Aviation Safety Letter 2/2005

Low Visibility Approach Leads to CFIT

Low Visibilty Approach Leads to CFIT

On September 27, 2003, a PA-31 with one pilot and two passengers on board was on a VFR flight from the Îles-de-la-Madeleine, Que., to Gaspé, Que. While en route to Gaspé, the pilot was informed about weather conditions at his destination, which were a ceiling at 500 ft and visibility of 3/4 mi. in fog. The pilot requested clearance for an instrument approach, which he received at approximately 18:57 Eastern Daylight Time (EDT). A few seconds later, the pilot activated the aircraft radio control of aerodrome lighting (ARCAL) with his microphone button. That was the last radio transmission received from the aircraft. When the aircraft did not arrive at its destination, a search was initiated, and due to an emergency locator transmitter (ELT) malfunction, the wreckage was found only the next day at 10:28 EDT, on a hilltop 1.2 NM northeast of the airport. The aircraft was destroyed and the three occupants were fatally injured. This synopsis is based on the Transportation Safety Board of Canada (TSB) Final Report A03Q0151. All times quoted in this article are EDT.

The aircraft had been chartered to transport one passenger from Gaspé to the Îles-de-la-Madeleine, then return to Gaspé with two passengers. Before departing Gaspé, at approximately 16:12, the pilot visited the NAV CANADA Web site for a weather report. The terminal aerodrome forecast (TAF) for Gaspé issued at 15:30 was as follows: between 16:00 and 04:00, scattered cloud at 800 ft AGL, ceiling at 3 000 ft AGL, visibility over 6 mi.; and temporarily between 20:00 and 04:00, ceiling 800 ft AGL. The cloud and weather chart for the graphic area forecast (GFA), valid from 14:00, indicated the possibility of a ceiling at 200 ft AGL and fog patches, reducing visibility to 1/2 mi. along the shores of the Gulf of St. Lawrence.

The pilot arrived at the Gaspé airport around 16:45, and filed a VFR flight plan for the return trip. The aircraft took off at approximately 17:05 with an anticipated return time of approximately 18:45. The flight to the Îles-de-la-Madeleine was without incident, and the aircraft landed there at approximately 18:00. Twelve minutes later, the aircraft took off for Gaspé with two passengers on board. While the aircraft was en route, the TAF for Gaspé was revised twice; at 18:39 and again at 18:49. These two revisions indicated deteriorating weather conditions compared to the TAF received prior to departure; the initial ceiling forecast of 800 ft AGL dropped to 300 ft AGL, and the forecast for visibility was 1/2 mi. in fog. There is no evidence that the pilot either requested or was advised of these revisions.

The pilot contacted the flight service station (FSS) at Québec at 18:53:32, and was advised that the surface winds were favourable for Runway 11. The pilot advised that he would proceed for Runway 11.

At 18:55:13, the FSS specialist gave the pilot the latest weather observation from Gaspé, which was a special bulletin issued at 18:41. It indicated a ceiling at 500 ft AGL and visibility of 3/4 mi. in fog. Based on this information, the pilot advised that he would proceed for Runway 29, but did not specify the type of approach. At 18:56:07, when he was about 7 NM southeast of Gaspé, the pilot requested clearance for an instrument approach, which he received less than one minute later. At 18:57:20, the pilot pressed his microphone button seven times to switch the aerodrome lights on high. That was the last radio transmission received from the aircraft.

According to the information received, all lights were working normally at the time of the occurrence. Except for the call made when 7 NM southeast, the pilot made no reports during the approach.

The aircraft crashed on the summit of a hill with an elevation of about 300 ft ASL, 1.2 NM northeast of the threshold of Runway 29, and 0.8 NM north of the approach track. The swath cut through the trees by the aircraft extended over a distance of about 100 m. The debris pattern at the crash site indicated a high-speed, low-angle impact. Marks left on one of the speed indicators indicated a speed of 185 mph on impact, which is far greater than the normal approach speed of 110 mph. The flaps were retracted, and the landing gear was not in the down and locked position.

There was no evidence found of any airframe failure, engine or system malfunction prior to or during the flight. The pilot was properly licensed and highly experienced. There was no indication that physiological factors affected the pilot's performance.

Regulations permit the aircraft to conduct instrument flights with passengers on board without a copilot, provided that it is equipped with an autopilot. Examination of the autopilot control console did not reveal whether or not it was in operation prior to or at the time of impact. It was not required to be in operation.

The published minimum descent altitude (MDA) for the Runway 29 back course is established at 440 ft ASL and a visibility of 1 mi. The elevation of the aerodrome is 108 ft ASL. Even if the reported visibility was less than the minimum published for an instrument approach, the regulation did not prohibit the pilot from conducting the approach. With regard to the landing, the existing regulations prohibit the pilot of an aircraft on an instrument approach from continuing the descent below the MDA if they do not establish and maintain the visual reference required to land safely. If the pilot loses the required visual references, they must execute a go-around.

On December 16, 1997, a CL-600 crashed at the Fredericton, N.B., airport while executing a go-around in reduced visibility and low ceiling conditions. The TSB investigation of this accident (report A97H0011) identified 28 other accidents in Canada between January 1, 1984, and June 30, 1998, involving heavy aircraft landing in reduced visibility conditions where these conditions contributed to the accident. This investigation also identified a safety deficiency due to the fact that the existing regulations did not provide sufficient protection against the risk of collision with the terrain when instrument approaches were conducted in reduced visibility conditions. In its report, published on May 20, 1999, the TSB recommended that:

"The Department of Transport reassess Category I approach and landing criteria (re-aligning weather minima with operating requirements) to ensure a level of safety consistent with Category II criteria." (A99-05)

Transport Canada responded to the recommendation in August 1999, indicating that a draft regulation amendment to strengthen the standards applicable to instrument approaches in minimal weather conditions would be submitted without delay to the Canadian Aviation Regulation Advisory Council (CARAC) for comment, with the objective of applying the changes as soon as possible.

On August 12, 1999, a Beech 1900D crashed on approach to the Sept-Îles, Que., airport, when the reported weather conditions indicated a ceiling of 200 ft and a visibility of 1/4 SM. The TSB investigation into this accident (report A99Q0151) identified four other accidents that had occurred with reduced visibility as an underlying factor since recommendation A99-05 had been issued. The TSB report on this accident, published March 14, 2002, included a Board recommendation that:

"The Department of Transport expedite the approach ban regulations prohibiting pilots from conducting approaches in visibility conditions that are not adequate for the approach to be conducted safely." (A02-01)

Transport Canada responded to the recommendation on May 26, 2002, indicating that they had prepared 16 notices of proposed amendment (NPA) to address the issue of a regulatory approach ban related to visibility. The response stated that the NPAs were, at the time, under review by the Department of Justice and that the final version was to be published in the Canada Gazette in June 2002. High priority given to the treatment of draft security regulations following the events of September 11, 2001, increased demand for the services of the Department of Justice and resulted in additional delays.

Analysis - The condition of the engines, the angle of impact, and the condition of the pilot indicate that the pilot maintained control of the aircraft until impact. Consequently, this accident falls into the category of controlled flight into terrain (CFIT).

The TAF received prior to departure from Gaspé gave the pilot reason to believe that he could complete the return trip under VFR. However, the GFA indicated instead the possibility of IFR conditions. A better analysis of the weather conditions by the pilot would have enabled him to anticipate the possible deterioration of weather conditions and to plan the flight according to IFR. The absence of weather condition updates while he was en route to Gaspé contributed to the late realization that the weather conditions at his destination were poor. Since the flight was made at night, it must have been difficult to see the poor conditions before flying into them.

It was only after he was informed by the FSS that the pilot realized that an instrument approach would be necessary. He was about 7 NM from the airport when he received his approach clearance, and it could not be determined if the pilot was able to complete the various tasks associated with preparing for an instrument approach, such as: deciding on the type of approach, getting out the approach plate, familiarizing himself with the plate, tuning in to the instrument landing system (ILS) frequency, activating the ARCAL, making the reports associated with an instrument approach at an uncontrolled aerodrome, and modifying the aircraft configuration for the approach and landing.

While the pilot was qualified for, and had considerable experience in, these sorts of conditions, he had to perform several tasks within a short period. His workload was likely quite high by performing these various tasks during the approach. Since the reported visibility was only 3/4 mi., it is unlikely that the pilot had the visual reference required to continue the descent below the MDA.

The TSB determined that the pilot descended to the MDA without being established on the localizer track, thereby placing himself in a precarious situation with respect to the approach and to obstruction clearance. It further determined that the pilot continued his descent below the MDA without having the visual references required to continue the landing, and he was a victim of CFIT.

The TSB is concerned that the existing regulations still do not provide adequate protection against the risk of ground impact when instrument approaches are conducted in reduced visibility conditions. While the TSB recognizes that the proposed approach ban regulatory initiative should decrease the probability of such accidents, until these proposed regulatory provisions come into force, safety measures will remain inadequate against the risk of CFIT resulting in loss of life.

The approach ban regulations went to the Canada Gazette Part I on November 20, 2004. The consultation period was to end in January 2005, after which time the comments were to be reviewed and final publication would take place. - Ed.

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