Houston: Robinson R44 helo down

FlightmechH3

FlightmechH3

Pre-takeoff checklist
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FlightmechH3
Looks like it hit a radio tower
 

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How does this happen? The tower is lit.

 
DJTorrente said:
How does this happen? The tower is lit.
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Per the video, at least one light does seem to be active, but I see no others. That tower was just over 1000’ tall, so it should normally have plenty of lights, but I’m not sure how much or little of it we’re seeing in that video.

However, it turns out there was a NOTAM that the obstruction lights on that tower were inop since 10/17:

10/073 - OBST TOWER LGT (ASR 1052552) 294527.00N0952020.00W (7.4NM NNW HOU) 1033.8FT (999.0FT AGL) U/S. 17 OCT 04:44 2024 UNTIL 31 OCT 23:59 2024. CREATED: 17 OCT 04:44 2024
 
Generally, tower lights are two separate circuits, preferably from separate sources.

The beacon at the top seems to have been working in a normal manner.

The side lights were not on, and that is the NOTAM issue.

They hit the tower not much below the top beacon, two flashes clearly seen before the crash and fireball. Those flashes should have been easily seen from any distance, as they are 500 watts. Flying directly under a flashing light is strange. They thought it was a UFO way high?
 
DJTorrente said:
How does this happen? The tower is lit.
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Not all of the lights were lit--only the beacon at the top. They're flying in an urban area that is saturated with lights. Picking out a lone flashing light that might be blending in with lights on the horizon until you're right on top of it might be a challenge.

The bigger question in my mind is why they were flying that low. They were in the Houston Hobby surface Class B, so I wonder what instructions or guidance they had (or lacked) from ATC.

I don't know how helicopter flying works. Is it one of those things where there are the regs, and then there's reality, such that helicopter flying is a little different from fixed wing flying in a similar way to how Alaska flying is different from CONUS flying?
 
geezer said:
Generally, tower lights are two separate circuits, preferably from separate sources.
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I believe you're thinking of the older-style red lights -- flashing red at the top (AOL) and solid red side lights. This tower used strobes, which are on the same circuit. I'm a (mostly-retired now) broadcast engineer, and we shifted a bunch of towers to strobes to avoid the expense of painting the tower. The FAA and FCC will also permit you flash ALL lights nowadays, even with the older-style red lighting. We do it on WDJC FM in Birmingham. (Confused a lot of my fellow engineers when they saw it, too. "You done wired your lights wrong!") :)

FWIW, if I had to guess, the helicopter clipped the guy wires as it closely approached the tower. You can see the fireball move a bit before the tower starts falling. Basically, it was a giant spinning wire cutter. The helicopter immediately disintegrated (thus the fireball), then the tower started falling.

Most of the stress on a tower is "straight down" ... it has to support its own weight plus attachments (i.e., antennas). The guys are there to keep the tower from bending ("kinking"). Once a tower starts to kink, even modestly, that tower is coming down.

I lost some friends in Huntsville several years ago when a winch line snagged and bent one of the sections. The tower fell, and in the process, picked up the winch and threw it (and the winch operator) over a hundred feet.

What happened here is tragic. This was one of my personal nightmares when I was active in the field, too. It's not easy keeping strobes in service on a 1,000' lightning rod. (Ask me how I know.) We religiously called in NOTAMS (within 15 minutes, under the rules) anytime our lights were out, and then prayed that pilots would notice them among all the other jabber and garbage in the NOTAM lists. I remember thinking, "this is the 21st century -- you'd think they could sort NOTAMs by priority somehow ..."
 
This flight path or similar was repeated very often, including several times prior on the night of the accident, and a dozen times during the week prior. A big loop from Ellington up to Pasadena, then following the Buffalo Bayou to Downtown, then south toward NRG and back to Ellington. This, along with the presence of a child, leads me to believe this is a sightseeing operation.

Every time they passed the KQUE tower previously, they gave it a 1000’ berth, sometimes north, sometimes south. Except this time, where they flew right into it.

As they were flying toward the north edge of downtown, I expect their forward visual would have been full of lights. Will be interesting to hear whether they had an operating and non-inhibited HTAWS.
 
Jim_R said:
only the beacon at the top.
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It kind of looks like it might be the top beacon, but at their presumed altitude of 600’, they would have been only a bit more than halfway up the tower. From that camera angle and looking at the horizon, it doesn’t look like that beacon is situated anywhere near another horizon-to-helicopter length above the helicopter’s impact point. One of three possibilities exists: that’s not the top light, the camera angle is deceptive, or the reported ADS-B altitude was off.
 
The altimeter was 30.24, so that could account for a 300’ discrepancy with the ADS-B. That would put the helo much closer to the top at the point of impact.
 
Stephen Poole said:
What happened here is tragic. This was one of my personal nightmares when I was active in the field, too. It's not easy keeping strobes in service on a 1,000' lightning rod. (Ask me how I know.) We religiously called in NOTAMS (within 15 minutes, under the rules) anytime our lights were out, and then prayed that pilots would notice them among all the other jabber and garbage in the NOTAM lists. I remember thinking, "this is the 21st century -- you'd think they could sort NOTAMs by priority somehow ..."
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Stupid question, but is there a FAA suggestion box?
 
Flying Keys said:
This flight path or similar was repeated very often, including several times prior on the night of the accident, and a dozen times during the week prior. A big loop from Ellington up to Pasadena, then following the Buffalo Bayou to Downtown, then south toward NRG and back to Ellington. This, along with the presence of a child, leads me to believe this is a sightseeing operation.

Every time they passed the KQUE tower previously, they gave it a 1000’ berth, sometimes north, sometimes south. Except this time, where they flew right into it.

As they were flying toward the north edge of downtown, I expect their forward visual would have been full of lights. Will be interesting to hear whether they had an operating and non-inhibited HTAWS.
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Additional detail on prior flights on 10/20:

On the 1714 CDT flight, the track approaching the antenna was entirely south of Navigation Blvd, keeping the helo well clear of the antenna.
On the 1847 CDT flight, the track approaching the antenna crossed Navigation Blvd at Engelke and then crossed Engelke at Palmer, about one block from the antenna.
On the 1942 CDT accident flight, the approach to the area of the struck antenna was entirely to the north of Navigation Blvd.
 
AquaLand said:
Additional detail on prior flights on 10/20:

On the 1714 CDT flight, the track approaching the antenna was entirely south of Navigation Blvd, keeping the helo well clear of the antenna.
On the 1847 CDT flight, the track approaching the antenna crossed Navigation Blvd at Engelke and then crossed Engelke at Palmer, about one block from the antenna.
On the 1942 CDT accident flight, the approach to the area of the struck antenna was entirely to the north of Navigation Blvd.
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Yes. And a flight late Saturday (technically Sunday AM UTC) went north of the tower, avoiding it by about the same distance as the other (successful) flights.
 
Flying Keys said:
Will be interesting to hear whether they had an operating and non-inhibited HTAWS.
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I hope I didn't sound like I was blaming anyone involved -- more just exasperated. I also wondered about obstacle and terrain avoidance on-board.

I remember the relief I felt several years back when a sightseeing JetRanger lost engine power over the Hudson and made a forced landing... on emergency airbag floats designed and attached to the skids just for that purpose. Not long after Cactus 1492, I remember thinking that this was how these things were supposed to work out -- At the end of the day everyone who got on board got to go home. This time, not so much.
 
In a different video shown on KPRC, two tower lights can clearly be seen, one mid-height and the other near the top. As the accident helicopter approaches, you can see the beam of the landing light begin to illuminate the tower. As the distance closes, the light beam walks up the tower and shrinks in diameter. At impact, the light beam is small and bright, giving the appearance that the accident helicopter struck the tower dead center.
 
AquaLand said:
In a different video shown on KPRC, two tower lights can clearly be seen, one mid-height and the other near the top. As the accident helicopter approaches, you can see the beam of the landing light begin to illuminate the tower. As the distance closes, the light beam walks up the tower and shrinks in diameter. At impact, the light beam is small and bright, giving the appearance that the accident helicopter struck the tower dead center.
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Thanks, I hadn't seen that one yet. Here's a link to the page with that video: https://www.click2houston.com/news/...ct-of-houston-helicopter-crash-that-killed-4/
 
Not much in the audio, but sounds like they were intentionally staying at 600 feet.

 
mark.staggs said:
Not much in the audio, but sounds like they were intentionally staying at 600 feet.

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Ok, so that precludes the ADS-B error. I still hold that the light we saw in the original black and white video is not the top light. With the new video, there’s at least one even lower showing. So it’s possible they were in a degraded state - some but not all lights working? But yeah, that means they hit about the middle or maybe slightly higher of the mast.
 
At night, with only one light working, and flying below the top of the tower, to me it would seem very difficult to judge horizontal distance visually. Maybe impossible. Because you just have a single point to work with, and it's above you. There's nothing to judge distance by, and not really much to judge the relative position of it vs you. Above it? You can hopefully see it falling lower. Guy wires coming out at 45 degree angles or close to it just makes it worse.

Towers make me nervous in the daytime, let alone at night when I'm below the top.
 
Judging distance for an object straight ahead is not essential when you are flying. Just turn immediately, and then figure out if the turn is sharp enough.

I think the pilot was distracted by pointing out special places, and had no look ahead. Easy to do sightseeing.

Reminds me of a sightseeing flight over the Mark Twain reservoir with my father in law, at about 500 feet AGL. He pointed out a grey smudge off to the right, I studied it a few seconds, as the smudge grew, and black dots materialized in it. 5 jet fighters went by less than a mile in front of us, and well below us .

You cannot stop the swivel eyeball when pointing out the great sites that you are flying past.
 
Bell206 said:
Maybe. But they would be equally capable of other types of errors with the same consequences.
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It sounds like you've done a thorough analysis and accurately predicted the error rates for every scenario.
 
MountainDude said:
It sounds like you've done a thorough analysis and accurately predicted the error rates for every scenario.
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Not at all. Have just seen and repaired a lot of aircraft systems that would have caused the same end result if a pilot had not been onboard to intervene. My money is still on the carbon unit up front.
 
I've been in the computer field for 30 years. Software is slower and less reliable than it's ever been, and in terms of reliability I mean less deterministic and less well understood by any given person. It's already typically being written by teams of people working in an intentionally sped up pace, driven more by schedule than product specification. No other industry I know of except the entertainment industry works quite that way. And the latest fad is automating the code generation. Stuff like this makes the guy repeatedly pressing the reset circuit breaker button on the fuel pump seem cautious by comparison.
 
Albany Tom said:
I've been in the computer field for 30 years. Software is slower and less reliable than it's ever been, and in terms of reliability I mean less deterministic and less well understood by any given person. It's already typically being written by teams of people working in an intentionally sped up pace, driven more by schedule than product specification. No other industry I know of except the entertainment industry works quite that way. And the latest fad is automating the code generation. Stuff like this makes the guy repeatedly pressing the reset circuit breaker button on the fuel pump seem cautious by comparison.
Click to expand...
Politics and software: you don’t want to know how the sausage is made.
 
Albany Tom said:
I've been in the computer field for 30 years. Software is slower and less reliable than it's ever been, and in terms of reliability I mean less deterministic and less well understood by any given person. It's already typically being written by teams of people working in an intentionally sped up pace, driven more by schedule than product specification. No other industry I know of except the entertainment industry works quite that way. And the latest fad is automating the code generation. Stuff like this makes the guy repeatedly pressing the reset circuit breaker button on the fuel pump seem cautious by comparison.
Click to expand...
How much experience do you have with DAL-A software and DO-178? In my experience (on the DAL-A side) most generic 'software' people are not aware of the extent of validation and verification that goes into flight-critical software. That does not mean there are not unforseen problems and consequences, but it's far from the code free for all some would have you believe.

Nauga,
pushing and pulling
 
Piperonca said:
Politics and software: you don’t want to know how the sausage is made.
Click to expand...
But it's probably better to know how the sausage is made before yelling about problems with how it's made. ;)

Nauga,
who is mostly observable and controllable
 
Below DAL A, the yelling starts when engineers may want for example a minimum of DAL C for something but the PM says not today. At least that’s been my observation. And there’s always a need for good faith in the process, otherwise it does devolve into politics.

Glad I retired before people start qualifying AI for manned flight. The ultimate black box testing.
 
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Piperonca said:
Below DAL A, the yelling starts when engineers may want for example a minimum of DAL C for something but the PM says not today. At least that’s been my observation. And there’s always a need for good faith in the process, otherwise it does devolve into politics.
Click to expand...
My observation has been that the cert authority also has a say in the design assurance level assigned to a system. PM can make a case for a lower DAL, but if the e.g. FAA says no it's not going to go the PM's way. Same goes for every other flight-critical component of an airplane, software or not. Of course we can all think of cases where software flaws have caused serious problems, but most of us can also think of catastrophic design 'escapes' not involving software.

Nauga,
contingent
 
nauga said:
My observation has been that the cert authority also has a say in the design assurance level assigned to a system. PM can make a case for a lower DAL, but if the e.g. FAA says no it's not going to go the PM's way. Same goes for every other flight-critical component of an airplane, software or not. Of course we can all think of cases where software flaws have caused serious problems, but most of us can also think of catastrophic design 'escapes' not involving software.

Nauga,
contingent
Click to expand...
I wasn't talking about the FAA. Think green suit.
 
Piperonca said:
I wasn't talking about the FAA. Think green suit.
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I've through it on the mil side as well, more often and more extensively than the civil side. There is certainly more willingness to accept risk but it's still not as simple as people with no flight-critical software experience seem to believe, and the process and issues are not limited to software. I've also seen firsthand the changes that had to be implemented in control laws and V&V processes to lower the equivalent of the DAL at the time because the green-suited cert authority was unwilling to accept the risk. Quite understandably, IMO. We can all cite corner cases but neither civilian nor military flight critical software development processes (or even general design and development processes, for that matter) are as trivial as much of the general computer-savvy public seems to believe.

Nauga,
and his code walkthrough
 
nauga said:
Nauga,
and his code walkthrough
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That's the ticket, right there. And do that for mission equipment also. So it all plays like a symphony, except for that one guy that randomly bangs the kettledrum for no apparent reason.
 
nauga said:
How much experience do you have with DAL-A software and DO-178? In my experience (on the DAL-A side) most generic 'software' people are not aware of the extent of validation and verification that goes into flight-critical software. That does not mean there are not unforseen problems and consequences, but it's far from the code free for all some would have you believe.

Nauga,
pushing and pulling
Click to expand...
None at all. But I'm pretty familiar with how people are taught to code coming out of college and in internships, and I'm quite familiar with the typical success of bolt-on standards, specifically around compliance, for software development in general. I won't argue that standards and verification can make things more reliable....but "generic software", including applications used in health care, finance, front and back end business systems and government ARE being done faster and with less oversight and accountability than ever. So while it may be possible for aerospace to carve out a special flow and system that will keep things reliable, my bet is that the rest of the industry is going to lead them down to their level.

I'll add that I hope long term I'm wrong, and that software will become simpler. The way things are headed? Doesn't seem very likely to me.
 
Haven't written code in decades, but a few years ago I had a loose leaf notebook of DO-178B highlighted and tabbed. Went to battle over parts of it, I did. Got the (mental) scars. One thing I learned is that competent task and user analysis is critical, yet is frequently sped through so fast people don't notice something missing and go ahead and code to meet schedule, milestones, deliverables, et al. At the end you write test cases, execute them, provide documentation and so on. All very pretty but there's still something missing. Eventually it will come out. Sooner or later the drum will thump.

All of a sudden (being slow in my old age) I had a thought: Did Boeing use DAL-A for MCAS?
 
It makes me sad to think of all the battles fought, lost and bled for over code. I think it speaks to how deep the engineering instinct is in the species. From wooden levers to multithreading... we care about the tools we make.
 
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