Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

SAR S-92 Missing Ireland

Rotorheads A haven for helicopter professionals to discuss the things that affect them

SAR S-92 Missing Ireland

Old 17th Apr 2017, 18:54
  #1141 (permalink)  
 
Join Date: Dec 2006
Location: UK and MALTA
Age: 56
Posts: 1,200
Ex Marina, you could be right. It's a few years since I used the radar in anger but I was pretty sure that how I managed it. The Search functions in my experience are too complex, probably for the reasons you describe and I do remember a few times realising we had no return on a target that was definitely there and realising the copilot had selected a search mode. A quick switch to WX mode and sudenly the target is a nice big red blob.
DOUBLE BOGEY is online now  
Old 17th Apr 2017, 18:59
  #1142 (permalink)  
 
Join Date: Jan 2011
Location: on the cusp
Age: 47
Posts: 217
In my experience a TSO compliant radar will not allow the operator to change gain in weather mode.
dClbydalpha is offline  
Old 17th Apr 2017, 19:02
  #1143 (permalink)  
 
Join Date: Oct 2012
Location: uk
Posts: 28
sorry gents, but maybe everyone who uses the radar offshore/sar should do some reading, my goodness!!!!!

Primus 660 radar

The GAIN knob is a single–turn rotary control and push/pull switch that is used to control the receiver gain. Push in on the GAIN switch to enter the system into the preset calibrated gain mode. Calibrated gain is the normal mode and is used for weather avoidance. In calibrated gain, the rotary portion of the GAIN control does nothing. In calibrated gain, the color bar legend is labeled 1,2,3,4 in WX mode or 1,2,3 in GMAP mode.
Pull out on the GAIN switch to enter the system into the variable gain mode with VAR (variance) displayed in the color bar. Variable gain is useful for additional weather analysis and for ground mapping. In WX mode, variable gain can increase receiver sensitivity over the calibrated level to show very weak targets or it can be reduced below the calibrated level to eliminate weak returns.
WARNING
HAZARDOUS TARGETS CAN BE ELIMINATED FROM THE DIS- PLAY WITH LOW SETTINGS OF VARIABLE GAIN.



Maybe this crew were as familiar as some here with the equipment they were using then it's no wonder accidents happen..(I am not saying they were, but some of the answers here from professionals who use wx radar is shockingly scary)!!!
Brutal is offline  
Old 17th Apr 2017, 19:03
  #1144 (permalink)  
 
Join Date: May 2002
Location: "Deplorable but happy as a drunken Monkey!
Age: 71
Posts: 16,313
Round,


When level at 200' or thereabouts, tilt control should be set about level which will give about +/- 3 to 5 degrees of scan above and below the horizontal depending on the diameter of the aerial.
"Level" to what would be the Horizon and compensating for Aircraft Pitch Attitude variation of what would otherwise be Wings Level in Pitch due to the speed it is flying? Is that the "Level" to which you refer?
SASless is offline  
Old 17th Apr 2017, 19:16
  #1145 (permalink)  
 
Join Date: Dec 2006
Location: UK and MALTA
Age: 56
Posts: 1,200
Brutal, thank you for confirming my actions. However your adminoishments also apply to me because I learned the Radar procedure a long while back and really just kept applying it to each new box we were equipped with.

Like I said for me the simpler the better. Start with max gain WX mode point at the sea and trim the radar up until the picture is clearer and reduce the gain to remove sea clutter. Served me well but maybe I should have read the books a little more.
DOUBLE BOGEY is online now  
Old 17th Apr 2017, 19:20
  #1146 (permalink)  
 
Join Date: Apr 2008
Location: GB
Posts: 67
All references to 'search' modes (SR1 or 2) denote Puma pilots and are not relevant to the Honeywell Primus 701 used in the S92. No such modes there . (Ok, unless you think of 'ground mapping' modes as the same. Don't shoot! )
GKaplan is offline  
Old 17th Apr 2017, 19:32
  #1147 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
Age: 52
Posts: 156
Originally Posted by SASless View Post
Round,
"Level" to what would be the Horizon and compensating for Aircraft Pitch Attitude variation of what would otherwise be Wings Level in Pitch due to the speed it is flying? Is that the "Level" to which you refer?
The 701A is gyrostab:ed up to 30 degree of combined nose up/down/bank angle.
The tilt value is refering to the horizon( info from IRS i think).

Depending on antenna, a wild guess of size the radar lobe on the S92 is somewhere around 8 degrees... wich means it will see 4 degrees up and down with zero tilt. Thats the zone of 'good returns', it will see and plot up to total of 14 degrees but not with the "calibrated" gain.
Rules of thumb for radar is one degree at one mile(Nm) makes 100 foot. So at 200 foot with zero tilt it should have sen ground(the sea level) as close as 0,5 mile in front.
AAKEE is offline  
Old 17th Apr 2017, 19:37
  #1148 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
Age: 52
Posts: 156
Originally Posted by Brutal View Post
sorry gents, but maybe everyone who uses the radar offshore/sar should do some reading, my goodness!!!!!

Primus 660 radar

The GAIN knob is a single...
I think most offshore/SAR people knows how to tune a radar.

You could start by refering to manuals for a search and rescue/ weather radar.

In some purpose, they dont do exactly the same thing. For wx, yes but...
AAKEE is offline  
Old 17th Apr 2017, 19:48
  #1149 (permalink)  
 
Join Date: Jan 2011
Location: on the cusp
Age: 47
Posts: 217
Can any S92 operators tell me the size/colour of FMS WP symbols? Are they overlayed on top of the radar video?
dClbydalpha is offline  
Old 17th Apr 2017, 20:06
  #1150 (permalink)  
puntosaurus
Guest
 
Posts: n/a
What a generous series of posts DB. And your original observation is very insightful. How could there not be an SOP for something this crucial. Let's hope there was here, and let's hope it's published in the final report.

Looks like roundwego is doing some research into the consequences of the Primus using the GMAP2 setting with 10nm range, so let's hope something good comes of that. It's suggestive that these settings are specifically referred to in the report as increasing the amount of clutter on the screen, and it was a high seastate night.

Would still love to know from users of this sort of kit what a rocky outcrop looks like on radar vs a distant headland. All the radar energy from any point in the scan's azimuth will come back from a very narrow range which the screen ought to interpret as a rough coastline rather than as a blob. And there should be nothing at all behind the coastline as it's in radar shadow. I think someone else was talking about this earlier.

Very hard to see how you could miss a feature like that and yet spot a generic blob at 6nm. But as they weren't expecting a rock, maybe they just tuned out or rationalised the echo as something unthreatening.
 
Old 17th Apr 2017, 20:36
  #1151 (permalink)  
 
Join Date: Dec 2015
Location: UK
Posts: 19
Brutal,

That might be the case on the Primus 660 but not the Telephonics RDR 1500B/1600/1700A systems. IIRC the L2 and 225 were fitted with RDR 1600 as standard in the UK so in Wx mode the receiver gain is preset and cannot be changed by the pilot. That is why I suggested a memory check for DB as I know he flew those types.

Shockingly scary? Perhaps not - it depends on your kit!
Ex Machina is offline  
Old 17th Apr 2017, 20:59
  #1152 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
Age: 52
Posts: 156
Originally Posted by Ex Machina View Post
Brutal,

That might be the case on the Primus 660 but not the Telephonics RDR 1500B/1600/1700A systems. IIRC the L2 and 225 were fitted with RDR 1600 as standard in the UK so in Wx mode the receiver gain is preset and cannot be changed by the pilot.
In Primus 701A the gain can be adjusted also in Wx mode. It can also easily be reset to calculated( fixed gain) to get the appropriate WX readings with correct colors. When used in Wx Alert mode the gain is fixed and cannot be changed.
If the above apply to S92 due to implementation etc, I do not know.
AAKEE is offline  
Old 17th Apr 2017, 21:05
  #1153 (permalink)  
 
Join Date: Oct 2012
Location: uk
Posts: 28
Thank you ex-machina, I cannot remember ever using a wx radar where the gain could not be adjusted in wx mode....maybe I have been flying too long??

AAKEE
"I think most offshore/SAR people knows how to tune a radar".

Sorry to inform you that many times I have witnessed, especially during checks pilots not properly using the radar...ARA overhead, in the descent I noticed a return that would be on our inbound track, we levelled off, turned to face the inbound track and had already reduced speed, then proceeded with the descent, with the tilt only just giving us a return at six miles, but not the previous target...when the P1 was questioned he hadn't noticed the return outbound and hadn't bothered to re-adjust the tilt to look for potential returns closer, and not understood that the reduction in airspeed made the nose pitch up slightly more, and lose the first return...very very simple errors, but potentially lethal....again, my post was not on specific radar types, but pilots failing to use/utilise/understand radar and it's pitfalls.

DB, I remember being taught that way too, full gain to start, adjust tilt, etc...
Brutal is offline  
Old 17th Apr 2017, 21:56
  #1154 (permalink)  
 
Join Date: May 2002
Location: "Deplorable but happy as a drunken Monkey!
Age: 71
Posts: 16,313
What was the CHC In-Service training routine for ICG Pilots and Crew?

Many years ago as UK SAR was being shifted to the Civvie side from the Military....Crab and others raised concerns that then existing Training Hours and array of Training Tasks might decline.

Anyone able to share their knowledge about ICG training?
SASless is offline  
Old 17th Apr 2017, 22:00
  #1155 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
Age: 52
Posts: 156
10 mile scale

For the comments on the 10nm scale, I dont se a big problem using 10mile scale.
This scale still shows everyrhing, scaled down though.

For a let down to hover( transition down) we use a fixed scale, more zoomed in than 10 nm. But then you do this close to something, and need to see this more in detail. I think there also a good thing to use a standard setting making you refer to the picture at a 'known' scale.

For a descent to below clouds and the plan to continue flying I think the idea to see radar returns that give you SA in the radar picture, for example the shore line or islands is good, that may be the reason for that selection. Too zoomed in and you loose the SA and the easy relation to a map/moving map and so on.
(I would have worked with radar settings, and scale to make sure but thats not the point here).
AAKEE is offline  
Old 17th Apr 2017, 22:34
  #1156 (permalink)  
 
Join Date: Sep 2009
Location: UK
Posts: 128
The wx mode of the S92 radar IS gain adjustable.

Something the size of Blackrock could not be missed whether in WX or GMAP. Quite a large return would be bright red on the screen, whether on a 10mile scale or smaller. Even if the gain was badly set there is still a noticeable difference in return colour. At 200' the tilt would have to be greater than +5 to start shrinking the contact.

LZ
Hot_LZ is offline  
Old 17th Apr 2017, 23:02
  #1157 (permalink)  
 
Join Date: Apr 2017
Location: Edinburgh
Posts: 4
I've been lurking here for the past few weeks since the tragic accident and haven't posted. However I have a question that is troubling me and would be grateful for any clarification that can be provided by y'all. I have read the AAIU report, and have looked at a number of Coast Guard related information resources that are available on the web.

My reading suggests that the IRCG ought never to have been tasked to deal with the SAR/Medevac incident in the first place. According to the AAIU report, "The position of the FV at the time of the call was N 54 17.450’, W 014 06.944’, which was 141 nm and bearing 270 degrees from Eagle Island, Co. Mayo. "

The North Westerly boundary of the Irish SAR responsibility is contained in the IRCG SAR framework, previously linked to here and available at http://www.dttas.ie/sites/default/fi...-framework.pdf

The Irish SAR 'box' is contained within the area identified by the coordinates laid out in Appendix 1.1 of that framework. These coordinates are listed as:

55 20N 006 55W - 55 25N 007 20W
55 20N 008 15W - 54 45N 009 00W
54 34N 010 00W - 54 00N 015 00W
51 00N 015 00W - 51 00N 008 00W
52 20N 005 30W - 53 55N 005 30W
54 25N 008 10W - 55 22N 006 55W

A depiction of that area is contained at Image 1 attached to this post.

Anything outside the Irish box lies with the designated UK SAR area, to be dealt with by UK-based SAR rather than Irish SAR. and is depicted on Image 2, which is taken from Annex 1 of the Strategic Overview of UK's SAR Operations published in January of this year.

Finally, Image 3 depicts my placing of the published coordinates of the North Westerly extremity of the "Irish SAR box", coupled with the coordinates of the FV published by the AAIU.

My question is this: Have I totally made a hames of placing the published coordinates onto my Google Maps?

Or,

Did that FV makes its call within the UK realm of responsibility, rather than that of the IRCG? If so, when the FV contacted Malin on that night, why did Malin start the whole process of tasking Irish SAR resources when the FV did not lie within its area of responsibility. Why did Malin not hand off to the UK- based SAR services instead?
Attached Images
File Type: jpg
Image1.jpg (67.3 KB, 96 views)
File Type: jpg
Image2.jpg (56.2 KB, 77 views)
File Type: jpg
Image3.jpg (20.5 KB, 28 views)

Last edited by Pruneface; 18th Apr 2017 at 14:26.
Pruneface is offline  
Old 17th Apr 2017, 23:42
  #1158 (permalink)  
 
Join Date: Dec 2013
Location: Norfolk
Age: 63
Posts: 3
The radar transmitter is pumping out pulses of energy of up to 1,000 watts. The receiver is designed to respond to returning echo signals measured in micro watts, a millionth of a watt. Even if the transmit/receive protection circuits work in around a microsecond, you will see nothing within a 300 metre range. If they take three microseconds to switch over, you are blind to everything within a kilometre. We are talking millionths of a second here to switch from 1000 watts out to a few millionths of a watt coming back! The technology is well proven, but transmit/receive delays increase as equipment ages, so close in blind spots get bigger. A crew may actually perceive the radar equipment as working better as it ages because of an apparent reduction in close in sea clutter.

As stated earlier, very strong local reflections can overwhelm the receiver protection circuits and render the radar blind even at longer ranges. It is possible to tune the radar to reduce transmitter power, reduce or tune out sea clutter, reduce receiver sensitivity, and digitally enhance the display picture, but this takes time and a certain degree of skill to optimise the settings.

Judging from the cockpit transcripts, I am pretty certain that the radar did not display Black Rock in any recognisable form due to the weather conditions at the time, incorrect mode or adjustment of the radar receiver, slow changeover of the transmit/receive protection devices, or possibly overload of the receiver circuits due to very high return signal levels. None of these scenarios would necessarily be apparent or present any real problems to the crew over open water looking for a vessel, particularly at longer range settings.

If Black Rock wasn't showing on the radar display, then the scepticism voiced by the pilot and delay in changing course, in response to the warning from the FLIR operator, makes perfect sense.
G0ULI is offline  
Old 18th Apr 2017, 01:32
  #1159 (permalink)  
 
Join Date: Aug 2007
Location: ireland
Posts: 4
radar ground mapping

I'm trying to inform myself of wx radar and its ground mapping mode, how it works, what it might look like etc.

I found the following old video helpful and in particular the part at 33:55 time linked below:

https://youtu.be/O4UxlOBvTkI?t=1975

and the attached image seems to show the red crescent shape of a mountain and its shadow into the "ground stripe"
Attached Images
player104 is offline  
Old 18th Apr 2017, 01:56
  #1160 (permalink)  
 
Join Date: Nov 2009
Location: Inverness-shire, Ross-shire
Posts: 1,207
That works out Pruneface. Double-checked the AAIU report and the Irish SAR Framework and put the numbers in Google Earth and it works out about 11nm into the UK SRR.
jimf671 is offline  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.