American Airlines crash

billvon said:
But any system that uses barometric pressure is subject to some error, since many things affect air pressure as read by an aircraft vs on the ground.
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Stupidly I found myself wondering why they don't all use laser altimeters like those Greenland ice sheet overflights do...then the brain fog lifted. Can't use a system that's only a fair weather friend. (plus the other forehead smack I gave myself, regarding attenuation at high altitude) Still, made me wonder if there could someday be a better cloud/mist penetrating laser that would be the altimeter to end all other altimeters. (this of course might be the sort of high energy device that barbecues people's eyeballs as they look up, so this may be an innovation dead end...)
 
TheVat said:
Stupidly I found myself wondering why they don't all use laser altimeters like those Greenland ice sheet overflights do...then the brain fog lifted. Can't use a system that's only a fair weather friend. (plus the other forehead smack I gave myself, regarding attenuation at high altitude) Still, made me wonder if there could someday be a better cloud/mist penetrating laser that would be the altimeter to end all other altimeters. (this of course might be the sort of high energy device that barbecues people's eyeballs as they look up, so this may be an innovation dead end...)
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Maybe it would just be better to not have a helicopter route running under a busy runway glide slope?
 
As is the case in most serious airline accidents these days, I suspect that when the investigation of this incident is done there will be not just a single cause identified, by a combination of several contributing factors.

Major questions at this time include:
  • If, as seems likely, the collision happened at an altitude of 325+/- 25 feet, why was the helicopter at that height, since its flight ceiling was supposed to be 200 feet?
  • Was the helicopter's barometric pressure on the altimeter set correctly, or did the helicopter pilot believe she was flying lower than she was?
  • Why did the air traffic controller give the helicopter pilot permission to proceed on visual sighting of the oncoming aircraft, when there was clear room for doubt about whether the helicopter pilot had identified the correct?
  • If the helicopter pilot was not certain that she had spotted the oncoming aircraft, why did she not slow down or hover, or make a turn to be sure that the helicopter would avoid the landing aircraft? After all, it was obvious where the plane was headed.
  • Why was air traffic control not proactive about directing the helicopter to slow down, stop or turn?
  • Were the regulations designed to maintain safe separation of aircraft for this particular airport deficient?
  • Was the helicopter pilot wearing night vision goggles at the time of the collision, which probably would not have improved her vision in the specific circumstances? If that was the case, why were they being worn?
  • Was the helicopter flying too fast?
  • Was the helicopter pilot's vision obscured by the large central console in the Blackhawk?
  • Did the forward tilt of the helicopter contribute to limited vision on the part of the helicopter pilot?
  • Did collision warning system alarms go off in one or both of the aircraft? If so, were they ignored, or did time just run out due to other factors? If they were ignored, why were they ignored?
  • Was it safe for the military helicopter and the commercial jet to be communicating on frequencies that meant that neither pilot could hear what the other was saying? Should procedures be amended?
 
TheVat said:
Stupidly I found myself wondering why they don't all use laser altimeters like those Greenland ice sheet overflights do...then the brain fog lifted. Can't use a system that's only a fair weather friend. (plus the other forehead smack I gave myself, regarding attenuation at high altitude) Still, made me wonder if there could someday be a better cloud/mist penetrating laser that would be the altimeter to end all other altimeters.
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Sure, radar altimeters. Most airliners use them now. They work as long as 1) you are close to the ground and 2) the radar horn is pointed down. They are invaluable for instrument landings where you can't see the runway until very low altitudes, or at all. Having the system count down your altitude from 500 feet to 10 feet is very, very useful in order to time your flare.

However, they give you altitude AGL (above ground level.) So when you're over a mountain and you fly over a cliff, the AGL altitude will suddenly increase by a thousand feet - and per your instruments, an aircraft behind you, previously on level, is suddenly 1000 feet lower than you. So very useful to avoid hitting things, not so useful when you want to keep aircraft apart.

Most collision avoidance systems use altitude MSL (above mean sea level.) That's the same everywhere on the planet, and so is more useful to avoid collisions.
 
Seattle said:
Maybe it would just be better to not have a helicopter route running under a busy runway glide slope?
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Sure, it would be better if there were less traffic. But for the past 100 years or so air traffic control has been a tradeoff between the needs of hundreds, then thousands then millions of users - from airline passengers to medevac flights to police to military to firefighting to student training. All think their mission is the most important. For the most part ATC has done a very good job of accommodating them all.

And the result of this incident may be that they have to shut down or relocate Route 4, whether for practical reasons or because of public outcry. But it's not going to be practical to reroute all helicopter routes above approach routes; helicopters necessarily operate near airports, and generally it's safer for them to be lower than higher.
 
billvon said:
Sure, it would be better if there were less traffic. But for the past 100 years or so air traffic has been a tradeoff between the needs of millions of users - from airline passengers to medevac flights to police to military to firefighting to student training. All think their mission is the most important. For the most part ATC has done a very good job of accommodating them all.

And while the result of this incident may be that they have to shut down or relocate Route 4, whether for practical reasons or because of public outcry. But it's not going to be practical to reroute all helicopter routes above approach routes; helicopters necessarily operate near airports, and generally it's safer for them to be lower than higher.
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Sure, it's also generally safer for them not to cross approaches. You also generally cross busy airports, where you aren't landing, at the midpoint where you are above all landings/takeoffs.
 
Seattle said:
Sure, it's also generally safer for them not to cross approaches. You also generally cross busy airports, where you aren't landing, at the midpoint where you are above all landings/takeoffs.
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And that works well - until there's a go-around.

There are no perfect solutions, but some tradeoffs are better than others.
 
Should we feel confident to fly? I'm supposed to fly out in a few months to see relatives, and I'm not feeling it. Even if it's rare, I've never felt stressed or thought of the plane actually crashing, although I've always known it's a possibility.
 
wegs said:
Should we feel confident to fly? I'm supposed to fly out in a few months to see relatives, and I'm not feeling it. Even if it's rare, I've never felt stressed or thought of the plane actually crashing, although I've always known it's a possibility.
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Still rare as hens teeth. Just think stats, you will be good
 
billvon said:
I think you should feel as confident as you did six months ago, barring any more ATC firings/losses. It is still very safe overall.
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''Overall.'' :eek:

I guess that there's no perfect world, where it could never happen. I'm amazed so many flights happen every day, without incident. It's pretty remarkable, when you stop to think about it.
 
wegs said:
Should we feel confident to fly? I'm supposed to fly out in a few months to see relatives, and I'm not feeling it. Even if it's rare, I've never felt stressed or thought of the plane actually crashing, although I've always known it's a possibility.
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No problem at all, in fact you should be more concerned with the ride to the airport than the flight itself. ;)
 
(Q) said:
No problem at all, in fact you should be more concerned with the ride to the airport than the flight itself. ;)
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I keep hearing/reading this stat; of course there are more car accidents and such - we fly so much less than we drive (unless you're the pilot or flight attendants), so that's why the odds of being killed in a plane crash are way less. Not because driving is more dangerous. This is my logic, and I'm sticking to it. :rolleyes:
 
wegs said:
It's pretty remarkable, when you stop to think about it.
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Yep. The system does really work pretty well.

There's an old saying that the FAR's (federal air regulations) were written in blood. When you read them today you can pick out which new rules have come about because of a specific accident or incident. The good news for us is that so many mistakes have been made - and so many procedural/regulatory holes have been plugged - that we now have the benefit of all those 100+ years of experience, making mistakes and fixing the problems.
 
wegs said:
I keep hearing/reading this stat; of course there are more car accidents and such - we fly so much less than we drive (unless you're the pilot or flight attendants), so that's why the odds of being killed in a plane crash are way less. Not because driving is more dangerous. This is my logic, and I'm sticking to it. :rolleyes:
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Even if you flew instead of driving every single day that would be true. And even if you flew 1000 miles every day instead of driving 100.

The fatality rate for people traveling by air here in the US is .003 deaths per 100 million miles flown, vs 0.570 per 100 million miles driven. In commercial aviation at least.
 
billvon said:
I think you should feel as confident as you did six months ago, barring any more ATC firings/losses. It is still very safe overall.
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But isn't ATC these days mostly comprised of epileptics and lunatics? That's what Trump said. (If I had only known a few decades back about the apparent joys of air traffic control for epileptics...)
 
parmalee said:
But isn't ATC these days mostly comprised of epileptics and lunatics?
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Well, if that's true, they are doing way better than the 1950's version of ATC (all white straight boring men) is doing; you know, back when America was great. In 1955 there were SEVEN fatal crashes in the US - and three could have potentially been avoided if ATC had been paying more attention.
 
billvon said:
Even if you flew instead of driving every single day that would be true. And even if you flew 1000 miles every day instead of driving 100.

The fatality rate for people traveling by air here in the US is .003 deaths per 100 million miles flown, vs 0.570 per 100 million miles driven. In commercial aviation at least.
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I would assume this is due to the number of fatal crashes per mile traveled being dramatically lower in aviation compared to road travel, though. They say most car accidents in general happen a few miles away from your home. On average, aviation accidents are rare events, and sure, because there is greater safety oversight, but we’re not “surrounded” by other flying planes during a flight, like we are in cars, when we’re driving on say multi-lane highways. I believe what you’re saying but does this make any sense?
 
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