Accident Case Study: Time Lapse – misunderstanding in-cockpit weather displays can lead to tragedy

It is shortly before 10:00 pm on December 19, 2011 in a house near Brian Texas, the gentle patter of light rain is suddenly interrupted by a sound like a loud and violent explosion, but not like thunder. outside in what has now become a deluge. The source of the noise soon becomes evident a short distance away, hanging and smashed into a dozen pieces, lie the barely recognizable remains of a small plane, its five OCCs and beyond help, soon the emergency services are on the scene documenting the scene doing what needs to be done there. One simple question on everyone's mind: What went wrong in today's St?

I don't think my CBI is accurate. The story that ends in that dark rain-soaked farm yard begins 9 hours earlier and four states away, in Hampton, Georgia, where a pilot is conducting the pre-flight. His Piper Cherokee 6 will be accompanied on today's flight by his wife, his brother and his two young children. Their destination is Waco, Texas. 33 years old, the private pilot has just under 400 hours of total

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, almost everything on this plane November 35 ner0 Tango He has had an instrument rating for just over 2 years and has logged a total of 14 hours in actual IMC by most pilots' standards.

He flies pretty much 46 hours in the last 3 months, just before 2:p. m. ET, pilot and passengers head west on an IFR flight plan, everything is routine after a planned fuel stop in Jackson Mississippi, they depart again just before 600 p.m. Now progress is slow, strong downwind winds from the southwest push ground speeds into double digits, and the

weather

is looming with a strong line of north-south thunderstorms between the plane and its destination at 8:20 p.m. the pilot is delivered to the Houston Center and discusses his plans with the controller Houston Center good evening, you have Nov 359 Tango with your level at 8,000 359 Z Tango Houston C Tim 298 I had to say that you talk too much about the

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, your speed could change all together the

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you get there, but as of now, the worst weather you should have, I think, is in line from about 30 Mi Due west of Colge station all the way north, as far as I can see, okay , yes sir.

We're looking at the next R, so we're going to continue here on the night of the

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, an area of ​​low pressure centered over the Texas Handle dominated the regional weather map, this in combination with other factors, including a stationary front. A warm, moist air mass and significant atmospheric instability created a strong potential for convective activity over central and eastern Texas. By mid-afternoon, potential had become reality as the pilot crossed into Texas, a long line of storms heading northeast toward him at more than 45 knots. At that time, two convective signals had already been emitted, the first at 7:55 p.m. the second, 1 hour later, both warned of a fast-moving line with severe thunderstorms and peaks above 45,000 feet.

The Houston center notified the pilot of the second signal. It is unclear what the pilot knew about the weather before the flight. However, he did. a Garmin 696 GPS receiver and an The pilot was well aware of the line of fall between him and his destination. What is less clear is whether he understood the true level of danger he posed given the outcome of the flight. The following discussion during a shift change at the Houston Center has an ominous tone. I had a little chat with this guy, his route goes straight to Leona and comes back hard up and he pretty much diverted me from anything I wanted to do, he said he'd rather play by ear on his defense, he's very slow and moving towards the n M, but at some point you might want to talk to him.

It is now 9:19 p.m. m. Central time and the pilot has just been handed over to Houston Tron. He normally wouldn't be this far south, but he veered significantly off course to avoid the weather. He now seems eager to return to his destination. Good evening, you have November 35, 9. Tango with you level 8000 35 90 Tango we are approaching, it looks like your current bearings are good for about 40 miles, you should be able to turn right towards TSTC, okay, yes, what was looking at my next R is a big hit. Leona may be heading towards 250 for a while, that will be fine, yeah, I don't know if 250 will put you in some moderate to heavy precept, uh, for what I'm showing right now, okay, we'll keep the setup.

Yeah, you're looking good right now to about 20 miles north of the university and you can start turning it to the right. There are some pretty good differences in the weather once you get through that area. Well, Roger, 12 minutes later, the controller's radar shows the plane. Approaching Z Tango weather from what I'm showing, you're skirting the edge of an area of ​​light to moderate precipitation. Yes, I'm seeing the same thing. I'm just trying to move south and find a hole. to pass without going too far from the air for everyone here or 0 Tang. I have a very heavy to extreme cell between 1 and 2:00 and about 8 miles, it seems like once you get to the back of that. uh you can turn right towards uh TSTC rer just keep this setting here so we understand that works for me.

Another 5 minutes pass and the aircraft is now very close to the heavy prip area that the controller mentioned earlier 0o tangle, are you getting any lightning from the right? No, I haven't seen any, but I'm going to go left about 15° here for about 2 or 3 minutes, okay, okay, as you can. you can turn right straight into TSTC, okay, I'm showing a pretty good storm here to my right that we're about to pass and we'll turn right after that, okay, that's what I'm showing 5 minutes later, the controller is warning. to the pilot who may be moving more weather towards the Waco area when he notices something strange in his radar range 35 n Tango Houston yeah go ahead Houston it looks like you turned 360 left on me what's going on and 90 T , I show you that you headed to the right.

With the bad weather now, I would suggest that he turn right to a heading of 220. By the time the pilot approached a fast moving area with a lot of pressure, he was already in danger, but Exactly how much danger depended on how close he was around. Severe Weather Relatively minor changes in location can mean major differences in flying conditions, which is one reason why light aircraft in particular should stay away from such weather. In this

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, it was the proximity to the storm that provided a small but important detail. Replaying the datalink radar display the pilot was using does not provide a real-time picture of the weather.

The Next Rad ground station typically takes several minutes to complete the scans needed to create an image, adding to that the minute or so it takes. To transmit the image to the plane, the total delay that night varied between 6 and 8 minutes, a lot of time around storms moving at 45 knots, it is not clear what understanding the pilot had of this, but even if he was aware of the possibility of a significant delay. There was another potentially confusing factor: The age indicator on its screen would have initially shown the time it took for the image to be transmitted to the plane, not the total time to create the image - in other words, while the pilot saw the weather as it existed.

About 8 minutes earlier, the screen was telling you that the data was only 1 minute old. This is what that difference actually meant. In these images we see where the plane actually was in relation to the weather and in these we see where the pilot probably thought. era and 90 T show that you were heading into bad weather now I suggest you turn right back to about a heading 220, it is now 9:42 p.m. M and the pilot struggling to maintain control of the Turly aircraft acknowledge the controller's warning, they are the last words anyone will hear starting November 35th. ner0 Tango, okay, yes, we are right, we have bad weather.

I'm going to try to get it. Outside of this, all the controller can do is watch as the aircraft completes a sharp 180° right turn and begins to descend when contact with the radar is lost. It heads northwest and passes through an airspeed of 6,800 feet that increases rapidly in the seconds following the wings. Spar breaks the left wing separates from the fuselage and gravity takes control. There is nothing new about storm-related

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s, because for as long as people have been flying, they have strayed into convective activity and sometimes pay a high price for it. What's new for most of us is Cockpit Weather Nexrad radar images transmitted over a data link provide a much better weather picture than we had in the past, in some respects even better than radar on board.

It is useful, although the technology has limitations. The time delay is perhaps the most significant in mild weather conditions. It's rarely a problem, but around a storm that can cover six or more miles during the lag period can mean the difference between life and death and, in the crudest terms possible, that's why it's a bad idea. use a datalink radar to choose the path. in severe weather conditions, especially in low visibility conditions, but there is also a bigger problem, even if the pilot had been as far from the storm as he thought he might not have been sure, the radar shows precipitation, but in a storm what What is really dangerous is the turbulence.

There is a correlation between the two, but the turbulence that destroys airplanes can and often does exist outside of heavy rain. It is also worth considering the role that factors such as fatigue and hypoxia may have played. There's no way to know for sure, but after almost 9 hours at a relatively high altitude, it seems. It is likely that the pilot's judgment was affected at least to some extent. In short, there are several lessons here for pilots. Awareness of data link delay is important, but more critical is a healthy respect for the raw power of severe weather if a system is moving faster than 15 or 20 knots if it has peaks over 30,000 feet if a warning has been issued convective segment do not get close enough for time delay to be a factor, circle around the entire area or land and wait for it to pass, the ladder option was open to the 35 ner0 Tango pilot until a few minutes before the final dive could have turned 90° to the weather and headed towards safety, it would have meant arriving late, but at least they would have arrived.