On Thursday night, JetBlue flight 429 hit severe turbulence over South Dakota, sending 24 passengers and crew to the hospital. This turbulence, associated with a line of thunderstorms, resulted in the abrupt termination of the Boston to Sacramento flight, with an emergency landing in Rapid City, South Dakota.
This blog will analyze the meteorology of this event and examine whether it was possible to foresee and avoid this terrifying incident. (Answer: it was). Strangely enough, I was only a few miles from the incident, traveling on an Alaska Airlines flight between Baltimore and Seattle.
The Details
The actual flight path of JetBlue 429 is shown below with information from the FlightAware website. Weather radar information, but from a later time, is also shown.
A key problem for the JetBlue captain was to avoid the turbulence associated with convection (thunderstorm) over much of his/her route.
To analyze the situation we need to know the exact time and location of the incident. FlightAware provides minute by minute information and I have selected (below) the period of interest before the aircraft was diverted (at 0716 PM Mountain Time or 0116 UTC UTC). Looking the previous few minutes, you will notice they were flying at 33,400 ft and then dropped suddenly by 100 feet at 0714 PM. I suspect that is the time of the incident.
Then they returned to their previous altitude. The location at that time is provided and I plotted it on the map below. The position is in south/central South Dakota.
Now we are ready to investigate the meteorology of the incident. Let's start by looking at the radar imagery, based on the National Weather Service radars in the region (image from the NCAR RAP website). Here is the radar reflectivity at 0115 UTC, with an oval showing the aircraft location. Red indicates high reflectivity, which is associated with heavy rainfall, strong vertical velocity, and lots of turbulence. You want to avoid reds if you are in an aircraft.
Clearly, you can see the problem: the plane flew into a very active portion of the thunderstorm complex. Notice the arching shape of the red colors: this is indicative of a very vigorous system. In short, the aircraft entered a line of very strong convection, a region that all aircraft should avoid. Strong midwest thunderstorms frequently grow to 40,000 to 50,000 feet and turbulence can exist above them due to upward propagating waves.
Here is a blow up so you can see the situation more clearly.
So how did this line of thunderstorms develop in the previous hour? Did the pilot have time to avoid them? To answer this question, let's look at a series of radar images prior to the incident and I will indicate the location of the plane on the imagery.
At 0100 UTC, 13 minutes before the emergency, the aircraft was well upstream of the convective line, with plenty of time to move around it (see below).
Ten minutes before that (0050 UTC), the convective line was apparent, with over 20 minutes to find a path around it.
During the prior hour, the convective line was strengthening and moving to the NE, something that is evident by looking at a series of radar images (found here).
Normally, pilots fly around major convective lines like this. There was plenty of time to get around it, and an excellent flight path to the south of the line existed. So why did the pilot fail to avoid this dangerous feature?
One possibility was that the pilot did not have access to the real-time radar imagery shown above. Pilots can view their aircraft weather radar, but as described later, such radars have limitations. The radar I showed you above is available in a number of forms on the internet and a wide variety of web sites. As a passenger, you can view the radar imagery in real-time at your seat using a laptop/pad and onboard internet services (like Gogo). In fact, that evening I was following the weather on my Alaska Airlines plane, a few hundred miles away (although Gogo was really poor on my aircraft). Unfortunately, many airlines do not provide such real-time radar data (from the National Weather Service radar) to their pilots, and I assume this is true of JetBlue. No pilot would knowingly fly into such a severe line of convection.
What about weather radars on aircraft? They are helpful, but provide only a localized view of the precipitation situation and possess relatively small antennas that do not give high-resolution information. This is certainly true of the radar on the Airbus 320 (shown below), which was the aircraft involved in this flight (see below).
I assume that the aircraft radar did show the strong line ahead of the aircraft during the final few minutes before the incident, yet the pilot decided to punch through. A mistake.
My Flight
As noted earlier, I was on Alaska 761 that left at nearly the same time from Baltimore and followed a route roughly 200 miles to the north of JetBlue 429 over South Dakota (see below). Our pilot skirted north of that convective feature, with light to occasionally moderate turbulence (seat belt sign was on for most of it).
The Bottom Line
For some reason, JetBlue 429 headed directly into a strong convective line. It should not have done do. Radar imagery clearly showed the threat and there was plenty of time to avoid it. Pilots should have access to the same detailed radar imagery that folks in coach with laptops (like myself) can readily access. They should also receive the training necessary to understand the impacts of various types of convection. My own conversations with pilots suggest that many do not have sufficient meteorological knowledge and this should be addressed. With proper use of weather radar and good pilot training, incidents like the JetBlue 429 one should be avoidable.
Destroyed toilet in JetBlue 429.
You don't see this happening in Boeing aircraft
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