DEPARTMENT OF AIR ACCIDENT INVESTIGATION

Transcription

1 REPUBLIC OF KENYA MINISTRY OF TRANSPORT DEPARTMENT OF AIR ACCIDENT INVESTIGATION P.O. Box Nairobi Telephone: Fax:

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3 CIVIL AIRCRAFT ACCIDENT REPORT CAV/ACC/DPS/06 OPERATOR: DAVID JOHN PENROSE AIRCRAFT: SKYSTAR SERIES 6 REGISTRATION: PLACE: 5Y - DPS WILSON AIRPORT DATE: 5 TH FEBRUARY 2006 TIME: 0416 HOURS All times given in this report are Coordinated Universal Time (UTC). East African Local Time is UTC plus 3 hours.

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5 TABLE OF CONTENTS TABLE OF CONTENTS... 5 SYNOPSIS FACTUAL INFORMATION History of the flight Injuries to persons Damage to aircraft Other damage Personnel information Aircraft information Meteorological information Aids to navigation Communications Aerodrome information Flight recorders Wreckage and impact information Medical and pathological information Fire Survival aspects Tests and research Organizational and management information Additional information New investigation techniques ANALYSIS CONCLUSIONS Findings The pilot requested ATC that he wanted to land immediately The pilot selected Runway The pilot did not say why he was turning back The aircraft had not gained enough altitude to be able to execute a successful turn back Probable cause SAFETY RECOMMENDATIONS... 25

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7 SYNOPSIS The aircraft, registration 5Y-DPS, a Skystar series 6 was on departure for a flight from Wilson Airport to Mweiga Airstrip. The aircraft called Wilson Air Traffic Control (ATC) Tower for taxi and departure clearances. The aircraft had two persons on board and five hours of fuel endurance. The aircraft took off from runway 14 at 0414 hours. It was seen by ATC to rotate shortly before the intersection of the two runways with the initial climb lengthwise the runway before a right turn was made. During the climb, the pilot reported to ATC that he wanted to land immediately on runway 32. At this time, the succeeding aircraft on runway 14 was already lined up and it was advised to immediately leave the runway in order to give way to the accident aircraft. At 0416 hours, the aircraft crashed short of runway 32 at approximately 200 meters from the threshold and on a heading of approximately 060. The probable cause of this accident was the pilot s decision to turn back and land on the same runway from which he had just taken off.

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9 1 FACTUAL INFORMATION 1.1 History of the flight The aircraft, registration 5Y-DPS, a Skystar series 6 was on departure for a flight from Wilson Airport to Mweiga Airstrip. The tape transcript of the conversation with the Tower is reproduced below: 04:11:46 PILOT Wilson tower 5Y DPS Good Morning 04:11:47 TOWER 5Y DPS Morning 04:11:48 PILOT Roger DPS request take-off clearance, taxi for 14, KF6, 02 on board, endurance 0500 hours TOWER PS confirm clear with customs 04:12:00 PILOT Affirm, clear with customs 04:12:07 TOWER Holding position 14 Q 1020 PILOT In inches please TOWER 3012 PILOT 3012 for 14 DPS 04:14:19 PILOT Tower DPS ready to backtrack and hold 14 TOWER DPS line up and wait 04:14:27 PILOT Line up and wait DPS 04:14:52 TOWER 5Y DPS wind is 270/08 you are cleared for take-off PILOT Cleared for take off DPS 04:16:21 PILOT Wilson tower May Day from DPS requesting an immediate on to 32

10 END OF TRANSCRIPT After take-off, the aircraft was seen by Wilson Air Traffic Control (ATC) Tower to rotate shortly before the intersection of the two runways with the initial climb lengthwise the runway before a right turn was made. During the climb, the pilot requested ATC that he wanted to land immediately on runway 32. At this time, the succeeding aircraft on runway 14 was already lined up and it was advised to immediately leave the runway in order to give way to the accident aircraft. At 0416 hours, 5Y DPS crashed short of Runway 32 at approximately 200 meters from the threshold and on a heading of 060. The aircraft slammed into the ground close to a pit latrine in the slum area at the end of Runway 14. It immediately burst into flames killing the two occupants. The aircraft was completely destroyed by the ground impact as well as the post impact fire. Eyewitnesses reported to have seen the aircraft flying low, shortly before it crashed with cracking engine sound. They reported not to have seen any smoke or fire when the aircraft was in the air. They were not able to rescue the aircraft occupants due to the big inferno. The Wilson Airport Fire and Rescue Services trucks arrived at the scene and found the aircraft already consumed by the inferno with no survivors.

11 1.2 Injuries to persons INJURIES CREW PASSENGERS OTHERS TOTAL FATAL SERIOUS MINOR NONE TOTAL Damage to aircraft The aircraft was completely destroyed by the ground impact as well as the post impact fire. 1.4 Other damage The aircraft crashed next to a pit latrine in the slum area at the end of Runway Personnel information The pilot, aged 44, was also the owner of the aircraft. He held a private pilot licence (PPL) number YK-316-PL which was due for renewal on 21 st April He had ratings for the Cessna 172, 182, and 206. He held a second class medical certificate valid up to 21 st April As at 13 th April 2005, his total flying experience was hours. For the 12 months period from 13 th April 2004 to 13 th April 2005, he had flown 26 hours in the Kitfox. He had flown into Wilson Airport the previous day to attend to some social engagements.

12 1.6 Aircraft information The aircraft was a Skystar Kitfox Series 6, serial number S , built by Sylvan Adamson in It had Permit to Fly number 35 valid from 18 th January 2006 to 17 th January It was approved for 2 occupants only with a maximum takeoff weight of 1550 pounds. As at 18 th January 2006, the aircraft had done 72.4 hours since new. The aircraft was fitted with a Rotax 912S engine, serial number / As at 18 th January 2006, the engine had done a total of 72.4 hours since new. The propeller was a composite 3-bladed Warp Drive, serial number T9297, and had also done 72.4 hours since new. The engine and propeller were inspected for renewal of permit to fly on 12 January 2006 and were found satisfactory. The aircraft was last weighed on 24 th June The basic weight of the aircraft was calculated to be 778 pounds. The total moment about the datum (the leading edge of the wing) was inch-pounds. During the flight test for Permit to Fly renewal carried out on 18 th January 2006, the climb speed was 65 miles per hour; the observed rate of climb (OROC) was 352 feet per minute and the stall speed was 45 miles per hour. 1.7 Meteorological information Visibility was good.

13 1.8 Aids to navigation Not applicable. 1.9 Communications Communications were not a factor in the accident Aerodrome information The aircraft crashed at Wilson Airport, 200 meters from Runway 32 threshold. Wilson Airport has two runways, 07/25 and 14/32. The airport has a Control Tower and standard aerodrome equipment. According to the Kenya Aeronautical Information Publication (AIP), the airport s coordinates are S, E. The elevation of the airport is 5300 feet Flight recorders Not applicable Wreckage and impact information The aircraft structure was of tube and fabric construction. Eyewitnesses reported to have seen the aircraft flying low, shortly before it crashed with cracking engine sound. They reported not to have seen any smoke or fire when the aircraft was in the air and they were not able to rescue the aircraft occupants due to the big inferno. The aircraft was completely destroyed by the ground impact as well as the post impact fire. All that remained was the tube structure.

14 The damaged and burnt engine was recovered and stripped. No preaccident defects were detected Medical and pathological information The pilot and the passenger died in the post impact fire Fire The aircraft burst into flames which consumed the aircraft and killed the pilot and the passenger. The fire was fed by the fuel and the fabric used in the aircraft construction Survival aspects The accident was survivable. Eye witness accounts state that the pilot was trying to pull the passenger from the wreckage but they got caught up in the inferno Tests and research The damaged engine was disassembled and inspected. There appeared to be no mechanical defects that would have made it malfunction. The following article, written by Mike Valentine, appeared in the June and July 2004 issues of Australian Ultralights. One of the most persistent accidents in the operation of single-engined aircraft is the socalled turn-back manoeuvre. It is pretty topical at the moment and has received a bit of an airing in this magazine. Maybe its time to take a look at it in a bit more detail. We will do it in two parts, firstly the manoeuvre itself and then the pilot strategies to deal with it.

15 The turn-back is defined as a partial or full failure of the engine, followed by an attempt to turn back to the runway just used for the take-off instead of landing on whatever is available straight ahead, or within about 30 degrees each side of straight ahead. Historically attempts to turn all the way back have resulted in a very low success rate; in fact the turn-back has acquired the reputation of being one of the killer manoeuvres, something that should never be attempted, no matter what. What are the facts? Is the turn-back as dangerous as it is painted? Must it be ruled out at all costs or is there room for maybe attempting it under certain circumstances? Let us examine all the pertinent factors and then you, as pilots, can make up your own minds. The anatomy of the turnback The starting point for this examination is the simple fact that an engine failure should not, of itself, cause a serious or fatal accident. In essence, the problem consists of maintaining the aircraft s energy level following the partial or full loss of power, maintaining a safe speed no matter what other factors are present and keeping the aircraft under full control to enable a safe landing to be carried out. On the face of it, this should not be too difficult a task, but the facts seem to indicate otherwise. The need to maintain a safe speed is paramount. So is avoidance of loading up (applying G loadings, in other words pulling back on the stick) the aircraft. These factors are not hard to understand, but the frustrating thing is that they often escape a pilot who, in spite of being only a matter of 300 or 400 feet above the ground and losing all power in a machine that may lose speed very rapidly, will attempt a 180+ degree turn back to the runway he has just left and unfortunately crash to his death without completing the manoeuvre. If complete failure of the engine occurs, the following sequence of events ensues: There is an immediate deceleration of the aircraft, resulting in the margin over the stall speed being eroded very quickly.

16 There is a delay while the pilot realizes what happened and starts to take corrective action. This delay is longer than might be imagined. The nose of the aircraft is lowered to a position below the horizon (let s say notionally to the approach attitude) and the pilot feels comfortable with this. A turn is attempted to the familiar aerodrome behind the pilot, rather than the alien territory ahead, and the aircraft never makes it. It either strikes the ground still turning, without making it around the 180+ degrees, or control is lost and the aircraft spins out of the turn and impacts vertically. Following an engine failure, the aircraft describes a curved flight path as the pilot pushes over into the approach attitude. During this curved manoeuvre, everything is changing, pitch attitude, airspeed, G loading. When the approach attitude is eventually attained, the pushover is terminated and aircraft is apparently stable at its new attitude. Energy management The total energy stored in an engineless aircraft is the sum of two component parts: Kinetic energy i.e. the aircraft s speed Gravitational potential energy i.e. the aircraft s height above the ground. These two sources of energy can be interchanged (up to a point). Indeed they must be interchanged when an engine failure occurs after take-off. Height must be traded for speed in other words the nose must be lowered if the total energy level of the aircraft is to be maintained. If the nose is not lowered sufficiently, and if sufficient time is not allowed for the speed to increase and stabilize, it may not be possible to control the aircraft to a safe landing. Let s take an example of a high-drag aircraft of relatively low mass, such as a Thruster or a Drifter. Both these aircraft have thick high-lift wings which give a good climb rate at about 50 knots. The trouble is that, should the engine fail at under about 150 feet AGL, taking into account the factors covered earlier, it is unlikely that the pilot will be able to

17 get enough speed in the available height to enable the aircraft to be flared for a normal landing. A heavy landing, possibly a very heavy landing, is almost inevitable. The theorists would tell us that 150 feet gives insufficient potential energy to allow a pilot to attain the required level of kinetic energy (speed) to level the aircraft off near the ground and achieve a smooth landing. From 150 feet, there just isn t enough room to get the required speed. The lure of the aerodrome behind you When an engine fails after take-off, there is a strong psychological urge to try to get back to a landing area that is not only familiar to you, but also of known quality. The reasoning seems to be Why put down in a paddock which might contain a variety of unpleasant surprises when I can return to my familiar airfield which I know I can land on because I have done it hundreds of times? Attempting to return to the airfield is therefore a very human and entirely understandable reaction to an engine failure after take-off. Unfortunately it is almost always the wrong decision at low-level and it simply has to be trained out of a pilot. This is what all those tedious practice engine-failures are all about instructors are keen to develop a conditioned response which will take over under the stress of an engine failure and overcome the return to the womb tendency lurking just beneath the surface of a pilot s thinking and which is quite likely to kill him/her if allowed to dominate. Bottom line Turn back or no turn back, energy management is the key to survival in low-level engine failures. If you are low and slow, you are playing with fire. Oh, and don't forget to plan ahead. Engine failures are not a matter of "if", but "when". Mike Valentine, Operations Manager

18 The information reproduced below was carried in Vector, 1998, Issue 3; a New Zealand Civil Aviation Authority flight safety publication:

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20 1.17 Organizational and management information The pilot was also the owner of the aircraft. Light Plane Maintenance Limited was the Approved Maintenance Organization Additional information None 1.19 New investigation techniques None required and none were used.

21 2 ANALYSIS During the climb in the upwind leg of runway 14, the pilot reported to ATC that he wanted to land immediately on runway 32. At this time, the succeeding aircraft on runway 14 was already lined-up and was advised to immediately vacate the runway in order to give way to the accident aircraft. Following an engine failure at low level, height must be traded for speed, in other words the nose must be lowered, if the total energy level of the aircraft is to be maintained. If the nose is not lowered sufficiently, and if sufficient time is not allowed for the speed to increase and stabilize, it may not be possible to control the aircraft to a safe landing. The maximum rate of climb for the Skystar 7 is 1200 feet per minute. It is noted that the aircraft took off at 0414 and crashed at 0416 hours. This is a flight time of about 2 minutes. If we take into consideration the reaction time for the pilot and the initiation of the turn back maneuver, the aircraft had been climbing for less than 1 minute. It is also possible that it was not climbing at its best rate of climb. The aircraft had, therefore, not gained enough altitude to execute a successful turn back to Runway 32. It crashed 200 meters short of the runway. Following the rule of thumb cited above, the pilot should have selected a landing area ahead of him and force landed in the Nairobi National Park.

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23 3 CONCLUSIONS 3.1 Findings The pilot requested ATC that he wanted to land immediately The pilot selected Runway The pilot did not say why he was turning back The aircraft had not gained enough altitude to be able to execute a successful turn back. 3.2 Probable cause The probable cause of this accident was the pilot s decision to turn back and land on Runway 32.

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25 4 SAFETY RECOMMENDATIONS Pilots to be sensitized on the need to adhere to emergency procedures as outlined in the Pilot Operating Handbook. CHIEF INSPECTOR OF AIR ACCIDENTS

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27 Crash site Flight path Crash site

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