C182 – NEARLY MADE IT?
This discussion is to promote safety and not to establish liability. CAA’s report contains padding and repetition, so in the interest of clarity, I have paraphrased extensively.
Aircraft registration: ZS-PHB
Date and time of accident: 27 August 2016 1025Z
Type of aircraft: Cessna C182Q
Type of operation: Private (Part 91)
PIC license type: Private Pilot
License valid: No
PIC age: 39
PIC total hours: 342
PIC hours on type 311
Last point of departure: Komati Gorge Lodge private strip
Next point of intended ldg: Komati Gorge Lodge private strip
Location of accident site: Komati Gorge Lodge private strip
Airfield Elevation 4730’
Runway dimensions 800m x 15m (2625’x50’)
Meteorological information: 050˚/08kts, 24˚C, Dew Pt: -5˚C,
POB: 1+2
People injured: 0
People killed: 3
History of Flight
On the day before the accident, the pilot, who owned the aircraft, and a passenger took off from Nelspruit at approximately 1430Z. The aircraft was refuelled to capacity in Nelspruit. They flew to a private lodge 24km north-east of Carolina. They landed at approximately 1515Z.
The next day, at approximately 1025Z, the pilot and two passengers boarded the aircraft to conduct a short scenic flight in the area and land back at the lodge.
A witness, a guest at the lodge,saw the aircraft just after takeoff. He estimated its height at that point to be 30 feet above ground. He confirmed that he could hear the sound of the engine running, however, it sounded as though the engine was straining. He felt it was having difficulty maintaining height. Thereafter, the aircraft turned right and he heard a loud bang and saw smoke coming from the aircraft.
According to the second witness, a security guard working for the lodge, he heard the aircraft engine making an unusual noise, followed by a bang. He also noticed smoke and telephoned the lodge reception to notify them of what he had heard. He also notified the neighbour (next door to the lodge) who also confirmed that he had heard a loud noise.
The aircraft was certified to use 100 LL grade aviation gasoline (AVGAS). It was fitted with standard tanks of which the total capacity is 61 gal / 230.91 litres.
The aircraft was refuelled to capacity at Nelspruit Airport. At approximately 1430Z, it departed Nelspruit Airport for the private lodge. The distance from Nelspruit Airport to the lodge is approximately 42 nautical miles with the estimated flight time of 45 minutes. The 45-minute flight would burn approximately 6 gal / 22.7 litres of fuel. Therefore, the total of 56 gal / 211.98 litres of usable fuel minus the 6 gal / 22.7 litres burned = 50 gal / 189.28 litres of usable fuel remaining on-board when landing at the lodge.
Note: There are no aircraft refuelling facilities available at the lodge airstrip. This is possibly the reason why the pilot decided to carry two extra jerry cans of fuel on-board the aircraft. Each of the two jerry cans carried 25 litres of fuel. No evidence was found of the aircraft being refuelled at the private lodge prior to the flight. This suggests that the aircraft took-off with a total quantity of 189.28 litres of usable fuel in the tanks and with two 25-litre jerry cans of fuel on-board.
Aircraft Loading
The weight at takeoff was calculated as 2938 lbs which means it was 12 lbs below the maximum allowable takeoff weight of 2950 lbs.
The Airstrip
The airstrip had been constructed approximately a month before the accident. The surface was uneven and was topped with soft soil.
A substantial pothole was found on the centreline, 550m from the threshold of runway 06.
Wreckage and Impact Information
The wreckage distribution path was almost at 90° from the take-off direction. The right wing tip impacted the ground first and separated from the wing; it was located 29m from the main wreckage.
As the right wing impacted the ground, the aircraft rolled to the right and became inverted.
The propeller impacted the ground 10m from the initial point of impact. The propeller assembly had separated from the fuselage on impact and came to rest 17m from the first point of impact and to the right of the wreckage distribution path. The propeller showed evidence of rotation on impact.
The six attachment bolts on the propeller assembly were ripped out and the threads on these bolts were smooth.
The fuel tanks in both wings ruptured and the wreckage was consumed by fire.
It was not possible to determine the flap settings.
The POH says
NORMAL TAKEOFF
- Wing Flaps — 0° – 20°.
- Carburettor Heat — COLD.
- Power — FULL THROTTLE and 2400 RPM.
- Elevator Control — LIFT NOSE WHEEL at 50 KIAS.
- Climb Speed — 70 KIAS (flaps 20°). 80 KIAS (flaps UP).
SHORT FIELD TAKEOFF
- Wing Flaps — 20°.
- Carburettor Heat — COLD.
- Brakes — APPLY.
- Power — FULL THROTTLE and 2400 RPM.
- Brakes — RELEASE.
- Elevator Control — MAINTAIN SLIGHTLY TAIL LOW ATTITUDE.
- Climb Speed — 57 KIAS (until all obstacles are cleared).
- Wing Flaps — RETRACT slowly after reaching 70 KIAS.
SOFT FIELD TAKEOFFS are performed with 20° of flaps are achieved by lifting the airplane off the ground as soon as practical in a slightly tail-low attitude. If no obstacles are ahead, the airplane should be levelled off immediately to accelerate to a safer climb speed.
Note: The procedures for a soft field take-off and a short field take-off are similar in that the flap settings are the same and the aircraft is lifted off the ground as soon as practical.
The mixture should be leaned for takeoff from elevations greater than 5000ft to ensure maximum power.
The runway was 2624 ft long and the graphs show the distance required is 2459ft, a difference of just 167ft. However it’s not known where the takeoff run started. It’s likely that the pilot rotated too early without sufficient speed to climb, causing the aircraft to stall shortly after lift-off.
The POH states that runway conditions are calculated on level, dry, paved runways. The soft earth would have substantially decreased the aircraft’s ability to accelerate.
Probable cause:
The investigation could not find a definitive cause of the accident; however, it is likely that the aircraft’s performance was diminished by density altitude and/or the take-off configuration was incorrect, which would have caused the aircraft to stall shortly after takeoff.
The likely cause of the accident is that the aircraft was poorly configured, taking into account the density altitude and the effect on performance of the aircraft, which led to a stall shortly after takeoff.
Jim’s comments:
I nearly skipped past this one because it looked boring – same old, same old. An then it sank in that this is the very reason it happened – and keeps on happening.
There is no one big red flag that would say to me ‘Woa! this flight looks bloody dangerous – I wouldn’t fly in the back of that aircraft’. Nope, but if I started scratching around a bit, I would find several things that were just a bit too marginal.
Things that we have all accepted from time to time and got away with.
Perhaps the most serious was the soft surface. But how are do you evaluate that in terms of takeoff distance? Sure there’s a general rule that says add 15% to the book figure. But that’s just a blind guess. It’s a very rough rule-of-thumb that is meant to apply to soggy ground, deep sand, long grass and so on. But, how soggy? how deep? and how long? There are no numerical answers.
Then there’s a figure for the gross weight. We simply don’t know the gross weight within a couple of hundred pounds. No one was sure whether there was any luggage on board – the fire was too destructive to leave accurate evidence.
And how about the two jerry-cans of fuel in the back. Really not a good idea in the cabin because of the weight, the fire hazard and the question of how well they were tied down.
And technically the pilot was unlicensed – his medical had expired three weeks earlier. Did his disrespect for the law point towards a generally casual attitude towards safety?
And did he lean out for the takeoff? We don’t know, but at a density altitude of over 7000 feet he certainly should have done – it makes a hell of a difference to the power. But nothing different would show on the manifold pressure or the revs.
And the pothole in the runway. Was the pilot aware of it? And if so, was he planning to simply steer round it?
None of these points is a deal-breaker. But they do cause one to suck in one’s breath and wrinkle the brow. And that’s what makes this accident so important.
It’s shouting at me that in fact every one of these little flags should be a deal breaker. We know that one or more combined to kill three people and throw many other lives off track.
In a way it relates to last month’s discussion on the eroding of safety margins. Our tendency to justify lower standard because they have not caused any trouble so far.
Take home stuff:
Beware when everything seems almost okay, it only takes one of them to slip over the line and bring down the whole pack cards.