year ago there was interesting crash of Socata Tobago in our country.
our Air Accidents Investigation released final report (not in english)
obviously a pilot error, trying to take off from these conditions,mostprobably without flaps…
If anyone interested about details, let me know in this thread, I can do some translation of incident report
What is your country?
This accident on ASN: http://aviation-safety.net/wikibase/wiki.php?id=155883
Full accident report in Czech language here: http://www.uzpln.cz/pdf/incident_EjfzaC8p.pdf
Apparently the pilot tried to take off from a soaky wet grass runway, after being stuck there for a couple of days due to rain…
I can’t understand much Czech anymore but it sounds like there was 600m total available, which is marginal even for perfect grass, if at max weight.
The pilot (aged 75) died a few weeks after the accident, without speaking (or being able to speak) about it.
The TB POH, like all others I have ever seen, has no data for grass, and anyway grass data is basically meaningless. I recall one ~1000m takeoff roll in the TB20; the “grass” was dry but about 15cm long and full of hidden rough stuff (a place called Heywood Farm – would never do that again). The TB20 normally gets off in about 300m on tarmac.
I think the Cessna POH’s say to add 15-20% for grass, so I’ve always used that as a guide for planes that have no published t/o charts for it.
15-20% probably isn’t enough.
See this:
http://www.caa.co.uk/docs/33/20130121SSL07.pdf
The TB series have powerful all moving tailplanes and it’s possible to get the nose too high and end up with a huge ground run on takeoff as the drag in that attitude is large.
some facts from report
pilot aged 75, total time 2012hrs last 90days with TB10 14hrs
weight 1099kg (MTOW 1150)
rains for last 2 days before flight were 21.8 milimeters (which looks like to be high number)
rwy was waterlogged,
day -3, pilot +1 landed on LKVR, clear weather after shower, RWY was wet
day -2, plane refueled but no flight due to weather (raining)
day -1, raining whole day
day D – pilot found weather is fine for planned flight back to germany and was preparing for flight, seen another plane taking off
AFIS guy + some observer went to pilot inform him runway is in really bad condition, wet and there is a risk plane will “go over head” and he should not flight
Pilot understood this but informed he will fly.
AFIS guy goes back to his place, plane was taxiing to the north part of rwy 29, didn’t contact AFIS at all and start to taking off.
Taking off was aborted after 300-400 meters, wheels stucks in mud.
AFIS guy and that observer goes to plane, trying to push it out, without success.
Tractor was used to pull plane out of rwy back to tarmac parking place.
Pilot removed wheel cups (full of grass and mud) and cleaned wheels and plane with pressurized water. Wheel cups were not mounted back.
Observer told to pilot he should not flight again but pilot didn’t communicate with him
Pilot moving his aircraft to northwest corner of RWY 11, again no communication on AFIS frequency at all.
Take off was across runway from left to right, AFIS guy seen plane was not able to gain speed, flaps were not used (he is not sure with this due to point of view but positions of levers etc after the crash looks like they were not used. Also stating AoA was too big, front wheel was barely lift of out of rwy untill he lost plane from sight due to horizon
Observer from hangar place is stating the same, adding if plane was flying wheels were something like 10cm above ground, he can’t see
Tracks in grass shows plane goes out of rwy to the right after 600meters, continuing takeoff try on grass. He run over some mud road at the end of the airport, and 200 meters from the hotel he hit later. Left wheel track is ending 90meters and right 65 meters from the hotel. 47-36 meters from the hotel plane was banked to side right so wing was hitting some higher grass or so. Probably right as plane hits hotel banked 45 right
Text on this picture, from bottom to top,
Starting point,
Leaving rwy to high grass
End of wheel trails and wing to ground contact
and again from bottom to top:
wing trace in high grass
roof hit
wing edge hitting fence pole
IMHO a guideline like 15-20% is reckless.
That might be the difference between tarmac and really perfect grass, which almost doesn’t exist in the UK.
For a standard IFR type tourer i.e. fairly small wheels, I would multiply the tarmac figure by 1.5 and that assumes a basically good grass surface.
The TB series have powerful all moving tailplanes and it’s possible to get the nose too high and end up with a huge ground run on takeoff as the drag in that attitude is large.
That would be bad technique however. A soft field takeoff gets the nosewheel off the ground, but you are supposed to hold it only just off the ground, not 3 feet off
The actual ground run is no shorter with a soft field takeoff and I would think for any aircraft type is actually longer than tarmac – but it is an essential tool if getting out of a boggy field, or a field which is so rough you worry about your teeth falling out by the time out get out of there.
I think some people think a soft field takeoff produces a shorter takeoff run. It doesn’t.
LKVR TODA is 870 meters
report doesn’t says there was anything limited/changed or whatever
There is around 140 meters of grass in rwy 11 direction
report says that POH says it needs 474 meters in ideal conditions (dry, flat, nongrass) and it needs add 39% in case of high grass or wet grass which is around 660 meters together.
POH also says it is needed to add more than 39% in case of wet mud etc…
I’ve been told soft field technique differs for aircraft. Stick back on a Cessna gives more lift than the elevator down pressure, but on a Robin DR400 Remorqueur that doesn’t hold. My only soft field experience is taildragger. I’ve seen a Pa28-161 on starting to taxi dig in the nosewheel, and plough as more power was added, with no speed increase..