory or a recommended ceiling.

In the preliminary remarks at that same press conference, NTSB member Inman pointed out that 200 feet (i.e., the ceiling of the helicopter route and the nominal approach altitude to DCA runway 33) is not considered a safe vertical separation. 1000 feet—the separation you learn in flight school—is still considered the minimum safe vertical separation even for approaches. This is likely why the the controller instructed the helicopter to pass behind the airliner.

ATC error?

In what way do you think ATC was in error?

 

[JayUtah]

The helicopter had confirmed twice that it had visual on the aircraft, so I don't think it's a stretch to find some fault with ATC for not being more proactive regarding the helicopter, i.e., questioning their visual...

Indeed the request for and granting of permission for visual separation places primary responsibility for collision avoidance on the pilot. The controller initially granted permission. When the radar data indicated the possibility for a collision, the controller confirmed with the helicopter pilot that the basis for visual separation still existed.

The NTSB reports that radar indications in this scenario may lag by as much as 4 or 5 seconds. This is obviously not sufficient granularity to allow a controller fine-grained control for distances of only a few hundred feet or a few seconds. This is why controllers will sometimes cede responsibility for traffic avoidance to the pilots who can ostensibly see the aircraft in real time. The NTSB cautions that it is still working on the ATC data and cannot offer any opinion regarding ATC actions. However, nothing I've seen so far suggests that ATC committed any error. There may be something to say about understaffing. But as it stands, the actions of the controller seem consistent with established practice.

 

[Dr.Sid]

Yeah, in hindsight, controller should have instructed the helo to evade to the east, instead of asking if he has the visual. There must be some rules regarding the visual separation. And if they were adhered to, they should be tightened. For example if you get collision warning, order evasion, don't ask for anything.
Also good point with the altitude, 200 ft is indeed nothing. For all ATC purposes the helo and the plane were on the same level from the beginning.

 

[jt512]

The NTSB reports that radar indications in this scenario may lag by as much as 4 or 5 seconds. This is obviously not sufficient granularity to allow a controller fine-grained control for distances of only a few hundred feet or a few seconds. This is why controllers will sometimes cede responsibility for traffic avoidance to the pilots who can ostensibly see the aircraft in real time.

My understanding has alway been that the main reason for visual separation in Class B airspace was to waive the minimum separation requirements thus allowing more traffic to operate in the airspace, more frequent landings and departures, etc.

 

[JayUtah]

Yeah, in hindsight, controller should have instructed the helo to evade to the east, instead of asking if he has the visual.

That would have entailed the helo going outside the lateral limits of the route, which brings up other issues. As long as the helo is in the route, other traffic knows to look for low-flying aircraft there. Keep in mind the helo can also descend or hover.

There must be some rules regarding the visual separation. And if they were adhered to, they should be tightened. For example if you get collision warning, order evasion, don't ask for anything.

The rules are pretty simple: listen to ATC, actually get eyes on what ATC is telling you is out there, and don't hit it. ATC has the responsibility to advise one or both pilots if the aircraft flight paths seem to merge. This was done. Based on what we know now, and accepting the hypothesis that the helo pilot mistook a trailing airplane for the one he was supposed to stay separate from, I would imaging that the approvals for visual separation may include additional requirements for "report traffic in sight," such as confirming range, distance, and relative bearing.

I haven't seen an NTSB briefing posted for today. During briefing 3, there was some comment on a TCAS voice warning that is heard on the CVR of the airliner. TCAS will not issue a resolution advisory below 1000 feet, but it will issue a "traffic, traffic" voice warning when it detects a potential collision.

Also good point with the altitude, 200 ft is indeed nothing. For all ATC purposes the helo and the plane were on the same level from the beginning.

If I were flying any sort of an aircraft and missed an airliner by only 200 feet vertical separation, I would be puckering as hard as it's possible to pucker.

 

[Vixen]

You did not provide a citation for this claim. When was this claim made? In what context?

Senior Investigator in Charge (IIC) Bryce Banning reported on Feb. 1, in the video of a press conference posted to the NTSB's official YouTube channel, that the recorder from the helicopter had not yet been downloaded and was in the process of drying out. It was expected to be downloaded Feb. 2, but this has not yet been reported by the NTSB. The DFDR and CVR from the airliner have been recovered, dried out, downloaded, and its data integrated/reconciled with the ADS-B data. On this basis the NTSB is able to issue a preliminary finding that the collision occurred at 325 ft ± 25 ft (corrected MSL) measured to the bottom of the CRJ fuselage. Currently the NTSB's position is that the indication of altitude at the moment of a collision is necessarily the altitude of both aircraft. However, as of Feb. 1 the NTSB did not have onboard data from the helicopter and therefore cannot say whether all the pertinent data agrees.

The CVR record suggests that the airliner crew saw the helicopter. The DFDR indicates a commanded pitch-up maneuver at the time of impact.

According to Banning, the altitude reported for the helicopter in the radar recording was 200 feet. However, Banning cautions that this is not high-fidelity data and should not be relied upon to establish the altitude of the helicopter. The data recorder from the helicopter is considered the affirmative data. There are various radar data reconstructions from consumer sources that apparently show the helicopter climbing above 200 ft at the time of collision. The NTSB does not consider this to be reliable information and cautions against speculation based on it.

Banning reports that the helicopter was within the lateral boundaries of the designated helicopter route. He reports that "the ceiling of that route was 200 feet." He did not elaborate on the issue of whether that was considered a mandatory or a recommended ceiling.

In the preliminary remarks at that same press conference, NTSB member Inman pointed out that 200 feet (i.e., the ceiling of the helicopter route and the nominal approach altitude to DCA runway 33) is not considered a safe vertical separation. 1000 feet—the separation you learn in flight school—is still considered the minimum safe vertical separation even for approaches. This is likely why the the controller instructed the helicopter to pass behind the airliner.


In what way do you think ATC was in error?

I can't find the relevant tweet ATM but this one is similar. It's seems to be as you say.

https://twitter.com/x/status/1886060370113986572

As for the ATC, it seems the plane was diverted at very short notice to runway33 but let's see what the investigation says. Initial unconfirmed claims say there was another plane ahead of the other one and it is this that the pilots said they had in sight. They had night vision goggles so their peripheral vision isn't going to be good if there was another unexpected plane coming in from their right. As to why the helicopter suddenly seemed to ascend to 325ft plus or minus 25 ft, maybe it was a last few seconds attempt to avert a collision.


.

 

[Vixen]

That would have entailed the helo going outside the lateral limits of the route, which brings up other issues. As long as the helo is in the route, other traffic knows to look for low-flying aircraft there. Keep in mind the helo can also descend or hover.


The rules are pretty simple: listen to ATC, actually get eyes on what ATC is telling you is out there, and don't hit it. ATC has the responsibility to advise one or both pilots if the aircraft flight paths seem to merge. This was done. Based on what we know now, and accepting the hypothesis that the helo pilot mistook a trailing airplane for the one he was supposed to stay separate from, I would imaging that the approvals for visual separation may include additional requirements for "report traffic in sight," such as confirming range, distance, and relative bearing.

I haven't seen an NTSB briefing posted for today. During briefing 3, there was some comment on a TCAS voice warning that is heard on the CVR of the airliner. TCAS will not issue a resolution advisory below 1000 feet, but it will issue a "traffic, traffic" voice warning when it detects a potential collision.


If I were flying any sort of an aircraft and missed an airliner by only 200 feet vertical separation, I would be puckering as hard as it's possible to pucker.

...and the smell would be terrible,


.

 

[Dr.Sid]

That would have entailed the helo going outside the lateral limits of the route, which brings up other issues. As long as the helo is in the route, other traffic knows to look for low-flying aircraft there. Keep in mind the helo can also descend or hover.

Yes, but the helo was moving fast, based on videos. 50kts at least. Helos can stop, but not fast, especially the big ones. But even the big ones can do sharp turn. So at the moment of collision alert I think it was too late to stop. At the moment of the first visual separation request probably not.

 

[JayUtah]

As for the ATC, it seems the plane was diverted at very short notice to runway33 but let's see what the investigation says.

The diversion has been confirmed. Pilots familiar with the airport report that this is very common. It does, however, require flying an atypical approach.

Initial unconfirmed claims say there was another plane ahead of the other one and it is this that the pilots said they had in sight.

I'm not sure which planes you mean by "another plane" and "the other one." There has been considerable speculation that the helicopter pilot misidentified the traffic he was supposed to avoid, but no findings as yet.

They had night vision goggles so their peripheral vision isn't going to be good if there was another unexpected plane coming in from their right.

The NTSB has not yet determined whether the helicopter pilots were wearing the night vision goggles that were indicated for this kind of flight. However it is reasonable to suppose that in the case where the goggles were worn, peripheral vision might be affected. Part of the investigation will typically include reconstructing sight lines based on a fully reconciled data record.

As to why the helicopter suddenly seemed to ascend to 325ft plus or minus 25 ft, maybe it was a last few seconds attempt to avert a collision.

I'm not sure why a pilot would ascend to avoid traffic that he would have ostensibly observed to be above him.

 

[JayUtah]

Yes, but the helo was moving fast, based on videos. 50kts at least. Helos can stop, but not fast, especially the big ones. But even the big ones can do sharp turn. So at the moment of collision alert I think it was too late to stop. At the moment of the first visual separation request probably not.

Yes, I realize that. My point is simply that when directing fixed-wing aircraft, a controller must work within basic aerodynamic principles. An aircraft must continue moving forward at sufficient airspeed to maintain the lift required to accomplish the desired flight path. If necessary, a helicopter has the option to hover, given sufficient stopping time. It can also fly low more safely than a fixed-wing airplane. These aren't solutions for collision avoidance at the last second so much as options for a controller to consider.

The Blackhawk pilots who have commented on this agree that it is a highly maneuverable aircraft and that the instinctive reaction from the pilot will include a sharp turn.

 

[arthwollipot]

Based on the early evidence, the plane crash appears to have been primarily caused by the helicopter having the wrong traffic in sight. Contributing factors are likely to include the helicopter exceeding the recommended maximum altitude for the route segment, the tower controller failing to clearly explain the location of the traffic on his second call, the heavy volume of traffic at the airport, understaffing of the tower, the policy of allowing helicopter traffic to cross the final approach path of runway 33, and permitting exceptions to standard separation criteria when pilots request visual separation.

Thank you for your explanation of the curcumstances surrounding the crash but with all due respect I didn't ask you that.

I asked whether you believe that DEI caused, or was a contributing factor, in the crash.

 

[jt512]

Thank you for your explanation of the curcumstances surrounding the crash but with all due respect I didn't ask you that.

I asked whether you believe that DEI caused, or was a contributing factor, in the crash.

Check your reading comprehension.

 

[Skeptical Greg]

Here is a time-line account.

A visual timeline of the collision between a passenger plane and a Black Hawk helicopter in DC​

There is audio between ATC and both aircraft.

There is an interesting map projection of the chopper's flight path prior to the collision. There was a lot of deviation from the prescribed route and altitude. Of course, that may have been typical for a training mission of this type, and non consequential in the absence of a collision.

 

[arthwollipot]

Check your reading comprehension.

I've read it a bunch of times. Nowhere in your post do you say whether you think DEI caused or contributed to the cause of the crash. In fact you appear to be going out of your way to avoid saying whether you think or do not think that. I am given to wonder why.

Let me dig a little deeper. You say that the helicopter exceeded its maximum altitude. Was DEI responsible or partly responsible for that? You say that the tower controller failed to clearly explain the location of traffic. Was DEI responsible or partly responsible for that?

Was understaffing because of DEI? Was the policy of allowing helicopters to cross the approach path or the exceptions to standard separation criteria because of DEI?

These are easy questions to answer, and a simple yes or no answer to all of them at once will satisfy me.

 

[Trebuchet]

Another good video by Juan Browne.

 

[Skeptical Greg]

The NTSB has not yet determined whether the helicopter pilots were wearing the night vision goggles that were indicated for this kind of flight.

Senator Tammy Duckworth, a Blackhawk pilot says:

My understanding is that they were not using NVGs," Duckworth replied. She said that in an area where there are a lot of lights, they're "not as useful a tool," and are really more suited to "a combat situation in the dark." Around the airport, "with that much ambient light, they were on visual flight rules, and they were operating well within the parameters for which they have been trained, and the aircraft was designed to operate in.

NVG's don't seem like a good idea to me when there are things like aircraft landing lights going on around you.

 

[jt512]

I've read it a bunch of times. Nowhere in your post do you say whether you think DEI caused or contributed to the cause of the crash.

I listed what I think the primary cause was and the contributing factors. There are an infinite number of things I didn't list as contributing factors. A 6-year-old would understand why.

In fact you appear to be going out of your way to avoid saying whether you think or do not think that. I am given to wonder why.

Maybe it has something to do with your condescension.

Let me dig a little deeper. You say that the helicopter exceeded its maximum altitude.

Nope. Check your reading comprehension.

You say that the tower controller failed to clearly explain the location of traffic. Was DEI responsible or partly responsible for that?

How would I (or anyone, for that matter) even know that?

Was understaffing because of DEI? Was the policy of allowing helicopters to cross the approach path or the exceptions to standard separation criteria because of DEI?

It has been been credibly alleged that ATC is still suffering staffing shortages as the result of an Obama-era program to increase the number of minority air traffic controllers. I don't know whether that it true or not.

 

[JayUtah]

Senator Tammy Duckworth, a Blackhawk pilot says:

I trust Sen. Duckworth. She has provided valuable insight.

NVG's don't seem like a good idea to me when there are things like aircraft landing lights going on around you.

My intuition agrees. The principal night-vision equipment I've personally used is made for ground combat.

The issue is that according to the NTSB, NVGs are recommended for this mission profile. But practical experience such as that of Sen. Duckworth suggests they may not have been worn at this time. This is why it becomes very important to recover equipment from the helicopter in order to see what actually was the case in this accident. And yes, it is possibly gruesome because you may need to carefully inspect the helmet and human remains. With luck, you can recover the bags the equipment is kept in; if the goggles are still in the bag you don't need to go any further.

 

[arthwollipot]

How would I (or anyone, for that matter) even know that?

Well then, do you think as I do that Trump blaming DEI for the crash is breathtakingly stupid?