On the morning of October 18, 2022, the pilot and other occupant on a Beechcraft King Air 90 (N515GK) were fatally injured in an accident while on approach to Mid-Ohio Valley Regional Airport (KPKB). According to FlightAware (below), the flight departed John Glenn Columbus International Airport (KCMH) at 6:40 a.m. and it was headed to Parkersburg, West Virginia. Local news reported that the crash occurred near Marietta, Ohio around 7:10 a.m. EDT. This news video of the crash shows the aircraft plummeting to Earth in almost a vertical orientation suggesting some sort of loss of control.
The NTSB will be visiting the site and will likely issue their final report in about a year from the date of the accident. There are a lot of potential factors to cause such an accident that may or may not include weather. However, as will be discussed below, serious icing conditions were indeed present in the area and this accident may be associated with an ice contaminated tailplane stall (ICTS). Please understand that this is pure speculation and may not be the cause of this crash.
Update: NTSB preliminary report has been posted. No new important information was provided from a weather perspective. Here is the only information in the report that was dedicated to weather on that morning.
"Preliminary weather information at the time of the accident indicated that there were pilot reports throughout the area for trace to moderate icing conditions and AIRMETs moderate icing. Weather satellite data showed supercooled liquid water clouds from 1,300 ft agl to about 8,000 ft agl."
Kurt Blankenship who is a research pilot and deputy of aircraft operations at the Glenn Research Center in Cleveland has stated that when the tailplane is accreting ice, even a small change to the angle of attack can initiate the stall. Something as simple as changing the power setting can induce this stall. A tailplane stall can be very violent with the controls quite literally snatched from your hands. Often it takes an enormous amount of back pressure on the controls to recover...sometimes even requiring that the copilot assist in this recovery. Kurt suggested that the Twin Otter is especially prone to tailplane stalls.
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According to the FlightAware log, the pilot climbed to the cruising altitude of 11,000 feet MSL after departing Columbus. Given the marginal VFR (MVFR) conditions at Parkersburg, the aircraft was likely vectored to an instrument approach at KPKB. In fact, this audio captured by LiveATC clearly suggests that the pilot checked in as being on the RNAV approach for Runway 21. Furthermore, the routine observation issued at 1053Z reported light southwest winds, 10 statute miles surface visibility with an overcast ceiling of 1,400 feet as shown below.
KPKB 181053Z 26003KT 10SM OVC014 03/01 A2980 RMK AO2 SLP094 T00330006On this particular morning, the freezing level in the area was forecast to be in the range of 1,000 to 3,000 feet MSL based on the 1-hour lowest freezing level forecast below from the Rapid Refresh (RAP) model.
As shown below, a surface cold front was quickly moving to the southeast and was located just to the west-northwest of the Parkersburg airport at 0900Z (5 a.m. EDT) or two hours prior to the accident.
By 1200Z (8 a.m. EDT) or one hour after the accident, the cold front had passed well to the southeast of the route (below) and was located in western Virginia. This means that the entire route was on the cold side of this cold front.
According to Ben Bernstein who is an expert on airframe icing environments, it is not uncommon for a stratocumulus deck to form in the wake such a cold front when cold-air advection destabilizes the boundary layer and subsidence above the front caps the vertical development of these clouds giving them a quilted-like appearance when viewed from above. This is easiest to see on the color infrared satellite image below as a large area of yellow and pale green located just behind the cold front. If you compare the leading edge of the clouds, it almost is coincident with the location of the cold front above.
Magnifying the area around the accident site the bright yellow color equates to a cloud top temperature of roughly -10°C. This implies that the stratocumulus cloud deck is dominated by water in the liquid state.
Moreover, this analysis below from the Rapid Refresh (RAP) model shows a clear stratocumulus signature. This includes a nearly dry adiabatic layer just above the surface with moist instability in the saturated layer between 2,500 feet and 6,000 feet MSL and a capping layer above. The cloud top temperature is a rather warm -8°C at 6,000 feet which is fairly consistent with the IR satellite image above given the 2°C cold bias that often occurs with these images. Lastly, the freezing level is roughly 2,200 feet MSL or 1,300 feet AGL.
This puts the aircraft in icing conditions during a descent from 6,000 feet to as low as 2,500 feet MSL. Based on the FlightAware track log, that's an exposure of approximately 7-8 minutes.
This weather system was producing some rain at Parkersburg as the cold front passed shortly after 0900Z. Notice that in the remarks section in the METAR below, rain began at 20 minutes after the hour (0920Z) and ended at 30 minutes after the hour (0930Z).
KPKB 180953Z AUTO 26008KT 10SM OVC016 03/00 A2979 RMK AO2 RAB20E30 SLP089 P0000 T00330000
Moreover, the cloud depth also increased (ceilings lowered) in the overnight hours leading up to the time of the accident before it reached 1,300 feet at 1153Z and then eventually lifted several hours after the accident. Such a deepening of the clouds provides a better environment for larger drops and possible SLD.
KPKB 181453Z 25006KT 10SM FEW017 FEW022 OVC042 05/01 A2985 RMK AO2
KPKB 181353Z 26006KT 10SM SCT019 OVC042 04/01 A2984 RMK AO2 SLP107
KPKB 181253Z VRB06KT 10SM BKN016 OVC046 04/01 A2982 RMK AO2 SLP102
KPKB 181232Z 26004KT 10SM OVC015 03/01 A2981 RMK AO2 T00330011
KPKB 181153Z VRB03KT 10SM OVC013 03/01 A2981 RMK AO2 SLP097 60000
KPKB 181150Z 26006KT 10SM OVC013 03/01 A2981 RMK AO2
KPKB 181053Z 26003KT 10SM OVC014 03/01 A2980 RMK AO2 SLP094 T00330006
KPKB 180953Z AUTO 26008KT 10SM OVC016 03/00 A2979 RMK AO2 RAB20E30
KPKB 180853Z AUTO VRB05KT 10SM OVC022 04/M01 A2977 RMK AO2 SLP084
KPKB 180753Z AUTO 29006KT 10SM OVC027 04/M02 A2976 RMK AO2 SLP081
KPKB 180733Z AUTO VRB06KT 10SM OVC029 04/M02 A2976 RMK AO2 T00441017
Other nearby observations that morning from Ohio University Airport (KUNI), Cambridge Municipal Airport (KCDI) and Zanesville Municipal Airport (KZZV) included light drizzle (-DZ) and light rain (-RA):
KUNI 181055Z AUTO 25005KT 10SM OVC017 03/02 A2981 RMK AO2 T00280015
KUNI 181035Z AUTO 25006KT 10SM -DZ OVC015 03/02 A2981 RMK AO2
KUNI 181015Z AUTO 26006KT 10SM OVC013 03/01 A2981 RMK AO2 T00300012
KCDI 181115Z AUTO 22004KT 7SM -DZ OVC010 03/02 A2977 RMK AO2
KCDI 181055Z AUTO 21003KT 10SM BKN012 OVC017 03/02 A2977 RMK AO2
KCDI 181035Z AUTO 21004KT 10SM OVC012 03/02 A2977 RMK AO2 T00330020
KZZV 181053Z AUTO 22004KT 10SM BKN010 OVC017 03/02 A2977 RMK AO2 RAE35 CIG 007V014 SLP083 P0000 T00330017
KZZV 180953Z AUTO 23004KT 9SM -RA OVC012 03/02 A2975 RMK AO2 RAB12E21B43 SLP079 P0000 T00330017
KZZV 180853Z AUTO 26008KT 10SM OVC010 03/01 A2974 RMK AO2 SLP075 T00330006 55003
The Current Icing Product (CIP) tends to agree that this is a warm-topped icing scenario as can be seen below by the red area. WMPCP means precipitation other than snow is being observed at surface with a cloud top temperature warmer than -12°C. This largely hints at an SLD event given the warmer cloud tops which imply the cloud was dominated by water in the liquid state plus the time of day when FZDZ aloft tends to be relatively common.
The real smoking gun is the supercooled liquid water (SLW) content in these clouds. CIP identified that the SLW content was over 0.5 grams per cubic meter during the descent which is quite high, but not unusual for a continental stratocumulus cloud deck especially in the tops where the air is the coldest and the SLW content is the highest. Shown below is the SLW content at 6,000 feet MSL at the time of the accident.
The SLW content was still fairly high, but lessened with a lower altitude. Below is the SLW content for 5,000 feet MSL.
And for 4,000 feet MSL.
Given the analysis above, it's reasonable to assume that airframe icing may have played a role in this accident especially if ice accreted behind the protected surface on the tail of the aircraft.
Most pilots are weatherwise, but some are otherwise™
Dr. Scott Dennstaedt
Weather Systems Engineer
Founder, EZWxBrief™
CFI & former NWS meteorologist
