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SAR S-92 Missing Ireland

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SAR S-92 Missing Ireland

Old 16th Apr 2017, 12:10
  #1061 (permalink)  
 
Join Date: Apr 2000
Location: EGDC
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I'm not obsessed at all. It is a VFR arrival departure procedure from helipad to helipad
no, it is a WP to WP arrival/departure procedure and XA290 clearly gives you the history of the procedure and why it came to be - it is entirely legacy as I suspected.

Sadly, not updated for the modern age other than changing the WP names and designed for non-nvd night letdowns where a big flashing light on a rock would be a good way of confirming your position.
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Old 16th Apr 2017, 12:12
  #1062 (permalink)  
 
Join Date: Feb 2013
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Blackrock Sling vs Mayo. 80feet vs 300?

Remote contributing factor?
Could the crew have confused the height of Slingo Blacrock Lighthouse ( 80feet) and Mayo by asosiation. Not likely, but you never know.
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Old 16th Apr 2017, 12:12
  #1063 (permalink)  
 
Join Date: Feb 2008
Location: Ireland/Australia
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Originally Posted by XA290 View Post
Coastal radar navigation from the last millennium

25 Years ago, GPS was in its infancy as far as helicopters were concerned. Indeed, DECCA was still the primary navigation tool employed by helicopters involved in Oil and Gas and SAR both in the U.K. and Ireland. DECCA had moved on from the MK 19 roller map to the RNav1 and later the RNav2 computers but they were point-to-point navigation systems. There were no moving maps in helicopters in the 1990s. There was also no electronic nav kit in the back of civilian SAR S61s.

Coastal Navigation and let-down procedures for SAR using a point-to-point RNav2 computer was fraught with danger. Particularly when using DECCA as it was prone to atmospheric interference on that dark and stormy night when you would be quite possibly using it in anger.

For this reason, your position had to be confirmed against a separate source and this was the radar. Putting a waypoint on a piece of rock or a headland confirmed your position. If the waypoint appeared under an appropriate shaped radar return that cross referenced with the paper map you were holding you were where the DECCA RNav thought you were and let-down could proceed safely.

Back in 1995 the SAR contract was operated by Irish Helicopters and they had a waypoint on Black Rock as an IP for a let-down to Black Sod. It was called something different then to the one CHC use now but it was on the rock for the reasons I give above.

It was to confirm your position in an S61 using a generally good but possibly unreliable DECCA nav system and a good distance out from Black Sod to allow height loss after over flying the rock.

It seems that a legacy from a past generation using past generation kit was left in use and the seeds of this tragedy were sown in the early 1990s.

I hope this may shed some light on how this came about from a historical perspective and why there was a waypoint on Black Rock and not mid channel.
Beat me to it XA290. I was jut about to mention the legacy of the original Rescue 115 S-61 operated by Irish Helicopters in the nineties.
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Old 16th Apr 2017, 12:14
  #1064 (permalink)  
 
Join Date: Apr 2014
Location: Co. Kildare
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Blackrock Island

Cobbled this together from the Report
Blackrock Island Montage (1).pdf
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Old 16th Apr 2017, 13:01
  #1065 (permalink)  
 
Join Date: Apr 2008
Location: GB
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Originally Posted by gulliBell View Post
I think what you are saying is they are one and the same.
Yes.

Just as said by ukv1145 : "To be slightly pedantic, ALL aural alerts on the S92 except 'AIRSPEED, AIRSPEED' come from the EGPWS box (note: not triggered by - the recordings reside within the EGPWS processor and can be triggered externally as well as internally) So if you lose the EGPWS you lose all system aural warnings."
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Old 16th Apr 2017, 13:16
  #1066 (permalink)  
 
Join Date: May 2002
Location: Wanaka, NZ
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Originally Posted by P3 Bellows View Post
..Was it a generic EGPWS manual or the S92A flight manual that you grabbed? .
Honeywell Mark XXII Helicopter EGPWS manual (equipment cited in 3.5.1 as being fitted to the S92)
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Old 16th Apr 2017, 13:45
  #1067 (permalink)  
 
Join Date: Sep 2005
Location: W. Scotland
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The Irish AAIU prelim report is well written. The section on EGPWS is revealing for what it doesn't say. Honeywell seem at pains to point out the database is supplied by someone else, but on their website claim it is proprietary to themselves. The AAIU obviously isn't happy and says it it still trying to fully understand this issue. More to come I think.
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Old 16th Apr 2017, 13:53
  #1068 (permalink)  
 
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Location: Wanaka, NZ
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Originally Posted by dervish View Post
..Honeywell seem at pains to point out the database is supplied by someone else, but on their website claim it is proprietary to themselves.
All I can find in the manual (2012 version) is this:

"The terrain database is the heart of the EGPWS. The database includes information regarding terrain, airports
and obstacles such as towers, buildings and antennas, that are 100 ft or taller. It is important to know that
wires are not a part of the database at this time.
The system compares aircraft position and motion against the terrain and obstacle database to provide its
cautions and warnings. EPWS also provides non-database related warnings. It does so using a term known
as geometric altitude, which is derived from radar altitude, a GPS altitude, barometric pressure and aircraft
motion calculations"
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Old 16th Apr 2017, 13:57
  #1069 (permalink)  
 
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I would offer a bait - STABILISED APPROACH to MDA/H & MAPT
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Old 16th Apr 2017, 13:59
  #1070 (permalink)  
 
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What does the Manual say about User supplied data for inclusion in Updates?
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Old 16th Apr 2017, 14:09
  #1071 (permalink)  
ZFD
 
Join Date: Apr 2017
Location: Ireland
Posts: 5
Database approval

This EASA info gives the two scenarios for data base approval.

"There are two types of Letters of Acceptance

Type 1 LOA
Letter of acceptance granted where a Navigation Database supplier complies with EUROCAE ED-76 / RTCA DO-200A documents with no identified compatibility with an aircraft system. A Type 1 LOA confirms that the processes for producing navigation data comply with these Conditions and the documented Data Quality Requirements. A Type 1 LOA may not release navigation databases directly to end users.

Type 2 LOA
Letter of acceptance granted where a Navigation Database supplier complies with EUROCAE ED-76 / RTCA DO-200A documents and provides data compatible with specified avionics system(s). A Type 2 LOA confirms that the processes for producing navigation data comply with these Conditions and the documented Data Quality Requirements for the avionics systems specified. The Data Quality Requirements must be provided by or agreed with the specified equipment design organisation in accordance with a formal arrangement. A Type 2 LOA may release navigation databases directly to end users. Such releases may also include data packing tools, where the use of such tools has been demonstrated to be ED-76/DO-200A compliant. A Type 2 LOA holder may interface directly with data originators (such as State AIP providers and operators), or may use data supplied by a Type 1 LOA in which case interfaces with data originators may not be necessary."

https://www.easa.europa.eu/navigation-database-suppliers-letters-acceptance
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Old 16th Apr 2017, 14:12
  #1072 (permalink)  
 
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Originally Posted by SASless View Post
What does the Manual say about User supplied data for inclusion in Updates?
Nothing.

But I do recall contacting the terrain and obstacle database provider (about 5 years ago), and asked how to get the data for the area I was operating in updated because it was woefully inadequate. As I recall, the process had to be directed via the local CAA, and it quickly became apparent to me that nothing was going to happen any time soon. So I didn't bother pursuing it.
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Old 16th Apr 2017, 14:20
  #1073 (permalink)  
 
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So....we know Blackrock was not correctly represented in the current database....and there is no effective procedure to correct known deficiencies?
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Old 16th Apr 2017, 14:25
  #1074 (permalink)  
 
Join Date: May 2002
Location: Wanaka, NZ
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Originally Posted by SASless View Post
So....we know Blackrock was not correctly represented in the current database....and there is no effective procedure to correct known deficiencies?
There is a procedure, but as I mentioned, I tried to get an update happening for the area I was operating in but didn't follow it through because, after the exchange of several emails, I sensed I'd get nowhere with it for a very long time. The terrain and obstacle database subscription update service was expensive, and the data of our area was either wrong, or missing. The effectiveness of the system predicated on incomplete data was thus compromised, with little prospect of getting it corrected, and I would never rely on it for operational use. We just decided to opt out of paying for the update service altogether. For terrain avoidance in coastal areas I could always rely on the aircraft weather radar, and it was free. We did however stick with navdata update services as a current navdata is required to despatch an IFR helicopter in IMC. There is no such requirement for the terrain/obstacle database to be current.

Last edited by gulliBell; 16th Apr 2017 at 15:11.
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Old 16th Apr 2017, 14:41
  #1075 (permalink)  
 
Join Date: Mar 2017
Location: Ireland
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Originally Posted by gulliBell View Post
I just grabbed the EGPWS manual from our technical library...it helps when trying to understand something like this to have the book to refer to. Here is what it says:

Mode 6 provides audio call-outs for descent below predefined altitudes and minimums.
The report seems to suggest that they were in Mode 4B:

Mode 4B
: When the landing gear is lowered, Mode 4B becomes active and the boundary decreases to 100ft when above 120 kts. As airspeed decreases below 120 kts the warning boundary decreases to 10 ft
at 80 kts. The landing gear was down at the time of the accident.
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Old 16th Apr 2017, 16:14
  #1076 (permalink)  
 
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So, one question is - even if Blackrock had been in the database, would the EGPWS have alerted with the gear down at a speed of less than 80kts?

The interim report seems to indicate the look forward boundary is only 10' at 80 kts and only 100' at 120 kts with the gear down. At 120 kts the aircraft is travelling at more than 180 ft/sec and even at 75 kts it is doing over 110 ft/sec.
Are these boundaries reasonable for a helicopter at low level?

Perhaps the SOP for putting the gear down so early needs to be revisited.
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Old 16th Apr 2017, 16:32
  #1077 (permalink)  
 
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Originally Posted by agirl View Post
..The landing gear was down at the time of the accident.
In mode 4B, if the landing gear was down at the time of the accident, below 120kts, the aural warning at time stamp 2.03.09.026 on the CVR should have been "TOO LOW TERRAIN". The aural warning actually recorded at that time was 'TOO LOW GEAR", which means the gear was up. If the gear was up then the system couldn't have been in mode 4B, it would be in mode 4A. The standard boundary for mode 4A is at 150' RA. That's my understanding of reading the manual.

The report says low altitude switch was engaged. This is what the manual says about that:

"A LOW ALT switch allows for helicopter operations that require low altitude flight. Use this function for
flight at low altitude in VFR conditions. Engaging this function:
ƒƒ Inhibits Mode 1
ƒƒ Significantly reduces Mode 2 warning boundaries
ƒƒ Significantly reduces Mode 4 warning boundaries
ƒƒ Enables Mode 6 “Altitude-Altitude” call-out
ƒƒ Reduces Terrain Advisory look ahead distance
Low Altitude operation is defined as operation below 500 ft AGL, in a high-density metropolitan environment
with high-rise buildings, below 1,250 ft AGL when the GPS is not operational or is providing poor accuracy,
or airport maneuvering where airspeeds exceed 50 Kts"

Last edited by gulliBell; 16th Apr 2017 at 16:49.
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Old 16th Apr 2017, 16:36
  #1078 (permalink)  
 
Join Date: Sep 1999
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Could someone kindly tell me what the MSA is in the area of the approach they used.
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Old 16th Apr 2017, 16:44
  #1079 (permalink)  
 
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Since the aircraft had suffered 10 seconds of substantial impacts and considerable damage at the time of that call, our minds should be open to the idea that automated calls in that period do not reflect the true status before impact.
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Old 16th Apr 2017, 16:47
  #1080 (permalink)  
 
Join Date: Apr 2017
Location: Ireland
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Originally Posted by gulliBell View Post
In mode 4B, if the landing gear was down at the time of the accident, below 120kts, the aural warning at time stamp 2.03.09.026 on the CVR should have been "TOO LOW TERRAIN". The aural warning actually recorded at that time was 'TOO LOW GEAR", which means the gear was up. If the gear was up then the system couldn't have been in mode 4B. That's my understanding of reading the manual.

The report says low altitude switch was engaged. This is what the manual says about that:

"A LOW ALT switch allows for helicopter operations that require low altitude flight. Use this function for
flight at low altitude in VFR conditions. Engaging this function:
Inhibits Mode 1
Significantly reduces Mode 2 warning boundaries
Significantly reduces Mode 4 warning boundaries
Enables Mode 6 Altitude-Altitude call-out
Reduces Terrain Advisory look ahead distance
Low Altitude operation is defined as operation below 500 ft AGL, in a high-density metropolitan environment
with high-rise buildings, below 1,250 ft AGL when the GPS is not operational or is providing poor accuracy,
or airport maneuvering where airspeeds exceed 50 Kts"
The gear was extended during the descent and 3 greens confirmed locked down. As per interim report. The "Two low gear warning" was likely due damage from impact.
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