Jim Davis
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.
Date and Time of Accident: 15 September 2013 1030Z
Aircraft Registration: ZS-DWJ
Type of Aircraft: Piper Cherokee 235
Name of Operator: A J Fourie
Type of Operation: Private
PIC License Type: Private Pilot
Age: 55
License Valid: Yes
PIC Total Flying: 465.5 Hours
Hours on Type: 450.6
Last point of departure: Mabalingwe (FAMA), Limpopo Province
Place of intended landing: Vryburg (FAVB), North West Province
Airfield elevation: 3850’
Density altitude: 6750’
Location of the accident: 150 m NW of extended C/L of 04
Met: 350°/10KT, viz: 10 km, 35°C, no clouds
Number of people on board: 1+3
Number of people injured: 1+1
Number of people killed: 0
History of Flight
The aircraft took off from Runway 04 on a VFR private flight with four occupants on board. The pilot indicated he used a longer takeoff distance than normal to get airborne. Immediately after takeoff he experienced turbulence and the stall warning sounded. He then selected 25° of flap (initially 0° flap setting) and turned slightly to the left to position the aircraft into wind. During the turn the stall warning sounded and the pilot experienced excessive turbulence. The aircraft could not maintain flight and collided with trees and thereafter with the ground.
The aircraft sustained substantial damage. Minor damage was also caused to surrounding grass, and the ground was contaminated by Avgas and oil.
Weight of the aircraft: 729 kg
Pilot: 96 kg
Passengers: 185 kg
Fuel: (63 Gal) 190 kg
Baggage: 15 kg
Total: 1215 kg
This is 100 kg below the maximum take-off mass of 1315 kg.
Runway Dimensions: 1000m x 5m
Runway Surface: Asphalt
The POH calls for 0° of flap for a normal takeoff. 25° of flap should be selected for obstacle clearance, however this should be done before takeoff.
Additional Information
Eye witness report:
According to an eyewitness who was standing at the end of the runway, the aircraft used approximately three quarters of the runway before it got airborne. The witness also reported the aircraft was drifting to the right of the runway after takeoff. He then saw the nose of the aircraft briefly lowered before it pitched up again and entered into a turn to the left and loosing height before it hit trees to the left of the runway.
Runway 04 was used for the takeoff. The slope on Runway 04 was calculated to be a +1% slope. (33’ over 1000m)
Aircraft performance was reduced by three critical factors:
- High density altitude.
- High take-off weight.
- The upslope runway that was used for the take-off.
The takeoff direction was in a 040 degree direction and towards a mountain on the extended centerline of Runway 04. Several pilots were interviewed who regularly use the runway at Mabalingwe and all of them agreed they never depart from Runway 04 due to the up-slope of the runway and the mountain at the end of the runway.
During an interview with the pilot after the accident, he admitted to not performing weight and balance calculation before the flight. The pilot also mentioned that he could hear the stall warning several times after rotation. He stated that he could not give any explanation for his decision to takeoff-on the up-slope runway. The pilot also admitted he did not get any surface data for the area before take-off and that he could feel the decreased performance of the aircraft during the takeoff ground roll.
It is possible that the mountain was not clearly visible to the pilot directly after takeoff due to the higher nose attitude. This might have caused him to pull the nose higher than he would normally to avoid the mountain which he knew was in front of him but was perhaps unable to see.
Jim’s comments
Strangely, this accident, and many others, have a lot to do with listening to the locals. It sounds like Meneer AJ Fourie either didn’t sidle up to the elders to discuss the takeoff, or scorned their unanimous opinion that the uphill strategy bordered on suicidal.
Bear with me because the point is crucial – and can be life-saving.
You need to be a bit of a psychologist to get the best info from the parishioners. Even though you may never have met your advisor, his station in life should give you an indication of whether he or she (damnit I am being bullied into conforming with this ridiculous pronoun nonsense)…. where was I? Ah yes, we have to decide whether your informant speaks with forked tongue.
A couple of examples may help.
A while ago I was going from Kimberley to Kakamas or Kenhardt, or one of those gawdhelpus little places in the desert of the Northern Cape. As a new commercial pilot, I played by the rule-book, which told me that I was required to obtain all available weather info for the proposed flight. The met man, Comrade Olsweski, showed me the synoptic chart which vaguely indicated the possibility of a front in the area. So I phoned the destination police station for an onsite evaluation of prevailing conditions. I was put through to Sergeant van der Westhuizen.
“Man you won’t believe the beautiful weather we are having here today.”
“Ah, thanks man, that’s great. No clouds?”
“What do you mean no clouds? It’s pissing down – we haven’t had rain like this for five years.”
Or if you phone the manager of one of those remote hotels on the Wild-Coast, he’ll tell you that the runway is in magnificent condition, and no – they never get fog there in the late afternoon. He wants your business, so you would be wise to consult a less biased citizen.
We actually looked at a very similar accident recently with a 180 Cherokee taking off uphill at Volksrus – again all the natives agreed they never took off that way because of the slope and the wires you need to clear after takeoff.
It’s interesting to note that both aircraft crashed to the left of the runway. I can’t emphasize enough how much right rudder you need at low speed and high power – it’s close to FULL rudder. If you don’t use enough rudder then you have to compensate by using right aileron. This means that you are sideslipping – no wonder the poor aircraft can’t climb.
The 235 is a very capable load carrier and I suspect they would have made it easily if the pilot had used enough right rudder, and not pulled it off the ground too early – that’s a sure way of destroying takeoff and initial climb performance.
It’s very tempting to raise the nose early when you have a short runway and obstacles to clear. Rather let the aircraft accelerate to rotate speed in a level attitude, and then as soon as you leave the ground, level the nose and accelerate to Vx (obstacle clearance speed) in ground effect.
Many aeroplanes will never get off the ground at all if you rotate too early and too steeply. It’s known as being on the back of the drag curve.
As a matter of interest ZS-DWJ was one of the early 235s that could carry more than their own weight. They had an empty weight of 1440 lbs and a gross of 3000 lbs. There are almost no production aircraft in the world that can do this – regardless of size or type.
The report criticizes the pilot for not using the second notch of flap until he is airborne. I don’t agree – you accelerate better flapless and you can bang on flap when you are ready to fly. And while we are on the subject – the POHs for the entire Cherokee range, call for zero flap on normal takeoffs. I have found that they all come off the ground more smoothly and willingly when you use one notch. Don’t you love those manual flaps?
The 1% slope mentioned means that you climb 1m in every 100m travelled horizontally. In this case the runway climbs 33’ in its entire length of 3300’. Not a lot, but it can certainly make the difference between flying and crashing when you are faced with heavy loads and high-density altitudes.
Finally, there is no mention in the report of the pilot leaning the mixture to allow for a density altitude of nearly 7000’. Those big Lycoming love to be leaned. Horsey people will understand this simile: leaning is like turning your steed for home – there’s a wonderful boost of extra energy.
The POH says he needed an extra 500’ of takeoff run to allow for the 35°C temperature which pushed the density altitude up from an elevation of 3850’ to a density altitude 6750’. That’s an increase of nearly 3000’. Even toughies like the 235 and the C182 battle under these conditions.
Take home stuff
- Listen to the locals – except if they are the constabulary at Kakamas, or the proprietor of an establishment that stands to profit from your visit.
- Hauling the stick back seldom improves the takeoff.
- If you can’t see obstacles over the nose – either sit on a cushion, lower the nose or turn a bit to keep them in sight.
- On takeoff the chances are you are not using enough right rudder.
- Use the POH technique for short field takeoff an obstacle clearance climb.
- Leaning makes a hell of a difference.
- Ignore density altitude at your peril.