10th of October 2020, Soft Ground, Blog #756
After a nearly two-week delay, the crew of a Douglas C-54E prepared to operate a supply flight from Kenai to Yakataga Airstrip, Alaska. The delay had been caused by persistent rain, which had rendered the airstrip unsuitable for larger aircraft.
With the weather finally improving and all preparations completed, the crew started the engines and departed Kenai, setting course for Yakataga.
The flight itself was uneventful. Upon arrival, the crew commenced an approach to Runway 08 in Visual Meteorological Conditions (VMC):
Clouds: None
Visibility: 8 miles
Temperature: 3°C
Dew Point: 3°C
Altimeter: 29.27 inHg
A stabilised approach was flown, and the aircraft touched down on the 4,350-foot (1,325-metre) runway. Almost immediately after landing, the crew realised that the braking action was effectively zero. Despite applying the brakes, there was no noticeable deceleration.
As the aircraft continued along the runway, the braking performance did not improve. Unable to stop within the available landing distance, the aircraft overran the runway at an estimated speed of approximately five knots. During the overrun, the nose landing gear collapsed, causing substantial damage to the forward fuselage.
No system malfunctions had been reported during the flight to Yakataga Airport.
The National Transportation Safety Board (NTSB) was notified, and an investigation was launched. As part of the investigation, the flight crew were interviewed.
The pilot stated that, during a formal briefing with a Federal Aviation Administration (FAA) Flight Service Station (FSS), he and the co-pilot had asked whether there was "anything special going on down there" that they should be aware of. According to the pilot, FSS personnel did not mention any NOTAMs indicating that the runway was closed to heavy aircraft, nor was this information provided when the flight plan was activated.
However, FAA FSS recordings revealed a different sequence of events. During the first conversation, the pilot did not specifically request NOTAM information for the airport. During a second conversation, FSS personnel asked whether the crew required any weather information or NOTAMs. The pilots replied that they did not and stated that they were "all good."
The investigation also revealed that an active NOTAM had been issued stating, in part, that the runway was closed to aircraft weighing more than 5,000 pounds.
In addition, the Airport Chart Supplement contained the following remark:
"Runway extremely soft when wet. Use of heavy aircraft over 4,000 lbs gross is not recommended during fall, winter, and spring due to soft field conditions and rutting."
The aircraft's reported landing weight was approximately 62,568 pounds, well above both published limitations.
Following its investigation, the NTSB determined that the probable cause of the accident was:
"The pilot's decision to land on a wet, soft runway, which resulted in the loss of braking action upon landing and a subsequent runway overrun and nose landing gear collapse."
This accident serves as a reminder of the importance of obtaining and reviewing all available operational information before flight, including NOTAMs and airport-specific warnings. Even when weather conditions appear favourable, overlooked information can significantly affect the safety of a flight.
The NTSB investigation report on which this blog is based can be accessed by clicking the PDF file below.
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