Recognizing You‘re In Trouble

An airline transport pilot told NASA's Aviation Safety Reporting System about falling behind due to fatigue: "At arrival time, I had been awake for almost 20 hours and had been on duty for just under 14 hours. During the descent and approach to our destination...I began to notice that I was experiencing the debilitating effects of fatigue in the form of various small errors. The arrival airport was under IFR conditions and...required a great deal of concentration due to inclement weather and turbulence... [I] experienced spatial disorientation due to the very dark area around the airport, a strong crosswind and effects associated with fatigue."

The pilot of a Cessna Caravan 208A on a Part 135 cargo flight reported that, while descending for a landing, "I entered the clouds at 10,000 feet, and experienced severe [and] then extreme turbulence. [I] was unable to control the aircraft's heading, altitude or navigation. The autopilot disconnected, and I was temporarily disoriented and unable to navigate the aircraft on course. ATC queried me about my status and my heading. I told them I was in ’severe turbulence' and needed a climb back to 12,000 feet. ATC asked me if I was tracking the airway, and I told them the autopilot was ’slow to intercept, but I was working it.' ATC told me I was about 90 degrees off course, and asked me if I needed ’no gyro vectors on course.' I said ’affirmative,' and requested a climb to clear the clouds."

The pilot continued, "The loss of situational awareness, aircraft control and navigation all occurred simultaneously. This was induced by the severe turbulence that I encountered and the disorientation I experienced. I was unable to successfully navigate to the airway... I also feel that fatigue was a factor in this event. The weather locally has been poor for about two months and has affected most of our line pilots on a daily basis. We are just not getting enough rest between critical events!"

The NTSB recently issued a report on a flight in which the pilot faced factors similar to those experienced by the Caravan 208 pilot. Unfortunately, this flight ended in an accident in which the pilot and his passenger were killed. At about 11 p.m. on March 1, 2009, a Diamond DA40 crashed into the Pacific Ocean while its pilot was executing an RNAV/GPS approach to runway 14 at Arcata Airport in Arcata/Eureka, Calif. The pilot was on an IFR flight plan.

The pilot rented the airplane at Plant City, Fla., where he had a half-hour ground check and a one-hour flight check. The pilot stated that his destination was Las Vegas, Nev. The first day, the pilot and passenger overnighted in Huntsville, Ala. The second morning, they departed Huntsville at 7:15. The next stop that investigators could identify was Sedona, Ariz., where the aircraft landed to refuel. At 5:30 p.m., the airplane took off for Palmdale, Calif. The pilot overflew Palmdale, however, and instead landed at Bakersfield at 6:41 p.m. The airplane was refueled before it departed for Arcata at 7:36 p.m.

After departing Bakersfield, the pilot picked up his IFR clearance and was cleared to his filed altitude of 8,000 feet, direct to Arcata. At 8:02 p.m., he contacted Oakland Flight Watch to ask about reports of turbulence he had heard on the radio. The briefer said there were AIRMETs for low-level wind shear and moderate turbulence below 18,000 feet. The briefer informed the pilot he was moving into an area of precipitation, and that Arcata's current conditions were light rain, winds from 150 degrees at 10 knots (gusting to 20 knots), a visibility of nine miles, scattered clouds at 5,000 feet, a broken ceiling at 6,000 feet and an overcast ceiling at 9,500 feet.

The pilot was then handed off to Seattle Center; four minutes later, the controller asked for his altitude. The pilot responded that he was indicating 9,300 feet. The controller reminded him that his assigned altitude was 10,000 feet, and asked if the pilot was "having difficulty." The pilot replied that it was very turbulent, with a lot of "ups and downs" and moderate to severe turbulence. Two minutes later, the controller advised the pilot that other aircraft had reported light to moderate turbulence while on the ILS approach to Arcata. He cleared the pilot to descend to 9,000 feet, and asked if he knew what approach he wanted into Arcata. The pilot replied "negative," and asked what others were flying. The controller said most pilots coming from the south (as he was) were doing the ILS and circling to runway 14. The pilot started to say, "I guess I can," but then stopped mid-sentence and said he'd get back to the controller. The controller then advised that a couple pilots flew the RNAV/GPS approach from the north to runway 14. The pilot responded with, "Yeah, we can do an RNAV/GPS for 14."

The controller cleared the pilot direct to CULDU, spelling out C-U-L-D-U phonetically. The pilot asked the controller to repeat the letters, and the controller obliged, explaining that CULDU was the initial approach fix for the RNAV/GPS approach to runway 14. The pilot then stated that it was "really turbulent right now," and said he'd call later for "that information." About 15 seconds later, the pilot transmitted, "All right, can you repeat that fix again?" The controller said the fix was CULDU, that it was the initial approach fix, and spelled it out again.

There was no response for the next 80 seconds. The pilot then asked the controller to verify that the fix was CULDU. The controller advised the pilot that he was "very close," and that the fix was named CULDU. The controller again spelled it out. The pilot responded, "Okay, I got it this time. Thank you."

The controller reported that radar showed moderate to heavy precipitation over the Arcata area, and advised the pilot that he'd be in it the whole time he was inbound. The controller then repeated that rain intensity was moderate to heavy.

Three minutes later, the controller cleared the pilot to descend and maintain 8,000 feet, and the pilot read back the clearance. The controller told the pilot that 8,000 feet was the IFR minimum altitude and that the pilot could go above it, but to go below "would be bad."

Six minutes later, the pilot was cleared to 7,000 feet; two minutes after that, he was cleared to 6,000 feet. The pilot said that he was going to turn toward the west for weather avoidance and then come back to CULDU. The controller cleared him to descend to 5,000 feet, and two minutes later, reminded the pilot to "maintain at or above 5,000 feet, please." The pilot responded that he was indicating 4,900 feet and was climbing back up.

The pilot was cleared to descend to 4,000 feet, direct to CULDU, and to cross CULDU at or above 4,000 feet, and also was cleared for the RNAV/GPS 14 approach. The pilot read back the clearance, but said "at or below 4,000 feet" instead of "at or above 4,000 feet." The controller corrected the pilot.

After the pilot was established inbound to the airport, the controller advised that radar service was terminated and that he could switch to the Arcata CTAF. The controller continued to monitor the flight, noticing that the airplane had descended to 1,400 feet before reaching the final approach fix, which had a published minimum crossing altitude of 2,100 feet. Over a 12-minute period, the controller attempted contact with the pilot 10 times. The last Mode C radar target from the airplane was recorded about one-tenth mile from the final approach fix, at 300 feet above the ocean surface. The airplane went into the ocean seven miles from the airport.

Investigators noted that the elapsed time between the beginning of the trip, when the pilot arrived at Plant City Airport in Florida, and the impact with the ocean off Arcata was 42 hours. During that 42-hour period, the pilot accumulated about 22 hours and 45 minutes of flying time, and was "on duty" for 30 hours and 45 minutes. The NTSB determined that the probable cause of this accident was the pilot's failure to maintain proper altitude and glide path while executing a night instrument approach. Contributing to the accident was the pilot's fatigue.

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.