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Jan. 29th, 2020 08:46 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
camwynI had flight school yesterday. Ordinarily I fly on weekends, because night flying is not really a thing you do when learning unless you are specifically doing the mandatory hours of night flying needed for a certificate, but the weekends have been lousy lousy weather and when they haven't, I've been sick. And since this weekend is slated to involve snow and similarly lousy weather, I used a vacation day, slept somewhat later than usual, and had a flying lesson.
If you are interested in hearing about the rules that govern weather conditions and flying, and how- in my student understanding- they applied to the Kobe Bryant crash- then you're welcome to click the cut link. If not, then no worries, it's all cool.
Okay, so.
There are two basic super-broad categories of flying condition in the United States. They may apply to Canada or other countries, but right now I can only vouch for the American rules, because I'm not studying to fly anywhere other than the lower 48. They are VFR and IFR. VFR stands for Visual Flight Rules; these are the conditions under which any yoyo with a certificate, or a student cert plus an endorsement from their instructor, is allowed to fly. IFR is Instrument Flight Rules. Under IFR conditions, you aren't allowed to fly unless you've been trained in how to fly, navigate, etc. using only the information you get from your helicopter/airplane/gyroplane/etc's navigational and other instruments.
.... yes, gyroplane. Yes, they exist outside of steampunk. They fall under the category of 'rotorcraft', like helicopters, and there's a question on the written exam for Private Pilot (rotorcraft) that only applies to gyroplane controls. No, I don't know why they feel the need to put that in front of everyone who takes the rotorcraft exam. Anyway.
IFR rules are for when you can't see enough by just looking out the window to fly safely. They're also for when you fly in what's called class A airspace. I can go into painfully granular detail here about the classes of airspace, but for now, class A is everything between eighteen thousand feet above sea level and 60,000 feet above sea level. You have to be able to navigate by instruments only to fly in that airspace. (For the truly rules lawyerish, above 60,000 feet it's VFR rules again for some reason. Bear in mind that the only civilian plane capable of flying that high was the Concorde, and that today you'd have to be Felix Baumgartner, Joseph Kittinger, or someone of that nature to be at that altitude without some form of space- or espionage-related mission.) If the weather is crappy enough in a given area to make it hard to see, but not crappy enough to pose a serious danger to aircraft, they'll declare IFR conditions, and people who don't have the appropriate certifications are not allowed to take off.
If you can see well enough to navigate and manage, but the weather is dangerous anyway, aircraft can be grounded regardless. I mention this because one of the hazards of the sky is the fact that stable air masses often mean crummy visibility but low to no winds, while unstable air masses often mean lovely ten-mile visibility in all directions but the distinct impression that Enlil, god of wind and storm, has decided to punch your aircraft repeatedly in the ass without any warning.
The thing with IFR rules is that even if you have an IFR certification, you are still a human being flying with human sensory data, and it is really stupidly easy to get conflicting information from your senses and from the instruments. If you do not have a visible horizon, or if you cannot see the ground, and if your inner ear has been tossed around a bit, your eyes may decide that hey, you're TOTALLY flying straight and level. Or you're flying tilted at a weird angle that may or may not be related in any way to the actual tilt of your aircraft. Or- you get the picture. If you don't have accurate sensory information, you can't be expected to make accurate sensory judgments.
I'm not saying aircraft instruments are accurate all the time. They depend on input the same as a human sense organ does, and if an input sensor is screwed up then the instrument will be too- if your pitot tube is blocked, for example, your aircraft's instruments will swear up and down that you have no airspeed at all even if you are very visibly zooming along at ninety-plus knots. There have been several notorious crashes where a combination of a failed horizon indication instrument and a lack of visual reference have ended horribly. But by and large, a properly maintained and successfully tested set of instruments is less subject to providing false information than a human being's sense of balance and direction, when that human being has been deprived of full sensory information, like the ability to see where they are in relation to the ground/the horizon.
On the day that Mr. Bryant's helicopter, tail number N72EX, took off, the clouds over the region were overcast at 1300 feet. Horizontal visibility was about five miles; the air was hazy. The pilot was operating under VFR rules, because flying above the cloud layer would have required him to get the okay from air traffic control, and there are so many aircraft in that area that he would have had to wait an hour or more to get official clearance. He had to stay under the clouds and keep the ground in sight, which... that's kind of a problem. Some aircraft have warning systems on board that will inform you if you get too close to an obstacle. (The Wiki article on the Miracle On The Hudson includes a link to a transcript from the cockpit. The line "Too low. Terrain" appears repeatedly. That's the voice of an onboard system trying to say HELLO THERE IS A BRIDGE IN FRONT OF US or possibly THAT'S A RIVER, YOU KNOW THAT, RIGHT?) N72EX didn't have one of those systems. They're not required on helicopters and they're not always a good idea, because helicopters usually fly pretty low and the false positives would be overwhelming. The pilot of N72EX did ask the local air traffic control for a type of service called 'following', which is a constant stream of reports on nearby hazards, but he was flying too low for ATC to give him that info. For that to work you have to be far enough above the ground to distinguish your craft from everything around you.
This is not where the problem happened, so far as I can tell. The problem happened when he got into a situation involving another category of clearance.
See, VFR has a related category of rules, Special VFR. Special VFR clearance means that flight conditions are just over the line between 'I can see well enough to handle everything' and 'oh shit where did the airport go'. If you're in a situation where you have, say, an overcast cloud layer nine hundred feet above the ground, but visibility for a good six miles, it's not unusual to get special VFR clearance so you can operate without needing to be trained up on instruments alone. It has to be done in the vicinity of an airport, though, and the ground has to stay in sight of the pilot at all times. Airplane pilots have to have at least a mile of clear visibility for Special VFR clearance. Helicopter pilots just have to get the okay from air traffic control, and don't need the mile visibility minimum. However, they do have to stay within visual distance of the ground, and they are responsible for staying clear of obstacles, terrain, low-lying clouds, super heavy fog banks, etc.
Aaaand... yeah. Apparently the vicinity of N72EX's target airport was an area where the local landforms tended to channel wet, heavy air to a degree that often resulted in nasty fog. The last thing N72EX's pilot transmitted to air traffic control was that he was putting the helicopter into a climb to avoid a cloud layer. Given the terrain he may also have been trying to put extra distance between himself and the hills below. I don't know.
There's a thing called continued VFR flight into IFR conditions. This is when someone has visual flight rules clearance but proceeds into a situation where they can no longer see. It messes you up bad. Even if you've had IFR training, if you're not being careful and not prepared, you can freak out pretty quickly and make some really bad decisions if you find yourself in IFR without warning. It happens even to really experienced pilots. From what I understand, that seems to have been what happened to N72EX; it went from being five hundred feet above hilly ground to ZOOM upwards more than a thousand feet in a ridiculously short span of time, found itself in the cloud layer, and... after that we don't know. Might've been engine failure. Might've been the pilot making a super bad judgment call in a state of disorientation and trying to descend out of the clouds faster than he should've, which is a thing that happens. Not everyone is Sully or Eric Moody. (Look up British Airways 009, the Jakarta Incident, or the phrase 'navigating one's way up a badger's arse' for Moody's info.) Until they've gone through the flight recorder data and the transponder data and everything from ATC, we won't be sure.
But that's why a lot comes down to a pilot's judgment of flight conditions, safety, and urgency. The safest way to handle marginal weather and potentially dangerous conditions is to ask yourself whether it's genuinely necessary to take the chance of flying under conditions that might put you in a situation where you can't see what you need to see in order to maintain control. Decision making before takeoff is the most important kind of aeronautical decision making.
Extra reference links for those of you who might be interested:
https://en.wikipedia.org/wiki/Instrument_flight_rules
https://en.wikipedia.org/wiki/Visual_flight_rules
https://en.wikipedia.org/wiki/Sensory_illusions_in_aviation
https://en.wikipedia.org/wiki/British_Airways_Flight_9
https://military.wikia.org/wiki/7_Ps_(military_adage)
If you are interested in hearing about the rules that govern weather conditions and flying, and how- in my student understanding- they applied to the Kobe Bryant crash- then you're welcome to click the cut link. If not, then no worries, it's all cool.
Okay, so.
There are two basic super-broad categories of flying condition in the United States. They may apply to Canada or other countries, but right now I can only vouch for the American rules, because I'm not studying to fly anywhere other than the lower 48. They are VFR and IFR. VFR stands for Visual Flight Rules; these are the conditions under which any yoyo with a certificate, or a student cert plus an endorsement from their instructor, is allowed to fly. IFR is Instrument Flight Rules. Under IFR conditions, you aren't allowed to fly unless you've been trained in how to fly, navigate, etc. using only the information you get from your helicopter/airplane/gyroplane/etc's navigational and other instruments.
.... yes, gyroplane. Yes, they exist outside of steampunk. They fall under the category of 'rotorcraft', like helicopters, and there's a question on the written exam for Private Pilot (rotorcraft) that only applies to gyroplane controls. No, I don't know why they feel the need to put that in front of everyone who takes the rotorcraft exam. Anyway.
IFR rules are for when you can't see enough by just looking out the window to fly safely. They're also for when you fly in what's called class A airspace. I can go into painfully granular detail here about the classes of airspace, but for now, class A is everything between eighteen thousand feet above sea level and 60,000 feet above sea level. You have to be able to navigate by instruments only to fly in that airspace. (For the truly rules lawyerish, above 60,000 feet it's VFR rules again for some reason. Bear in mind that the only civilian plane capable of flying that high was the Concorde, and that today you'd have to be Felix Baumgartner, Joseph Kittinger, or someone of that nature to be at that altitude without some form of space- or espionage-related mission.) If the weather is crappy enough in a given area to make it hard to see, but not crappy enough to pose a serious danger to aircraft, they'll declare IFR conditions, and people who don't have the appropriate certifications are not allowed to take off.
If you can see well enough to navigate and manage, but the weather is dangerous anyway, aircraft can be grounded regardless. I mention this because one of the hazards of the sky is the fact that stable air masses often mean crummy visibility but low to no winds, while unstable air masses often mean lovely ten-mile visibility in all directions but the distinct impression that Enlil, god of wind and storm, has decided to punch your aircraft repeatedly in the ass without any warning.
The thing with IFR rules is that even if you have an IFR certification, you are still a human being flying with human sensory data, and it is really stupidly easy to get conflicting information from your senses and from the instruments. If you do not have a visible horizon, or if you cannot see the ground, and if your inner ear has been tossed around a bit, your eyes may decide that hey, you're TOTALLY flying straight and level. Or you're flying tilted at a weird angle that may or may not be related in any way to the actual tilt of your aircraft. Or- you get the picture. If you don't have accurate sensory information, you can't be expected to make accurate sensory judgments.
I'm not saying aircraft instruments are accurate all the time. They depend on input the same as a human sense organ does, and if an input sensor is screwed up then the instrument will be too- if your pitot tube is blocked, for example, your aircraft's instruments will swear up and down that you have no airspeed at all even if you are very visibly zooming along at ninety-plus knots. There have been several notorious crashes where a combination of a failed horizon indication instrument and a lack of visual reference have ended horribly. But by and large, a properly maintained and successfully tested set of instruments is less subject to providing false information than a human being's sense of balance and direction, when that human being has been deprived of full sensory information, like the ability to see where they are in relation to the ground/the horizon.
On the day that Mr. Bryant's helicopter, tail number N72EX, took off, the clouds over the region were overcast at 1300 feet. Horizontal visibility was about five miles; the air was hazy. The pilot was operating under VFR rules, because flying above the cloud layer would have required him to get the okay from air traffic control, and there are so many aircraft in that area that he would have had to wait an hour or more to get official clearance. He had to stay under the clouds and keep the ground in sight, which... that's kind of a problem. Some aircraft have warning systems on board that will inform you if you get too close to an obstacle. (The Wiki article on the Miracle On The Hudson includes a link to a transcript from the cockpit. The line "Too low. Terrain" appears repeatedly. That's the voice of an onboard system trying to say HELLO THERE IS A BRIDGE IN FRONT OF US or possibly THAT'S A RIVER, YOU KNOW THAT, RIGHT?) N72EX didn't have one of those systems. They're not required on helicopters and they're not always a good idea, because helicopters usually fly pretty low and the false positives would be overwhelming. The pilot of N72EX did ask the local air traffic control for a type of service called 'following', which is a constant stream of reports on nearby hazards, but he was flying too low for ATC to give him that info. For that to work you have to be far enough above the ground to distinguish your craft from everything around you.
This is not where the problem happened, so far as I can tell. The problem happened when he got into a situation involving another category of clearance.
See, VFR has a related category of rules, Special VFR. Special VFR clearance means that flight conditions are just over the line between 'I can see well enough to handle everything' and 'oh shit where did the airport go'. If you're in a situation where you have, say, an overcast cloud layer nine hundred feet above the ground, but visibility for a good six miles, it's not unusual to get special VFR clearance so you can operate without needing to be trained up on instruments alone. It has to be done in the vicinity of an airport, though, and the ground has to stay in sight of the pilot at all times. Airplane pilots have to have at least a mile of clear visibility for Special VFR clearance. Helicopter pilots just have to get the okay from air traffic control, and don't need the mile visibility minimum. However, they do have to stay within visual distance of the ground, and they are responsible for staying clear of obstacles, terrain, low-lying clouds, super heavy fog banks, etc.
Aaaand... yeah. Apparently the vicinity of N72EX's target airport was an area where the local landforms tended to channel wet, heavy air to a degree that often resulted in nasty fog. The last thing N72EX's pilot transmitted to air traffic control was that he was putting the helicopter into a climb to avoid a cloud layer. Given the terrain he may also have been trying to put extra distance between himself and the hills below. I don't know.
There's a thing called continued VFR flight into IFR conditions. This is when someone has visual flight rules clearance but proceeds into a situation where they can no longer see. It messes you up bad. Even if you've had IFR training, if you're not being careful and not prepared, you can freak out pretty quickly and make some really bad decisions if you find yourself in IFR without warning. It happens even to really experienced pilots. From what I understand, that seems to have been what happened to N72EX; it went from being five hundred feet above hilly ground to ZOOM upwards more than a thousand feet in a ridiculously short span of time, found itself in the cloud layer, and... after that we don't know. Might've been engine failure. Might've been the pilot making a super bad judgment call in a state of disorientation and trying to descend out of the clouds faster than he should've, which is a thing that happens. Not everyone is Sully or Eric Moody. (Look up British Airways 009, the Jakarta Incident, or the phrase 'navigating one's way up a badger's arse' for Moody's info.) Until they've gone through the flight recorder data and the transponder data and everything from ATC, we won't be sure.
But that's why a lot comes down to a pilot's judgment of flight conditions, safety, and urgency. The safest way to handle marginal weather and potentially dangerous conditions is to ask yourself whether it's genuinely necessary to take the chance of flying under conditions that might put you in a situation where you can't see what you need to see in order to maintain control. Decision making before takeoff is the most important kind of aeronautical decision making.
Extra reference links for those of you who might be interested:
https://en.wikipedia.org/wiki/Instrument_flight_rules
https://en.wikipedia.org/wiki/Visual_flight_rules
https://en.wikipedia.org/wiki/Sensory_illusions_in_aviation
https://en.wikipedia.org/wiki/British_Airways_Flight_9
https://military.wikia.org/wiki/7_Ps_(military_adage)
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Date: 2020-02-01 11:12 pm (UTC)