NTSB‘s Report Of Fiery Charleston Crash Seems To Omit Key Point: Why?

The Shorts SD3-30, a multi-engine high-wing turboprop-powered commercial utility plane, was landing on Runway 5 at Charleston Yeager International Airport (KCRW) at about 6:51 a.m. at the end of a Part 135 scheduled cargo flight from Louisville International Airport, Louisville, Kentucky. Evidence indicated the airplane impacted the Runway 5 centerline with a 22-degrees left bank and in a 5-degrees nose down attitude. The left wingtip hit the pavement first. Then the left main landing gear hit, and so did the left propeller. The fuselage hit, and the left wing broke off. The airplane slid off the runway and went down a hill. The wreckage came to rest 85 feet below runway elevation and about 380 feet left of the runway centerline. The cockpit was crushed, and there was other severe damage. The captain and first officer, who were the only occupants, were killed.

The NTSB said that the probable cause of the accident was the flight crew's improper decision to conduct a circling approach contrary to the operator's standard operating procedures (SOP) and the captain's excessive descent rate and maneuvering during the approach, which led to inadvertent, uncontrolled contact with the ground. Contributing to the accident was the operator's lack of a formal safety and oversight program to address hazards and compliance with SOPs, and to monitor pilots with previous performance issues.

Documents for the accident flight showed that the airplane had taken off from Louisville with 3,874 pounds of cargo on board, and its takeoff weight was 21,435 pounds, well below its maximum takeoff weight of 22,900 pounds and maximum landing weight of 22,600 pounds. Two Pratt & Whitney Canada PT6A engines drove the five-blade props. The airplane had been manufactured in 1979 as a passenger aircraft capable of carrying 30 people. In 1998, AAC purchased it and converted it for cargo.

The flight left Louisville at about 5:41 a.m. It was on an IFR flight plan and cruised at 9,000 feet. At about 6:37, the first officer radioed the KCRW approach controller, who gave her the current altimeter setting and told her to expect the localizer approach to Runway 5. In response, the first officer requested the VOR-A circling approach, which has much higher minimums, and the controller approved it. The controller cleared the flight to the first waypoint and to descend from 9,000 feet to 4,000 feet. The airplane was about 38 miles west of the airport.

At about 6:42, the controller advised the flight that it was 12 miles from the Charleston VOR/DME (HQV), said to cross HQV at or above 3,000 feet and cleared the flight for the VOR-A approach to Runway 5. The first officer acknowledged. About three minutes later, the controller told the first officer to contact the KCRW tower controller. She confirmed the instruction and switched over to the tower frequency.

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When she checked in with the tower, she at first said that the airplane was on a visual approach, then corrected it to a VOR-A approach. The controller advised her that the wind was from 200 degrees at 5 knots and cleared her to land. About 55 seconds later, the airplane crossed the HQV VOR at 2,900 feet. A study of radar returns by investigators showed that the airplane was descending at between 1,300 and 2,000 feet per minute (fpm).  It continued the descent, and at 6:47:29, it was about 11 miles from the runway and had descended to 2,200 feet.

A low-altitude alarm went off in the tower, and the controller issued an alert to the flightcrew. The controller later told investigators that he believed the alert may have been triggered by the airplane's descent rate. After receiving the alert, the first officer radioed that they were showing 2,200 feet and were descending to 1,600 feet, which was the appropriate altitude after they crossed the second waypoint on the approach known as FOGAG.  

While the airport's ATIS had been reporting wind from 080 degrees at 11 knots, 10 miles visibility, scattered clouds at 700 feet AGL and a broken ceiling at 1,300 feet AGL, the airport's ASOS (Automated Surface Observing System) reported that between 6:25 and 6:30, the ceiling dropped to 500 feet AGL. A human weather observer updated the automated observation to include a few clouds at 100 feet and valley fog. Although the ASOS update was sent to the tower controller, he didn't update the ATIS and didn't radio the new observation to flight 1260.  

At 6:48:25, the airplane reached 1,600 feet and leveled there, but it did so 2 miles before reaching FOGAG. At 6:50:18, the airplane was about one-half mile west of the displaced threshold of Runway 5, traveling at an airspeed of 124 knots, and began to descend at a rate of 2,500 fpm. Company guidance calls for pilots on approach to maintain a constant rate of descent of about 500 fpm. Security cameras showed the airplane come out of the cloud bases, and a witness saw the plane skimming along just below the bases.

The investigation found that the airplane crossed over the Runway 5 centerline in a left bank of up to 42 degrees, apparently in a maneuver designed to line up with the runway. Just before impact, the descent rate decreased to about 600 fpm. A performance analysis showed that the airplane's nose began to pitch up just before impact, which the Safety Board suggested might indicate that the pilot was pulling up as the airplane neared the surface. "However, it was too late to save the approach," the NTSB said. The runway, 6,802 feet long and 150 feet wide, had a displaced threshold 578 feet from the approach end. Evidence showed that the engines had been pulled back to flight idle, and the propellers were rotating at about 1,400 rpm.

When the airplane was converted for cargo use, the cockpit voice recorder (CVR) was removed. If investigators had a recording of what the pilots had been saying to each other, it might have helped explain what was going on and why they were flying a more demanding circling approach rather than a comparatively straightforward localizer approach, which was available. The CVR might have revealed whether the approach had been briefed and, when the captain was doing last-minute maneuvering, whether the first officer was speaking up and calling for a missed approach.

What the Safety Board was able to do was second-guess based on available flight data and what investigators were able to find out about the background of the pilots. The 47-year-old captain held an ATP certificate issued July 25, 2016. His first-class medical certificate was current and required glasses for near vision. He had 4,386 hours, with 1,094 hours in SD3-30 aircraft, 578 of which were as an SD3-30 pilot-in-command. When investigators went through the files the FAA had on him, nothing came up about him having been involved in accidents or incidents. However, they did find that when he took his ATP check ride, he received a notice of disapproval. The reason was excessive deflection of both the glideslope and localizer during an ILS approach, the triggering of glideslope and sink rate warnings from the aircraft's ground proximity warning system, and his failure to execute a missed approach. Three days later, he retook the check ride and passed.

Investigators looked at FAA tracking data for three flights on which he was captain between January and April 2017. He had flown VOR-A approaches to KCRW on those flights. On all three, the data showed that the airplane descended below the minimum descent altitude (MDA) while still in instrument conditions.

The NTSB's investigators found out from a friend of the accident flight's first officer that she had previously expressed concerns about the captain's flying abilities. On one occasion, she sent a text message to the friend complaining that he flew at low altitude in hilly terrain while trying to resolve a landing gear problem. According to the NTSB's report, during a phone call, the first officer told the friend that the captain had difficulty holding heading, speed and course while on instruments. Also, the friend told the NTSB that she reported the captain once lost situational awareness while they were on an instrument approach and almost hit a mountain.

The Safety Board said that it couldn't find evidence to indicate why the captain decided to continue with the approach rather than calling it off and trying again or trying a different type of approach. However, it did speculate that his instrument flying skills were marginal, and he may have felt more comfortable trying to salvage an unstabilized approach taking place under the clouds than climbing back up and having to go back into instrument meteorological conditions. It didn't speculate whether he might have been feeling self-induced pressure to meet the cargo delivery schedule.

The Safety Board also speculated that the first officer wasn't in the habit of speaking up when the captain displayed poor judgment or inadequate flying skills. "The difference in experience between the captain and first officer likely created a barrier to communication due to authority gradient," the NTSB said. Clearly, the first officer had less experience and a lower rank than did the captain, but principles of CRM, crew resource management, are supposed to help overcome that. The first officer held a commercial certificate for multi-engine land and instruments, and second-in-command privileges for SD3-30 aircraft. Her first-class medical certificate was current. She had 652 flight hours, of which 333 were as second-in-command on SD3-30s. 

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The NTSB said that at the time of the accident, Air Cargo Carriers didn't have a formal safety and oversight program to help track whether its pilots were complying with standard operating procedures and also monitor the performance of pilots who had a record of some sort of past performance difficulty. The company had crews based at 12 airports in the U.S. and Puerto Rico and a total of 38 pilots. There were 103 employees and a fleet of 18 Shorts airplanes, two SD3-30s and 16 SD3-60s, a larger version of the SD3-30.

Had the captain elected to fly the localizer approach rather than the VOR-A circling approach, it would have kept them in the air longer in order to line up to intercept the localizer. Their flight path toward KCRW allowed them to slip onto the circling approach sooner. By not opting for the localizer approach, the captain was violating company procedure. On the localizer approach, the MDA was 373 feet AGL, less than half the 773 feet AGL MDA for the circling approach. With the cloud bases at 500 feet AGL, the flight would've popped out above the MDA on the localizer approach, which was not the case for the VOR-A approach. The Safety Board also pointed out that the captain "descended 120 feet below the prescribed minimum stepdown altitude of 1,720 feet two miles prior to the FOGAG waypoint." 

So, what motivated the captain to make the decisions he did? Without knowing what he was thinking, we can't know what we shouldn't be thinking on our next flight. Was he just uncomfortable with being in actual instrument conditions in general? Or was his personality type undisciplined and anti-authoritarian, perhaps, a man who enjoyed excessive maneuvering and the thrill of last-minute dramatic moves? Was the crew's training in CRM insufficient?

Or it could it have been another factor, one the Safety Board left out of its findings of probable cause: Would the approach selection have been different if the controller had passed along the new weather observation indicating that the ceiling was down to 500 feet? The lack of that information didn't force the captain to descend below minimums for the approach. But it's hard not to wonder if that information alone would've made the difference between what would've been an unremarkable arrival and the disaster that became the focus of this NTSB report. PP

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, visit www.ntsbreporter.us or write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.