A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Ventus 3F - Fatal



 
 
Thread Tools Display Modes
  #31  
Old Yesterday, 02:15 AM posted to rec.aviation.soaring
WB
external usenet poster
 
Posts: 164
Default Ventus 3F - Fatal

On Friday, July 20, 2018 at 6:30:07 PM UTC-5, Jock Proudfoot wrote:
National Transportation Safety Board
Aviation Accident Preliminary Report

The glider was equipped with a FLARM electronic flight collision
alerting device, which records flight track, altitude, and airspeed.
About 11 seconds prior to impact with the ground, the glider entered a
left hand descending spiral at an airspeed of 48 knots, which continued
to ground impact.

https://app.ntsb.gov/pdfgenerator/Re...atorFile.ashx?
EventID=20180710X25659&AKey=1&RType=HTML&IType=FA
.


Doesn't really sound like a stall/spin from low altitude. Sounds more like the behavior of a glider trimmed for an off-field landing with no one at the controls.
Ads
  #32  
Old Yesterday, 04:18 AM posted to rec.aviation.soaring
Steve Koerner
external usenet poster
 
Posts: 363
Default Ventus 3F - Fatal

On Friday, July 20, 2018 at 6:15:40 PM UTC-7, WB wrote:
On Friday, July 20, 2018 at 6:30:07 PM UTC-5, Jock Proudfoot wrote:
National Transportation Safety Board
Aviation Accident Preliminary Report

The glider was equipped with a FLARM electronic flight collision
alerting device, which records flight track, altitude, and airspeed.
About 11 seconds prior to impact with the ground, the glider entered a
left hand descending spiral at an airspeed of 48 knots, which continued
to ground impact.

https://app.ntsb.gov/pdfgenerator/Re...atorFile.ashx?
EventID=20180710X25659&AKey=1&RType=HTML&IType=FA
.


Doesn't really sound like a stall/spin from low altitude. Sounds more like the behavior of a glider trimmed for an off-field landing with no one at the controls.


WB: In what way does it not sound like stall/spin? Secondly, what do you mean about trimmed for an off-field landing? I've never heard about trimming differently for an on-field landing vs an off-field landing?

Separate remark: Flarm does not record airspeed as stated in the report. It could be that airspeed was inferred from the spiral descent dynamics; but that seems more complicated than suggested by the brevity of this preliminary report.
  #33  
Old Yesterday, 05:19 AM posted to rec.aviation.soaring
George Haeh
external usenet poster
 
Posts: 15
Default Ventus 3F - Fatal

Flarm obtains aircraft data from GPS and an internal static pressure sensor. Speed would be calculated from GPS position change and possibly altitude change yielding either 2D or 3D groundspeed, not airspeed.

Possibly wind aloft could be estimated from changes in groundspeed on different tracks and used to produce an airspeed, but any gusts would make a hash of such an estimate.
  #34  
Old Yesterday, 07:57 AM posted to rec.aviation.soaring
Mike the Strike
external usenet poster
 
Posts: 891
Default Ventus 3F - Fatal

On Saturday, July 21, 2018 at 5:19:42 AM UTC+1, George Haeh wrote:
Flarm obtains aircraft data from GPS and an internal static pressure sensor. Speed would be calculated from GPS position change and possibly altitude change yielding either 2D or 3D groundspeed, not airspeed.

Possibly wind aloft could be estimated from changes in groundspeed on different tracks and used to produce an airspeed, but any gusts would make a hash of such an estimate.


If you download the igc file from the Flarm into a program such as SeeYou, you will get a decent estimate of both ground speed and airspeed, presumably the latter calculated from the GPS ground speed, allowing for density altitude. I am assuming that the investigator was able to do this.

I examined Renny's previous two logged flights in the V3 at Moriarty and he maintained air speeds in excess of 60 knots on the descent to landing.

Given the good handling characteristics of the V3, I find it hard to believe that an experienced pilot like Renny misjudged his approach and entered a stall/spin and that some degree of pilot incapacitation seems more likely.

However, rather than speculate with incomplete information, perhaps we should wait for the final report.

Mike
  #35  
Old Yesterday, 10:15 AM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 223
Default Ventus 3F - Fatal

I would have interpreted the mention of 48 knots as being a descent rate shown on the data recorder file (= around 880ft/11seconds).
  #36  
Old Yesterday, 03:34 PM posted to rec.aviation.soaring
jfitch
external usenet poster
 
Posts: 896
Default Ventus 3F - Fatal

On Saturday, July 21, 2018 at 2:15:40 AM UTC-7, wrote:
I would have interpreted the mention of 48 knots as being a descent rate shown on the data recorder file (= around 880ft/11seconds).


The report clearly says airspeed not descent rate. Default Flarm setting is 4 second fixes so 11 seconds represents at most 3 fixes. 11 seconds from normal flight to impact indicates a very low altitude no matter how you interpret it.
  #37  
Old Yesterday, 03:56 PM posted to rec.aviation.soaring
Mike the Strike
external usenet poster
 
Posts: 891
Default Ventus 3F - Fatal

On Saturday, July 21, 2018 at 3:34:58 PM UTC+1, jfitch wrote:
On Saturday, July 21, 2018 at 2:15:40 AM UTC-7, wrote:
I would have interpreted the mention of 48 knots as being a descent rate shown on the data recorder file (= around 880ft/11seconds).


The report clearly says airspeed not descent rate. Default Flarm setting is 4 second fixes so 11 seconds represents at most 3 fixes. 11 seconds from normal flight to impact indicates a very low altitude no matter how you interpret it.


The previous two igc files of Renny's I looked at have the default 4 second recording interval. In these, it appears that he arrived back at Moriarty high and perhaps spoilered down, entering the pattern at around 1,000 to 1,500 feet AGL. In both of these landings, he maintained plenty of height and speed through his base and final turns, slowing down only on final just before touchdown. Of course, we have no idea what happened on his last flight, but his previous flights in the V3 show no signs of sloppiness that might result in loss of control.

Mike
  #38  
Old Yesterday, 04:02 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 9
Default Ventus 3F - Fatal

On Saturday, July 21, 2018 at 4:34:58 PM UTC+2, jfitch wrote:
On Saturday, July 21, 2018 at 2:15:40 AM UTC-7, wrote:
I would have interpreted the mention of 48 knots as being a descent rate shown on the data recorder file (= around 880ft/11seconds).


The report clearly says airspeed not descent rate. Default Flarm setting is 4 second fixes so 11 seconds represents at most 3 fixes. 11 seconds from normal flight to impact indicates a very low altitude no matter how you interpret it.


FLARM does -not- report or calculate airspeed. The device only calculates positions from GPS fixes and has a pressure sensor to enhance that information, but any airspeed or groundspeed calculations are only speculative approximations from the GPS data in the logs. From the GPS fixes of itself and those transmitted from nearby aircraft it then calculates threat levels and warns you appropriately if necessary.
  #39  
Old Yesterday, 05:41 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 393
Default Ventus 3F - Fatal

On Saturday, July 21, 2018 at 10:02:16 AM UTC-5, wrote:
On Saturday, July 21, 2018 at 4:34:58 PM UTC+2, jfitch wrote:
On Saturday, July 21, 2018 at 2:15:40 AM UTC-7, wrote:
I would have interpreted the mention of 48 knots as being a descent rate shown on the data recorder file (= around 880ft/11seconds).


The report clearly says airspeed not descent rate. Default Flarm setting is 4 second fixes so 11 seconds represents at most 3 fixes. 11 seconds from normal flight to impact indicates a very low altitude no matter how you interpret it.


FLARM does -not- report or calculate airspeed. The device only calculates positions from GPS fixes and has a pressure sensor to enhance that information, but any airspeed or groundspeed calculations are only speculative approximations from the GPS data in the logs. From the GPS fixes of itself and those transmitted from nearby aircraft it then calculates threat levels and warns you appropriately if necessary.


Another good reason to go to a 1 sec recording interval. Memory is cheap, why do people not use the best resolution our flight recorders offer?
  #40  
Old Yesterday, 06:12 PM posted to rec.aviation.soaring
George Haeh
external usenet poster
 
Posts: 15
Default Ventus 3F - Fatal

In my glider the Oudie receives and records TAS and Groundspeed supplied by the Air Glide S in one second intervals.

The instrumentation may offer more complete data.

If you happen to have advanced varios, you might want to leave some notes on what data can be extracted if your family and fellow pilots are looking for answers.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Fatal this afternoon Gene Seibel Piloting 6 March 7th 07 09:22 PM
1 Fatal ...r.a.h or r.a.p? Montblack Piloting 81 February 12th 06 08:54 AM
1 Fatal ...r.a.h or r.a.p? Montblack Home Built 99 February 12th 06 08:54 AM
1 Fatal ...r.a.h or r.a.p? Montblack Piloting 38 February 9th 06 02:00 PM
Fatal at Omarama Philip Plane Soaring 0 January 12th 05 07:52 PM


All times are GMT +1. The time now is 12:27 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 AviationBanter.
The comments are property of their posters.