Probable Cause #5: Improper Procedure

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A pilot salvaging an approach ended up in a stall and spin when turning from base to final. Did good IFR conditions cause him to drop his guard? This week's Probable Cause column presents some ideas.

This article originally appeared in IFR Refresher, September 2005.

Probable Cause

What if you knew the ceiling was at 700 feet and the visibility was four miles at your destination airport as you approached it on an IFR flight? It is likely that you would be less concerned about the approach than you would be had the weather report been 200 and 1/2. If that was the case, might you drop your guard a little? Would you be tempted not work as hard to maintain the ILS approach as you might if the weather was worse?

In December 2003 a Beech Bonanza S35 left Adams Field (KLIT) in Little Rock, Ark., for a 45-minute flight to Boone County Airport (KHRO) near Harrison, Ark., a distance of 103 nm. The weather at KLIT was VFR with scattered clouds at 1,500 feet, a broken ceiling at 3,200 feet, and seven miles visibility. The report at KHRO was not as good, with a 700-foot overcast and three miles with mist. The 6,000-hour private, instrument-rated pilot had contacted flight service twice before departure, so he was aware of the weather at KHRO.

The Boone County Airport is located about 50 miles east-northeast of Fayetteville in the northwest corner of the state. The flight is generally an easy one and on the day of the accident the weather was forecast to improve to VFR conditions as the day progressed.

The flight was uneventful. Takeoff from KLIT was at 9:10 a.m. local and the pilot was handed off to Memphis Center about 15 minutes later. All communications with controllers appeared to be normal. Late in the flight, but before the approach sequence began, the Bonanza pilot was advised by a Learjet departing from Harrison that there was a coyote on the right side of the runway, about 1,000 feet from the approach end. In his response to the call, the Bonanza pilot joked about it being "Wiley Coyote."

At 9:54 a.m. the controller asked the pilot if he had received the Harrison weather. The pilot stated that he did. Only a minute before, the Harrison ASOS had reported the weather as 700 overcast, four miles with mist and winds from 300 degrees at seven knots. It's unknown if the pilot had received this latest weather report, which was essentially the same as it was when the pilot departed Little Rock.

KHRO (Harrison) ILS Runway 36 (click for larger view -- 120 Kb)

A couple of minutes later the controller asked if the pilot was picking up BAKKY, the locator/outer marker and initial approach fix for the ILS Runway 36 approach at KHRO. The pilot responded that that he was. The controller then told the pilot to maintain 3,700 feet to BAKKY and cleared him for the approach to Harrison, advising him to cancel on the controller's Center frequency. Shortly thereafter, the controller told the pilot, "Radar contact lost. Change to advisory is approved. Report your cancellation this frequency. You are number one out of three aircraft inbound at this time." The Bonanza pilot acknowledged the frequency change.

Too High

There were numerous witnesses who either heard or saw the aircraft, or heard the pilot make transmissions over the CTAF frequency. At about 10:00 a.m. an airport employee said he heard the pilot report on CTAF that he was over BAKKY and asked if there were any other aircraft in the vicinity. A few moments later the pilot announced that he was "a little high on the approach," and that he was going to circle to make a downwind entry for Runway 36. At 10:06 a.m. the pilot contacted Memphis Center and told the controller that he was on a 1/4-mile final for Runway 36. The controller had no further communications with the pilot nor did he receive any transmissions from the pilot indicating any problems.

One witness who worked at the airport said he first saw the airplane when it was midfield down the runway, about 300 or 400 feet above the ground. The aircraft made its turn to crosswind followed by a turn to downwind. But the downwind turn was early and the aircraft was close in to the runway.

The witness said that while the aircraft was on downwind the aircraft appeared to get "lower and slower than usual." As the aircraft passed over some buildings located southwest of the runway it made a left turn onto the base leg followed by a steep turn to final, overshooting the runway. At this point, the witness had to turn his attention to a customer he was assisting and lost track of the airplane.

About two or three minutes later the witness heard someone on CTAF calling the Bonanza, asking if he was on the ground yet. When there was no response, the person on the radio asked again. When there was still no response, the first witness and another airport employee decided to check the ramp and the incoming taxiway for the Bonanza but they did not see it. They then drove to the approach end of Runway 36 and found the airplane had crashed short of the runway.

Another witness said he saw the airplane flying south at a "real low altitude." It then made a sharp turn to the east (base leg), followed by another to the north. He observed the nose of the airplane as it "shot" up in the air and "pivoted" before heading straight toward the ground.

Two more witnesses, one driving a truck heading west, and the other standing outside of a building just west of the airport, said they observed the aircraft flying southbound at approximately 50 to 60 feet above the ground when it made a "hard" left turn. It then made what one of the witnesses said was a "hard twisting movement" and the nose of the airplane pointed down toward the ground. It disappeared from view and the witness in the truck called 911 and drove to the accident site.

The pilot and his passenger were killed in the accident. The pilot's logbooks were not recovered and his total time and instrument currency could not be confirmed.

Stall/Spin

The NTSB eventually concluded that the cause of the accident was the "pilot's failure to maintain proper airspeed, which resulted in an inadvertent stall. Contributing factors were the pilot's failure to follow the published instrument approach procedures, and his failure [to] attain the proper glidepath."

The reasons for the accident as cited by the NTSB sound plausible and based on the observations from witnesses and our own understanding of aerodynamics, they are probably accurate. While the NTSB is very good at telling us what happened, we are often left to wonder why an accident happened, which is just as important to know if we want to avoid something similar in the future.

It's impossible, and some will say unfair, to try to read the mind of a dead pilot, but lacking mechanical causes for the accident, we have to look at the pilot's attitude or state of mind for possible clues. It's important to keep in mind that these will always be suppositions and assumptions, as there is no way for us to know what the pilot was thinking that day. What we do know is that while the weather was IMC, it wasn't all that bad. We also know the pilot had approximately 6,000 hours of flying experience and we know he had owned the Bonanza for nearly two years. It's reasonable to assume that he should have been thoroughly familiar with the airplane's flying characteristics and the procedures for flying instrument approaches.

But what about mental preparation? When a pilot files an IFR flight plan, he has to be prepared to fly the flight not only in the weather that exists, but in any different weather that may occur and has not been planned for in advance. If the pilot checks the weather and thinks, "That's a piece of cake," he might not be ready for the unusual or unexpected.

Put yourself in the Bonanza pilot's shoes. What would you think if the weather briefer told you that the forecast for your destination was for a minimum of 700 feet and four miles with improving conditions? You might conclude that getting into the destination airport, one that has an ILS approach, is not going to be a problem. It's even possible that you would overlook some important backups, like an IFR alternate. Any instrument pilot who has been around a while who says he has never been lured into this trap of false security is lying.

Along the route the Center controller tells you that he just had an aircraft cancel IFR on the approach to the airport at 1,900 feet. The airport elevation is 1,365 feet MSL, so that means he broke out of the clouds at 535 feet. That information is valuable because it should make you rethink your earlier conclusion. Sure, the ASOS is still calling a ceiling of 700 feet and now the visibility is four miles. That's not so bad. But if the other airplane broke out at 535 feet AGL, then there must be some other clouds in the vicinity that the ASOS is not seeing.

Too Good To Be True

This is exactly the scenario that played itself out for the Bonanza pilot. When the controller told him about the other aircraft and where it broke out on the approach, his response was, "Roger. We'll stay (unintelligible) 1,900." Did that mean that he was going to descend to 1,900 feet and wait for the airport to come into view, or could it have meant something else, given that the words were not intelligible?

On an ILS approach to any runway, the airplane should not be "a little high." Had the pilot flown the approach the way it was intended, the accident would never have happened because he would have landed straight in on Runway 36. But once he made the decision to over-fly the runway and enter the traffic pattern on a downwind leg, it was his responsibility to fly the pattern safely. All of the witness reports put the airplane "low and slow." Exactly how low, we don't know since I doubt he was at 50 feet on downwind as two of the witnesses stated.

Another problem, in addition to flying the pattern too low, was that the pilot didn't allow enough room to make normal turns to the runway. The visibility was good, though there may have been some clouds lower than the reported 700 feet in the area. Could he have been in too much of a hurry to get on the ground once he decided to fly the pattern? The winds were from 300 degrees at seven knots, or 60 degrees off the runway heading. That means it would have been pushing the airplane toward the runway on the downwind and base legs. A 6,000-hour pilot should have realized that as he flew over the runway before making the turn to downwind.

Low, steep, slow turns to final approach are not safe and have killed many others over the years. An acquaintance of mine watched a Cessna 150 stall and spin on the turn from base to final doing the same thing on a beautiful VFR day. He was in his 172 right behind that pilot and his passenger, who were killed. Over the years I have heard about so many accidents of this type that I can't believe any pilot has not been sufficiently warned.

So, the time to call the flight a "piece of cake" is after the airplane is safely on the ground at its destination, not before the flight begins. Even if the weather is clear, there are potential problems that the pilot must be aware of and alert for.

The next time you fly a circling approach or decide to fly the VFR pattern at the end of an instrument approach pay close attention to your altitude and location with regards to the landing runway. Low and slow approaches in the VFR pattern don't hack it and there certainly is no place for them during circling operations out of an instrument approach.


More accident analyses are available in AVweb's Probable Cause Index. And for monthly articles about IFR flying including accident reports like this one, subscribe to AVweb's sister publication, IFR Refresher.