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

it's just before 10 o'clock on the night of December 19 2011 in a house near Bryan Texas the gentle patter of light rain is suddenly interrupted by a sound like an explosion loud and violent but not like thunder outside in what has now become a deluge the source of the noise soon becomes apparent a short distance away strung out and shattered into a dozen pieces lie the barely recognisable remains of a light aircraft its five occupants beyond help soon emergency responders are on site documenting the scene doing what has to be done there's one simple question on everyone's mind what went wrong PDI accurate the story that ends in that dark rain-drenched farmyard begins nine hours earlier and four states away in Hampton Georgia where a pilot is preflighting his Piper Cherokee six he'll be joined on today's flight by his wife brother and two young children their destination is Waco Texas thirty-three years old the Private Pilot has just shy of 400 hours total time nearly all of it in this airplane November 3 five Niner zero tengo he's held an instrument rating for just over two years and has logged a total of 14 hours in actual IMC by the standards of most pilots he flies quite a bit 46 hours in the past three months shortly before 2 p.m. Eastern time 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 6 p.m. Central now progress is slow strong winds aloft out of the southwest push ground speeds into double digits and weather looms ahead a strong north-south line of thunderstorms between the aircraft and its destination at 8:20 p.m. the pilot is handed off to Houston center and discusses his plans with the controller in the center gravy to get a member three five Niner zero tango with you love with a South the three five Niners your tango used some sahaja Love Canal camera two Niner a day I have to say talk too much about the weather your speed it could change all the other time you get there but as of the current moment the worst of the weather you have to face I believe is a line from about 30 miles due west of College Station up the north as far as I can see all right yes sir we'll wash it off with X rats oh I wish go play fire on the evening of the accident a low-pressure area centered over the Texas Panhandle dominated the regional weather map this in combination with other factors including a stationary front a warm moist airmass and significant atmospheric instability created strong potential for convective activity over central and eastern Texas by mid evening potential had become reality by the time the pilot procced into Texas a long line of storms was slicing northeastward toward him at upwards of 45 knots to convective cygnets had already been issued by that point the first at 7:55 p.m. the second one hour later both warned of a fast moving line with severe embedded thunderstorms and tops above 45,000 feet the pilot was notified of the second segment by Houston center it's not clear what the pilot knew about the weather prior to the flight he did however have a Garmin 696 GPS receiver and an XM satellite weather subscription which allowed him to overlay NEXRAD radar on a moving map and access a variety of other weather information whatever his earlier knowledge though it's clear that by 9:00 p.m. the pilot was well aware of the line of precipitation between him and his destination what's less clear is whether he grasped the true level of danger it represented given the outcome of the flight the following discussion during a shift change at Houston Center has an ominous tone I will talk with this fellow his route goes right at Lian and goes hard back up and he pretty much took me off on anything I wanted to do he said he'd rather just play it by ear in his defense he's really slow and it is moving north but at some point I won't talk to him it's now 9 19 p.m. Central Time and the pilot has just been handed off to Houston TRACON normally he wouldn't be this far south but he's diverted significantly off course to avoid the weather now he seems eager to turn back toward his destination approach good evening to get the river three cops honor to thank you with you level they selves over 35 Nigel Tango Houston approach it looks like you're president headings uh good for about forty miles and should be able to make a right turn toward TSTC yeah yeah what I was looking out my sex read is what's a hit lianna's maybe take about a two five zero heading from the wall I'd be alright yeah I don't know that 250 of foot units of moderate to heavy precip for what I'm showing right now okay wall prophetic yeah you're looking good right now so about twenty miles north and college and you can start bending it to the right there's some pretty good gaps and the weather once you get around that area okay Roger that twelve minutes later the controller's radar shows the aircraft edging closer to the weather when I zero tango for what I'm showing your skirt and right along the edge of a light to moderate precipitation area yeah the psychiatrist tries to uh boots out that it's not the hole to go through I get to my father works there for already oh another thing I do have a heavy too extreme cell at your one to two o'clock and about eight miles looks like once you get on the backside of that you can make a right turn toward TSTC project review with the help ascetic right here to it just after that that works for me another five minutes go by and the aircraft is now very close to the area of heavy precip the controller mentioned earlier now is your tango you getting any lightning off the right there now I haven't been seen any bumblebee yeah I go on left about 50 degrees here for just about three or three minutes deafening that's fine now as you're able you can turn right direct to TSTC okay up showeth a pretty good storm here to my eyes it works out to be patentable turn right but okay that's what I'm showing five minutes later the controller is advising the pilot that more weather may be moving into the Waco area when he notices something odd on his radar scope over 35.0 tango houston yeah I go ahead here it looks like you made a left 360 on me what's going on then Arobin on 0/10 got show you headed right into the heavy weather now I would suggest you turn back right to about a two to zero heading by the time the pilot had gotten within close proximity to a fast-moving area of heavy precip he was already in danger but exactly how much danger depended on just how close around severe weather relatively minor changes in location can mean major differences in flight conditions which is one of the reasons why light aircraft in particular should stay well away from such weather in this case it was close proximity to the storm that brought a small but important detail into play the datalink radar display the pilot was using does not provide a real-time picture of the weather it typically takes several minutes for the next rad ground station to complete the scans necessary to build an image and added to that is the minute or so it takes to transmit the image to the aircraft the total time lag that night varied between six and eight minutes a long time around storms moving at 45 knots it's not clear what understanding the pilot had of this but even if he knew about the possibility of significant time lag there was another potentially confusing factor the age indicator on his display would have initially shown the time it took for the image to be transmitted to the aircraft not the total time to create the image in other words while the pilot was seeing the weather as it existed roughly eight minutes earlier the display was telling him that the data was only one minute old here's what that difference meant in reality in these images we see where the aircraft actually was in relation to the weather and in these we see where the pilot likely thought it was and there will be nonzero tango show you headed right into the heavy weather now I would suggest you turn back right about a 2 to 0 heading it's now 9:42 p.m. and the pilot fighting to maintain control of the aircraft personally acknowledges the controllers warning they are the last words anyone will hear from November 3 five Niner zero tango okay yeah what's alright where's the bad weather yeah we'll try to get out of it all the controller can do is watch as the aircraft completes an abrupt 180 degree right turn and starts to descend when radar contact is lost it's headed Northwest passing through 6800 feet airspeed building rapidly in the seconds that follow the wing spar snaps the left wing separates from the fuselage and gravity takes control there's nothing new about thunderstorm related accidents for as long as people have been flying they've been straying into convective activity and sometimes paying a heavy price for it what is new for most of us is in cockpit weather NEXRAD radar images transmitted via datalink provide a vastly better picture of the weather than we had in the past in some respects even better than onboard radar useful as it is though the technology has limitations time delay being perhaps the most significant in benign weather it's rarely a problem but around a storm that may be covering six or more miles during the delay period it can mean the difference between life and death that in the starkest possible terms is why it's a bad idea to use datalink radar to pick your way through severe weather especially in low visibility conditions but there's a larger issue as well even if the pilot had been as far from the storm as he believed he may not have been safe radar shows precipitation but in a thunderstorm it's the turbulence that's really dangerous there is a correlation between the two but aircraft destroying turbulence can and often does exist outside of heavy rain it's also worth considering the role that factors like fatigue and hypoxia may have played there's no way to be certain but after almost nine hours at relatively high altitude it seems likely that the pilot's judgment was impaired to at least some degree in short there are several lessons for pilots here awareness of data link time lag is important but more critical is a healthy respect for the sheer power of severe weather if a system is moving faster than 15 or 20 knots if it has tops over 30,000 feet if a convective segment has been issued don't get close enough to make time lag a factor steer around the whole area or land and wait it out the latter option was open to the pilot of three five Niner zero tango until just minutes before the final plunge he could have turned 90 degrees to the weather and headed for safety it would have meant a late arrival but at least they would have arrived

Channel: Air Safety Institute

Views: 1,209,550

Rating: 4.8613257 out of 5

Keywords: airplane, plane crash, airport, aviation weather, pilot, emergency, safety, risk management, thunderstorm, airplane crash, decision making, air crash investigation, flight plan, vfr, ifr, air traffic control, flight safety, safety tips, flight training, aviation safety, airplane accidents, general aviation, cockpit weather, data link, Nexrad

Id: 83uvKWJS2os

Length: 12min 36sec (756 seconds)

Published: Wed Jun 11 2014

Reddit Comments

[u/Lonk715BW]

Thanks for sharing, that's a great video. Learning about accidents like these could save your life.

[u/[deleted]]

I've seen this firsthand. I have SXM weather, and was flying around some precipitation columns. Even thought the display said -0:01 or whatever, the rain columns were visibly 5-10 miles from where the radar said they would be. NEXRAD is an awesome tool but should be relied on with extreme caution.

[u/SleepyAviator]

Thanks for the video. I moved to College Station a few days before this happened so it hit close to home. Weather out there was wild as it was in Dallas. Since then I've moved to West Texas, now we get crazy weather and mountains. Yippee!

[u/Spitfire222]

These videos are excellent, and I'm really glad AOPA makes them. We watch one at each of my flying club's meeting after we've finished the usual aircraft status reports, and then have a short discussion about it afterwards about how we can apply the lessons from that video to our flying.

[u/im2lazy789]

Out of all the ASI videos - this one gives me the most chills, at least once a week my mind will wonder back to this video, probably because I could see myself making this mistake when deep in the soup looking at your displays for where the weather is.