Updated: Mar 25
Update: The NTSB preliminary report for this accident indicated...
"The flight crew reported that they did not experience any remarkable turbulence during the flight, nor during the time immediately surrounding the in-flight upset event."
A Bombardier Challenger 300 with a callsign of Airshare 300 departed the Dillant/Hopkins Airport (KEEN) in Keene, New Hampshire on Friday, March 3 at 3:35 pm EST and was headed to Leesburg Executive Airport (KJYO) when it had to divert to Bradley International Airport (KBDL). News reports suggested that it was due to severe turbulence, but that is still unknown and highly unlikely. There has been some speculation that it could also be due to a pitch trim issue. The NTSB is investigating the incident and will issue a preliminary report in two to three weeks.
Based on the LiveATC recordings they checked in with Boston Center passing 16,000 ft climbing to FL230. Shortly after, Boston Center cleared them to continue the climb to FL320. A little over two minutes later, Boston Center asked them "how was your ride in the climb?" They didn't respond immediately, but here is the following communication between ATC and the pilot...
Airshare 300 - "Yeah, we need to descend"
Boston Center - "You need to descend?"
Airshare 300 - "Yeah, we need to descend and, and we need to go to an airport."
Boston Center - "Okay, do you know where you need to go?"
Airshare 300 - "No, we need to go to an airport that has medical facilities close by."
Boston Center - "You are pretty much over Barnes...you got Bradley 12 o'clock and about 20 miles if you'd like to go there."
Airshare 300 - "How about Bradley?"
Boston Center - "All right, we can do that. Descend and maintain FL240."
Airshare 300 - "Descend and maintain FL240, Airshare 300."
Boston Center - "Airshare 300 I am going to get you on a vector to get you headed that way, fly heading 150."
Airshare 300 - "Fly heading 150, Airshare 300."
Boston Center - "Airshare 300, what is the nature of the emergency?"
Airshare 300 - "A passenger has a laceration."
They got handed off to another Boston Center sector and then handed off to Bradley Approach. The remainder of the conversation was unremarkable. They didn't declare an emergency and landed at Bradley with no mention of the reason for the passenger's laceration. It is very odd that the pilot would not have mentioned turbulence to the controller as the reason for the passenger injury.
The flight took place on the downwind side of a ridge axis as shown below by the blue line on this 500 mb constant pressure chart valid at 2100Z. A very potent negative-tilted shortwave trough was moving out of the Midwest/Ohio Valley at this time. There were no significant returns in the area to warrant any kind of convective threat and there wasn't a pilot weather report filed. However, on Twitter, the NTSB stated, "NTSB is investigating the March 3 turbulence event involving a Bombardier Challenger 300 airplane that diverted to Windsor Locks, Connecticut and resulted in fatal injuries to a passenger."
The satellite and radar imagery at the time of the incident was unremarkable. For this particular case, the best information can be found on the Skew-T log (p) diagram. Using the 18Z radiosonde observation (RAOB) out of the Albany, New York NWS forecast office (KALY) this appears to have a remote signature of Kelvin-Helmholtz (K-H) instability if this was indeed related to turbulence. Below about 21,000 feet MSL, the lower troposphere was incredibly stable as shown below. The overall lapse rate was about 1.0°C/1,000 feet between 2,500 feet and 21,000 feet MSL.
However, notice the layer from 21,000 feet to 24,000 feet MSL. The air is nearly dry adiabatic or 3°C/1,000 feet which is very unstable with an increase in wind speed in this layer of about 30 knots. Above 24,000 feet MSL, the atmosphere tends to be closer to the standard lapse rate creating stability. It's hard to say for sure given that the RAOB from Albany is not in the exact location and is several hours prior to the incident. We will need to wait for the NTSB to do their investigation to be sure of what may have occurred and if weather is to blame. None of the weather guidance is a clear "smoking gun" that this incident was directly related to weather, much less severe or extreme turbulence.
If you want to learn more about the Skew-T diagram, you can order your copy of The Skew-T log (p) and Me: A Primer for Pilots that is available in both softcover and eBook format.
Most pilots are weatherwise, but some are otherwise™
Dr. Scott Dennstaedt
Weather Systems Engineer
CFI & former NWS meteorologist