Gremline Flight Safety Report: Controlled Flight Into Terrain - Jodel DR1050 & Robinson R44

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Controlled Flight Into Terrain (CFIT) – Introduction

 Human error is the major cause of UK general aviation accidents. Controlled Flight Into Terrain (CFIT) is a major cause of UK general aviation fatal accidents. CFIT accidents are a classic example of human error by the pilot concerned. In this issue we examine two CFIT accidents in an attempt to find some common factors and to alert both fixed-wing and rotary-wing pilots to the hazards that lead to these avoidable fatalities.

 

Controlled Flight Into Terrain accidents may appear to be the most avoidable of all fatal accidents. Yet they continue to happen, causing untold loss to the families of those who die and a feeling approaching helplessness among those who try to prevent aircraft accidents.

       In a future issue of Gremline we will look at an accident that came about through flying up a valley below an overcast sky. The valley narrowed and the valley floor climbed towards the cloudbase that was below the tops of the surrounding mountains. Why would two qualified pilots, both with current instrument flying qualifications, continue on a track that took them directly into the vertical face of a cloud-covered mountain? Loss of situational awareness? Navigation error? Lack of appropriate and positive action in deteriorating weather? “It’ll get better in a few more minutes”? “We can climb out/turn around if it doesn’t get better soon.”? Perhaps some or all of these factors apply, but CFIT accidents do not only result from descending through cloud, or holes in the cloud, into the ground. A common factor in CFIT accidents to GA aircraft is the human attribute described as ‘press-onitis.’ A pilot becomes determined to press-on towards his destination despite deteriorating weather, probably in the hope that either the weather will improve or else he can scrape home below the cloudbase in marginal visibility.

 

 

These accidents often occur at weekends when the pilot is faced with some inconvenience if he returns to his point of departure or accepts the need for a diversion en route to his destination. Remember the old joke about “Cheer up! Things could be worse.” “So I did, and they were.” In this context we will look at an accident where the pilot and his wife paid with their lives for pressing-on towards their destination in deteriorating weather after a weekend flight.

      A light helicopter with a pilot not equipped for instrument flying seems to me to offer the option of a precautionary landing almost anywhere, assuming the pilot has chosen a sensible route away from heavily built-up areas.

      In this issue we examine the probable causal links between spatial disorientation and one, and possibly two, CFIT accidents. Spatial Disorientation was discussed in broad terms in the May 2008 issue of Gremline but is a wide subject that merits study by all pilots. Spatial disorientation contributes to more aircraft accidents than any other physiological problem. Knowledge of the triggers for spatial disorientation and methods to overcome its onset can greatly increase the safety of all flight operations.
      Some accidents are forgivable in that a pilot, through no fault of his own, is faced with a sudden and unforeseen situation that is simply beyond his skill to handle. Most accidents are the result of a chain of circumstances that combine in a cumulative manner to overwhelm the skill and experience levels of a pilot who probably flies fewer hours per year than are required to keep him fully current in the many skills involved in flying any type of aircraft.
      In my opinion, the vast majority of CFIT accidents are totally unforgivable in that the pilot knowingly pushed his luck and flew his aircraft beyond the boundaries of his own skill and experience. As mentioned above, CFIT accidents are often the result of ‘pressing on’ into deteriorating weather instead of recognising the need for a diversion, a precautionary landing or a simple 180 degree turn back to the departure point to wait for another day.

      In the past some UK GA pilots may have hesitated to make a timely diversion to a nearby airfield when the weather began to close in because they feared a huge bill for landing fees when they arrived at their diversion. Thanks to the efforts of Charles Strasser of AOPA this is no longer a consideration in Britain as the vast majority of UK civil, and ALL military, airfields have agreed not to charge GA pilots for a genuine diversionary landing. (Our tables of UK Emergency Diversion Airfields were last updated in October 2008). Pilots in the southern parts of England can never be very far away from a suitable and free diversionary airfield. Those in remoter parts of the UK are more likely to be a considerable distance from any airfield, so their flight requires even more careful planning when thinking of available ‘bolt holes.’ Standards of weather forecasting have made huge advances in the last 20 years or so and accurate weather information is readily available from many sources. There is no excuse for getting into the air without having an accurate and up-to-date weather picture in your mind, with a copy in your hand.
      The commonest scenario leading to a CFIT fatality is where the pilot blunders into deteriorating weather and continues to try to reach his destination until he either loses control in cloud or smashes into the ground in bad visibility.

 

 

A Weekend Trip to Disaster — Jodel DR1050

A Jodel DR1050 owned by a syndicate of which the pilot was a member was operated from Inverness Airport. He held a PPL without any instrument qualification or training. His total experience amounted to 216 hours with 126 hours on type accumulated over a period of seven years, an average of 18 hours per year. He had flown 4 hours in the last 90 days and 1 hour in the last 28 days.

 

He and his wife flew from Inverness to Dornoch on a Sunday in May to take some friends on local sight-seeing flights. The flight from Inverness to the unlicensed grass airfield at Dornoch took twenty minutes at 2000 feet, with the pilot having to find a break in the cloud before landing at Dornoch. The first sight-seeing flight was flown below cloud at about 400 feet agl. The passenger on the second similar flight recalled that the aircraft stall warning light had illuminated during a turn but the pilot appeared unconcerned. Syndicate members were aware that the stall warning tended to operate well above stalling speed.
      The pilot completed pre-flight external checks before he and his wife entered the aircraft for the return flight to Inverness. They were seen to fasten their lap and diagonal seat belts before departing at 15.12 hrs.
      The actual weather at Inverness Airport timed at 14.50 hrs gave a surface wind of 040/07 kt varying between 010 and 080 degrees, visibility of 8,000 metres in light rain showers with few clouds at 400 feet, scattered at 2,500 feet and broken at 4,500 feet. The visibility had dropped to 5,000 metres with scattered cloud at 400 feet by 15.20 hrs. A special observation at 15.28 hrs recorded few clouds forming at 100 feet above the surface.
      The pilot contacted Inverness Tower at 15.20 hrs to report passing Tain (an inactive Danger Area), VFR inbound for Inverness. He was instructed to continue VFR to report field in sight and was passed the weather and airfield details. At 15.25 hrs the Inverness controller advised the Jodel pilot of a very low cloudbase at Fort George and the Beauly Firth, to the west of Inverness. The pilot replied that he was at the Nigg oil rig fabrication yard 1nm north of Cromarty and still VFR with a cloudbase of 400 feet. A direct track from there to Inverness Airport would involve crossing the Cromarty Firth, overflying Cromarty town and then crossing ground rising to 512 ft amsl and passing close to the Rosemackie transmitter mast standing 1,074 ft amsl before crossing the Moray Firth.
      At 15.30 hrs the commander of a BAe 146 inbound to Inverness from the west reported for the benefit of the Jodel pilot that there was a break in the low cloud so that the threshold of Runway 06 was visible from Inverness town. There was no response to this or further transmissions.
      A witness in his house in Cromarty town heard the loud sound of an aircraft overflying the town. He went to his garden and saw the Jodel banked steeply to the left circling into the mist. He saw the aircraft circle twice and heard it circle a further three times before it moved away towards the rising ground to the south-west. A second witness heard the aircraft approach his house that stood 1km south-west of the town on higher ground. He saw the aircraft “very very low travelling towards Inverness. It followed the contours of the rising ground dipping its wings to the left before disappearing over the crest of the hill in a wings level attitude at a height half that of the nearby trees.” Some moments the aircraft struck the ground and both occupants suffered fatal injuries.
      The aircraft came to rest inverted on the top of a 340 ft amsl hill. Ground marks indicated that the Jodel had crashed on a heading of 280° M and then rotated through 270° before coming to rest 6 feet further on. The aircraft had been pitched to at least 30° beyond the vertical, turning to the left at a speed of about 60 kt on impact. The engine was at low power. The airbrakes were unlocked and drooped about one inch from the closed position but their position before the crash could not be determined. There was no evidence of any pre-impact failure.
      The AAIB came to the conclusion that the pilot, untrained for instrument flying and attempting to remain VMC, appeared to have become disorientated and crashed into rising ground, perhaps having stalled while attempting to climb through the low cloud.


Summary
The probability is that the Jodel was actually out of control on impact so perhaps it would be more accurate to classify this accident as being caused by Spatial Disorientation. BUT the pilot knowingly flew his aircraft into deteriorating weather until the situation got to the point where he could no longer control his aircraft. Perhaps he could have diverted to a nearby airfield with better weather. Perhaps he could have checked the weather at Inverness before leaving Dornoch. Perhaps he should have delayed the flight from Inverness to Dornoch for another day; but he had the pressure of having arranged to take his friends at Dornoch for their sight seeing flights.

 

 

94 Seconds to Impact — Robinson R44

A Robinson R44, with a crew of two and one passenger, crashed into cloud-covered groundnear Chroley, Lancashire, at 16.45 hours UTC in early February, killing the three people on board. This review of the accident is closely based on AAIB Field Investigation Ref: EW/C2000/02/01 which source is gratefully acknowledged.

 

A Bell 206 helicopter flew two pilots from Coventry to Blackpool to collect the Robinson R44 and return to Coventry where the Robinson R44 was to be used for pilot training. The Bell 206  carried two passengers, one of whom decided to return to Coventry in the Robinson R44 instead of travelling back in the Bell 206. The crew of the R44 consisted of the commander who held a PPL(H) with an Instructor Rating  and another pilot who held a PPL(H) and was converting to the Robinson helicopter. The commander was qualified to instruct on both the R22 and R44 and to fly at night. He had a total of 737 hours with 11 hours on the R44. The other pilot was qualified as pilot-in-command of the Bell 206 and the Robinson R22. He had a total of 88 hours on helicopters with 2 hours on the R44. Neither pilot was trained or qualified to fly by sole reference to flight instruments.
      The commander of the Bell 206, with one passenger, agreed to follow the Robinson R44 in loose formation back to Coventry. The R44 had a more capable navigation system and a more experienced commander. The weather on departure from Blackpool was good with no significant cloud and good visibility. A cold front was moving south through the area with extensive low cloud and reduced visibility in rain to the south of the front, between Blackpool and Coventry. The two helicopters departed Blackpool at 16.33 hrs and contacted Warton Radar two minutes later. They climbed from 700 feet amsl to 1,000 feet amsl once they were south of Warton. The R44 commander confirmed with Warton that he intended to transit the Manchester Low Level Route and then onwards to Coventry. At 16.42 hrs the R44 informed Warton Radar that he was descending to 600 feet to remain clear of cloud. He also said that he intended to follow the M6 motorway to the Low Level Route. At 16.44 hrs he reported his position as just south of Leyland and intended to turn through 180 degrees to remain clear of cloud. The Bell 206 pilot, following the R44 at about 60 yards, saw the R44 turn left and enter cloud. The Bell 206 also turned left but remained clear of cloud and settled on a westerly heading.
      Warton Radar asked the R44 commander if he was happy with his position as he was three miles north west of Winter Hill radio mast that rises to 2452 feet above mean sea level. The R44 commander replied, “We’re actually in the cloud now can you give us some vectors?” The time was 1644:10 hrs. The following transmissions were recorded:


1644:16 Warton to R44: “Head west now make the heading 270. I’ll take you back towards the M6 and you can pick up the M6.”

1644:24 R44 to Warton: “Affirm we are turning right east … was that east to follow the M6?”

1644:30 Warton to R44: “No go west onto heading 270 … can you fly the heading?”

1644:33 R44 to Warton: “Affirm …west turning left onto west 270.”

1645:00 Warton to R44: “Squawk for me 3641.”

1645:04 R44 to Warton: “3641 .. we’re actually in a bit of trouble now .. if you can give us a bit of assistance … we’re climbing to 1500 feet to get out of the cloud.”

1645:27 Warton to R44: “Just confirming I do have you identified you’re 12 miles south east of Warton make the heading 270 to take you back towards the M6.”

1645:42 R44 to Warton: “Helicopter Golf Mike Echo we’re in trouble.”

1645:44 No response to transmissions from Warton Radar.

The pilot of the Bell 206 requested radar vectors to the last recorded position of the Robinson R44 but could not reach the position because the high ground was covered by cloud. He then continued to Coventry. A police helicopter offered assistance and made several attempts to locate the crash site until it was forced by fuel shortage to return to base.

 


Recorded radar data showed the R44 crossed the M6 at Leyland before following the M61 until abeam Chorley where it began a left turn towards high ground, when the pilot reported entering cloud. The speed had been steady at 100 kt until then but increased to 113 kt on entering cloud before reducing to 65 kt over the next minute. It then recovered briefly to 83 kt before reducing again to 67 kt.
      The helicopter hit the ground at a high rate of descent on a track of 060 degrees magnetic. It was pitched slightly nose down and moderately banked to the right with some right sideslip. The groundspeed was of the order of 60 kt. The skids dug into soft ground and the fuselage and lower cabin disrupted. The cabin floor was dragged under the fuselage as the aircraft rolled rapidly forward and onto its right side with the rotor mast and head striking the ground heavily. A 2 metre piece of the outer main rotor blade was thrown 85 metres from impact. The complete instrument binnacle lay 45 metres from the impact point.
      There was no evidence of any pre-impact failure. There was no clear indication of any instrument warning caption light being lit prior to impact, but AAIB considered the evidence to be inconclusive because of the relatively low impact forces involved. All circuit breakers were still set except the attitude indicator circuit breaker which had tripped. It was considered likely that this circuit breaker had popped because of shorting in the wiring harness during the break-up sequence. The attitude indicator was examined in detail and found to be operating correctly without drift in pitch or roll.

Summary
The flight was uneventful until the two helicopters crossed the M6 motorway near Leyland and began to follow the M61 motorway southwards. This was not as planned by the R44 commander and suggests that he may have crossed the M6 without seeing it in the deteriorating visibility and lowering cloudbase. He became unsure of his position and recognised the hazard of continuing southwards so announced his intention of turning through 180 degrees, away from the worsening weather. Unfortunately, he turned left towards high ground. This reinforces the supposition that he had become lost, as a right turn would have taken him away from high ground towards flat country. The R44 then entered the lowering cloud and the commander, not being trained or qualified in instrument flying, realised that he was in a dangerous situation. The R44 instrument panel was fitted with an ASI, VSI, altimeter, magnetic compass and artificial horizon identical to the R22 that was more familiar to the commander. The R44 was also fitted with a Garmin 150 GPS and a Skyforce Tracker that could show the aircraft’s position on a map display. The commander of the R44 was not familiar with the GPS/Tracker equipment and it was not intuitive in its set-up procedure. This equipment was destroyed on impact and nothing could be recovered from the memory. It was not possible to say if the GPS was used during the accident flight. Several 1:250,000 topographical charts covering the intended route were found in the wreckage.
      Radar recorded an erratic flight path during the last minute and a half, suggesting that the pilot had become disorientated and lost control of the helicopter. The commander’s confusion of ‘east’ for ‘west’ may also indicate a high mental workload while he was trying to resolve the disorientation. The pilot did not have the ability or training to recover control before the aircraft struck the cloud-covered high ground.

 


The physiological problem of spatial disorientation is one of many subjects dealt with in “Aviation Medicine” [edited by Ernsting and King and available from our Bookshop]. The very real hazards of spatial disorientation are succinctly summarised as follows: “The ability to maintain control of an aircraft without adequate visual cues is quite short, typically about 60 seconds, even when the aircraft is in straight and level flight at the time vision is lost, and shorter still if the aircraft is in a turn. In such circumstances, loss of control occurs because the non-visual receptors give either inadequate or erroneous information about the position, attitude and motion of the aircraft.”

      A common factor in both these CFIT accidents is that the pilots concerned allowed themselves to go beyond their own abilities and training and to get their aircraft into a situation that was unrecoverable. It is vitally important that all pilots, no matter how experienced, qualified and skilled, should be aware of their own limitations and the limitations of their aircraft. If you have the slightest doubt about anything to do with a planned flight then the best thing to do is to return to your armchair and resolve that doubt before you get into the aircraft.

A superior pilot is one who uses his judgement to avoid having to use his superior skill.

 

 

 

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