Probable Cause #33: Fatigued On Final

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This article originally appeared in IFR Refresher, Apr. 2006.

Probable Cause

What any pilot does not need at the end of a long day is low ceilings and poor visibility with fog. Yet, that is what a Beech Baron pilot faced in the early hours of an October morning in 2001 when he needed to reposition his airplane from DuPage Airport (KDPA) in west Chicago to Iowa's Dubuque Regional Airport (KDBQ).

For the 52-year-old pilot, it had indeed been a long day. As a Part 135 pilot for a cargo operator, he had reported for duty in Festus, Mo., at 2 p.m. the day before, following a day off. He then flew seven separate legs -- including a stop in KDBQ -- all under Part 135, before landing at KDPA at 4:05 a.m. the following morning. All that remained was to ferry the airplane, empty and under Part 91, to KDBQ. Surely anticipating the end of a long day, the pilot took off for Dubuque a half hour later.

Weather Or Not

Beech Baron

The NTSB report indicates that the pilot received a weather briefing from a Flight Service Station via telephone prior to the flight. The report doesn't elaborate on the information the pilot received, but the weather at Dubuque at 4:07 a.m. was reported as winds from 330 degrees at 5 kts, a visibility of 1/4 mile with fog, clouds at 100 feet that were broken and 500 feet overcast, and a temperature/dewpoint of 11 C with no spread. A little more than an hour later, and just minutes before the accident, the weather had remained practically unchanged.

To make things worse, the glideslope to the ILS Runway 31 was NOTAMed out of service. (It has since been converted to a localizer-only approach.)

At 5:06 a.m. the pilot checked in with the Chicago Center controller responsible for the Dubuque area, saying he was flying at 4,000 feet. The controller asked the pilot whether he had the Dubuque weather and what approach he wanted to fly. The pilot responded that he had the weather and that he would like the "31 ILS, negative glideslope, localizer approach to Dubuque." Based on this transmission, it's clear that the pilot either knew about the lack of a glideslope from a previous weather briefing or that he had been given the current NOTAMs just before he departed KDPA.

At 5:12 a.m. the controller established radar contact with the Baron and told the pilot to fly a heading of 260 degrees for vectors to the localizer for Runway 31. A few minutes later, the controller informed the pilot that he was seven miles southeast of the outer marker and instructed him to fly a heading of 280 degrees and to maintain 3,300 feet until he was established. He then cleared the pilot for the approach.

At 5:18 a.m. the controller advised the Baron pilot that radar service was terminated and that he could cancel his IFR on the current frequency in the air or on the ground. He was instructed to change to the advisory frequency.

The Dubuque control tower was closed at that time in the morning, but a controller had come in to work early and had started the radio recorders. At 5:19 a.m. the pilot reported that he was 7.5 miles from the airport and was inbound on the Runway 31 localizer. No further transmissions were received from the aircraft.

Look and See?

Dubuque (KDBQ) LOC Runway 31 chart. This is similar to the approach flown by the aircraft in this article. (Click here for larger version - 90 KB.)

The airplane crashed 1.25 miles southeast of the Dubuque Airport at approximately 5:22 a.m. The pilot was killed in the crash when the aircraft impacted trees and an embankment on the side of a county road. Because of the foggy conditions, the airplane was not located until 7:11 a.m. The elevation of the crash site was 1,100 feet.

The airplane struck a stand of trees about 25 feet above the ground and then the road embankment that was located about 166 feet from the initial impact. The heading from the trees to the embankment was 320 degrees.

One witness reported to local police that he had driven by the scene at 6:40 a.m. and that it was very foggy. He saw debris in the roadway and thought it was from a tree that had fallen down. He stopped at the next farmhouse and was going to report a tree in the roadway, but there were no lights on and it appeared that no one was home. He continued on his way but when he heard about the accident on the radio, he returned to make his report.

One of the responding police officers reported that while en route to the scene, "fog conditions were very much present," adding that visibility ranged from 50 to 100 feet at times.

A review of the Localizer Runway 31 approach plate shows an inbound track to the runway of 312 degrees. A pilot is to maintain 3,100 feet until the final approach fix of ZILOM, a locator outer marker. Once past ZILOM, the pilot may descend to 1,540 feet, which is 478 feet above the touchdown zone elevation (TDZE). An ADF or DME is required for this approach in order to identify ZILOM and with the glideslope out, it was necessary to time the approach from the final approach fix.

The pilot held an Airline Transport Pilot certificate for multiengine land aircraft and he had a valid first class medical. His employer reported to the NTSB that he had about 15,000 hours total flying time, 2,000 hours in make and model and that he had logged 88 hours in a Baron in the 90 days preceding the accident. He also had 2,400 hours of night flying and about 800 hours of flight in actual instrument conditions.

For the official cause, the NTSB could find nothing mechanically wrong with the airplane and eventually determined that the "pilot continued flight into known adverse weather and disregarded the minimum descent altitude. Additional factors were the conditions conducive to pilot fatigue, fog, and night."

Fatigue Factor

Let's examine what may have happened to cause the Baron to crash so close to the airport. Keep in mind that we don't know what really happened, and the NTSB report doesn't help us with any information regarding what the pilot may have done differently. Still, the report includes enough food for thought from which we can learn and hopefully prevent a similar accident from occurring again.

The biggest red flag that's immediately obvious is the issue of duty time and fatigue. The pilot reported for work at 2 p.m. on Oct. 22 -- the day prior to the accident -- for his first leg from Festus, Mo., to Dubuque. He departed Festus at 2:30 p.m. and landed at Dubuque at 4:04 p.m. Ten minutes later he departed KDBQ for Davenport, Iowa, where he arrived at 4:37 p.m. Seven minutes later, he was back in the air on his way to Cedar Rapids, Iowa. He landed there at 5:10 p.m.

He was on the ground at Cedar Rapids for an hour and seven minutes. He departed at 6:17 p.m. for Chicago's Midway airport where he arrived at 7:23 p.m. At 7:47 p.m. he departed Midway and landed at Indianapolis at 8:58 p.m. At 9:45 p.m. he departed Indianapolis for St. Louis, arriving there at 11:04 p.m. In St. Louis, after being on duty for approximately 9 hours, he got a break. He was on the ground until 2:55 a.m., or nearly four hours.

That would have been enough time to get something to eat, check the weather for the next leg and perhaps catch a nap. But was it enough of a break?

Sometimes a one- or two-hour nap is worse than no sleep at all, especially if it occurs during the hours you normally would be sleeping. Waking up after a couple of hours of rest when you normally would sleep through the night may leave you more tired than you would have otherwise been.

After the four-hour break, the pilot departed St. Louis for Chicago's DuPage Airport, landing there at 4:05 a.m. Thirty minutes later he was back in the air for the last leg of the trip to Dubuque, where the accident happened. At the time of the accident, the pilot had logged 8.1 hours of flying since he left Festus the day before.

NTSB investigators looked at the Baron pilot's schedule for the days prior to the accident and found that on Oct. 19 he had a day off, on Oct. 20 he worked 16.1 hours with only 4.3 hours of flight time, and on Oct. 21 he was off again.

One problem with those who work similar schedules is that even on days off there are family issues and activities that are likely to take place during the day, which scrambles the pilot's sleep schedule even when he is not working. We don't know enough about the Baron pilot's other activities to know how much rest he got on his days off.

At the time of the accident, the pilot had been on duty for approximately 15.4 hours, so there was a definite fatigue factor in play.

Foggy Airport

Investigators were able to retrieve the pilot's kneeboard, on which he had written the Dubuque weather, including a 0956Z (4:56 a.m. local) timestamp. The written notes showed the visibility at 1/4 mile with few clouds at 100 feet and on overcast layer at 500 feet.

Had the flight been conducted under Part 135, the pilot would not have been allowed to attempt the approach because the visibility was below minimums. Under Part 91, however, he could fly the approach and "take a look," so to speak.

The pilot may have felt that the weather was "within reason" when he left KDPA, even if the visibility was low. Perhaps with a few clouds at 100 feet and the 500-foot ceiling, he may have thought he had a chance to make the landing at DBQ even though no glideslope was available. But upon arrival and finding that the ceiling was now variable at 100 feet and the visibility was still 1/4 mile, the pilot should have decided there was no point in flying the approach at all.

The accident occurred because the pilot allowed the aircraft to descend below the 1,540-foot minimum descent altitude (MDA). The touchdown zone elevation for Runway 31 is 1062 feet and the crash site elevation was 1,100 feet. Did he descend intentionally below MDA or was he so intent on looking out the window for the runway environment that he didn't pay enough attention to the altimeter?

If there was an autopilot on board, did he let it fly the approach? With no glideslope available, that would have required that he manually fly the pitch mode and stop the aircraft's descent at MDA. Once he set up his rate of descent he may have been looking out the window for the runway environment and because of his fatigued state he didn't check the altimeter and allowed the airplane to fly into the ground.

It appears that Dubuque was an airport that he flew into often, and perhaps he felt he was familiar enough with the surroundings that he could safely test the minimums. The crash site was in direct alignment with the runway. Alas, we'll never know the answer to these questions.

Know Your Limits

So, what can we learn from this accident? First, there are no requirements under Part 91 regarding flight or duty time so it is up to each pilot to know what his limits are and to be certain to operate within them. Those limits may need to be adjusted for events that occur, such as weather unexpectedly going down to IFR limits.

While the effects of fatigue can and do make their impact on a single pilot flying in VFR conditions, flying an instrument approach in poor weather conditions requires a great deal of concentration. A fatigued pilot may be slow to react to stimuli, or in some cases he may fail to react when required.

When low IFR conditions occur and there is no close-in alternate that is forecast to meet or exceed your personal limitations, stay on the ground until the weather improves. You can't crash an airplane that is sitting on the ramp outside the FBO while you are waiting for the weather to get better.

Don't be fooled by temporary improvements, either. If the weather shows signs of improving, wait long enough to determine that the improvement will continue and that it is not simply the beginning of intermittent low conditions that will still have an impact on the approach at the end of the flight.

Above all, don't fly when conditions are ripe for fatigue in the cockpit. If you have had a long working day and are scheduled to go home after the meetings are over, stay overnight if you are not up to the task at hand. Over the years I've known too many pilots who had the "go no matter what" mentality. Most of them are no longer with us.


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