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A109S Medevac Crash Brainerd Minnesota

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A109S Medevac Crash Brainerd Minnesota

Old 30th Jun 2019, 11:05
  #21 (permalink)  
 
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Originally Posted by ShyTorque View Post
gulliBell, I don't understand your reference to "leveling off" during an ILS..
Fly level to capture the GS, sure. Once the GS is captured there are only two choices. Down or Up. There is no leveling off.

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Old 30th Jun 2019, 11:15
  #22 (permalink)  
 
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And another question may be what seats were fitted. The answer to that question can turn an unfortunate hi-G injury accident where everyone walks away into a fatal.
The 109 is a legacy airframe and some of the original seat options are not crashworthy. The rear bench is no place to be but the pilots seat is usually stroking and modern.
It would not be the first time that an EMS 109/119 has simply killed by a lack of a stroking seat.
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Old 30th Jun 2019, 13:16
  #23 (permalink)  
 
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Once the GS is captured there are only two choices. Down or Up. There is no leveling off.
At what point does the ILS Procedure end?

We must assume you are using the criteria of the Pilot gaining adequate visual reference to allow for a decision to land as being part of the definition.

DH is the height above ground that the Pilot must declare his intention to land or go around....right?

In reality....it is far more common to make that decision well before DH if the existing weather conditions allow for an "early" decision.

I am thinking you are failing to understand my post where I described the Sperry system being able to fly the aircraft at a fixed height down the runway as being part of a legal IFR procedure....which it certainly is not.

The point was demonstrate most helicopter autopilot systems can provide better flight performance than is allowed by the Authorities.

In extreme cases....which sometimes we find ourselves in for any number of reasons outside our control...we might have to exceed those legal limitations to safely land the aircraft.

Knowing what your aircraft is capable of doing...and knowing how to use those capabilities might just save your Bacon when you need it.

As to all the jabber about aircraft attitude changes....again...knowing how to fly the machine is a good start on understanding what it is going to do when you move the controls.

If you set the aircraft up in a minimum safe airspeed configuration before intercepting the Glide Slope....(I used 60 Knots IAS)....upon intercepting the Glide Slope (I never had an autopilot that controlled the power) you reduce the Collective Setting to maintain the Glide Slope)...pitch attitude changes were minimal and only transient.....you certainly did not wait for the nose to dip upon intercepting the Glide Slope.

At the bottom....you had to increase Collective slightly to stop the descent and the autopilot took care of the Pitch Attitude changes needed to maintain that same IAS.

The key....is thinking outside the box...practicing the "new" procedure to see how it all works.

Nothing unsafe about it....and it adds another Tool in your box you might need to drag out and use some day.

When you fly in areas that can be invested by Fog over very large areas and see your planned but well distant Alternates go below minimums with scant notice....you start thinking about these kinds of things.

There are no helicopters in Orbit around the Earth....thus at some point you must land....no matter what the weather you find yourself dealing with.
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Old 30th Jun 2019, 13:34
  #24 (permalink)  
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Originally Posted by ShyTorque View Post
Unfortunately, the A109S autopilot isn't quite so sophisticated as that in the S-76.

The AP has no facility to carry out an ILS with the aircraft holding a set airspeed (the collective isn't coupled and there is no altitude pre-select facility). During the ILS the airspeed is controlled by the pilot using the collective and it can be counter-intuitive until you are used to it; it will easily go through Vne or VLE (max landing gear extended speed) as it couples to the G/S and noses down - it's a slippery beast and can get away from you. At lower IASs, with the AP fully coupled, the aircraft seems to "wallow" as if the AP is struggling - it's designed to fly fast.

The AP is capable of leveling the aircraft at the completion of the ILS but at that stage the airspeed still has to be controlled by the pilot using the collective. It's actually quite unnatural to significantly lower the lever - lowering the lever brings up the nose, rather than the possibly more usual expectation of it causing the nose to drop. If you are still in fog at that stage and not used to it, possibly more than a little disorientating.
I remember an autopilot equipped BO105 accident some years ago that was attributed that was attributed to confusion as to how the collective interacted with the autopilot. I'll see if I can find that report, I don't recall specifics other than fatal, night, HEMS, pilot only on a short hop to the airport while the medicals packaged the patient for transport.
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Old 30th Jun 2019, 15:22
  #25 (permalink)  

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Originally Posted by gulliBell Fly level to capture the GS, sure. Once the GS is captured there are only two choices. Down or Up. There is no leveling off.
No-one said or implied that one would level off during the approach on the GS per se.
But if visual after DA/DH you are no longer using the ILS, unless you have helicopters fitted with auto-land, which I don't think currently exist. The A109S certainly doesn't have that facility.
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Old 30th Jun 2019, 16:53
  #26 (permalink)  
 
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Originally Posted by SASless View Post
...
I am thinking you are failing to understand my post where I described the Sperry system being able to fly the aircraft at a fixed height down the runway as being part of a legal IFR procedure....which it certainly is not.
...
Originally Posted by ShyTorque View Post
No-one said or implied that one would level off during the approach on the GS per se.
But if visual after DA/DH you are no longer using the ILS, unless you have helicopters fitted with auto-land, which I don't think currently exist. The A109S certainly doesn't have that facility.
Absent a limitation, why decouple simply because the runway environment is in sight? Especially in low IFR conditions.
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Old 30th Jun 2019, 17:02
  #27 (permalink)  
 
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Originally Posted by rotorspeed View Post
Strange one here. Be key to know what runway they were using and approach they were on.
Under typical OpSpecs, I don’t think executing the GPS RWY 5 was legal given the weather, without an approach light system. However, it is usually allowed a straight-in reduction of visibility/RVR by one-half if flown at <90 knots. That would probably make ILS RWY 23 or 34 and LPV RWY 34 legal options. I didn’t find any NOTAM preventing those selections.
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Old 30th Jun 2019, 17:25
  #28 (permalink)  
 
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Absent a limitation, why decouple simply because the runway environment is in sight? Especially in low IFR conditions.
Who said anything about de-coupling the Auto-Pilot?

At some point one must do so....so where would you do that?

Some grist for the mill.....


https://www.faa.gov/air_traffic/publ...section_1.html

Last edited by SASless; 30th Jun 2019 at 17:43.
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Old 30th Jun 2019, 18:14
  #29 (permalink)  

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Originally Posted by JimEli View Post
Absent a limitation, why decouple simply because the runway environment is in sight? Especially in low IFR conditions.
Personal choice, but if you don't decouple, the AP will level the aircraft and fly it down the runway and the pilot will need to control the speed by lowering the collective....!!

As I already wrote:
The AP is capable of leveling the aircraft at the completion of the ILS but at that stage the airspeed still has to be controlled by the pilot using the collective. It's actually quite unnatural to significantly lower the lever - lowering the lever brings up the nose, rather than the possibly more usual expectation of it causing the nose to drop. If you are still in fog at that stage and not used to it, possibly more than a little disorientating.
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Old 30th Jun 2019, 18:24
  #30 (permalink)  
 
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Yes, perhaps one of the reasons for having a minimum of 200' DH for a Cat 1 ILS - the AP is capable of putting the pilot in a very uncomfortable situation.

Personally, I dislike 3 axis APs especially when used for approaches - it is too easy to forget that collective is controlling your IAS whether you are in IAS or VS mode and most counter-intuitive for many helicopter pilots.
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Old 30th Jun 2019, 18:43
  #31 (permalink)  
 
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As Attitude and Power equals airspeed or altitude/height.....and the Auto-Pilot is maintaining height (thinking of the bottom of the approach)....what is counter-intuitive about having to lower collective (reduce power) to slow down?

If you do not adjust power as the aircraft levels due to the auto-pilot attempting to maintain a height....the aircraft will pitch upwards and slow down.....fail to add some power and you might well get too slow, lose auto-pilot authority and see a downward trend on height.

If the basic laws of flight escape you....perhaps you might just be in the wrong profession.

A few minutes of practice now and then is a simple way to stay in touch with those basic relationships.
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Old 30th Jun 2019, 18:47
  #32 (permalink)  

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Again, to clarify, in the A109S you can't be in IAS mode when fully coupled to the ILS. The AP maintains the LOC and GS but the pilot has to control the IAS by use of the collective.

If ATC are vectoring you to fit in with faster jet traffic at a busy airport they will usually expect you to fly at "best speed". I previously mentioned that because as the aircraft automatically captures and descends on the G/S, it will do it by lowering the nose. Unless you lower the lever promptly the AP will happily take you beyond VLE, or even VNE if you aren't careful. This can require a large power reduction = a large downward movement of the collective. On these aircraft the yaw pedals need to be respositioned by the pilot, even if AP inputs requires pedal position changes. The YAW pedal trim is released via the button on the cyclic. The pilot therefore has to allow the AP to fly the ILS but must manage the collective and the yaw trim. For those used to helicopters such as the S-76, where the AP also manages the yaw trim without any pilot intervention, it feels quite strange.

When I transferred from almost ten years on S-76s it took me quite a while to get used to the differences - I'd developed rather "lazy" feet.

By the way, SAS - I've never heard of anyone ever attempting to begin to fly an ILS in a A109S at 60 kts! 55kts is the minimum IFR speed for the type. From about 3,000 hours on type, I can tell you first hand that about double that speed works best. For me, after forty years of successfully flying RW instrument approaches, I'm probably a bit too old to change careers.
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Old 30th Jun 2019, 21:32
  #33 (permalink)  
 
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Shy,

Flexibility of thought as well as feet is a useful attribute in flying helicopters.

A casual reading of my posts should] surface adequate notice that the 60 Knot Speed I discussed was in conjunction with a "non-standard but quite legal ILS approach technique" that falls well within the capability of most auto-pilot equipped helicopters.

I would submit that if you fly a helicopter like a jet airliner then you deprive yourself of the unique aspects of the helicopter.

Where this particular 109 came to grief is not a busy airport....especially at the time of night it happened.

I have done ILS approaches at West Palm Beach in brand spanking new S-76's at speeds in excess of Boeing 727's....with ATC asking if they would speed up as there was overtaking traffic behind them......ask John Dixson about such happenings for verification.

I have also done them at the minimum speed as well.

At Malpensa International....I have even backed back up the ILS Approach in a Chinook on one occasion (not IMC but in solid Gin Clear conditions) ....but that is a yarn for another time.

You choose the speed that fits the occasion...considering traffic, weather, and technique that affords you the best chance of landing safely without having to resort to a missed approach.

In craggy weather I would rather transition from DH at a stately slow speed than streak down the runway trying to get stopped.


Why would you want to hit minimums at 120 KTS if you could do so at 60 KTS?

If you are going to do a Missed Approach at DH.....do you use Vbroc or your 120 Knot approach speed?

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Old 30th Jun 2019, 21:47
  #34 (permalink)  
 
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As Attitude and Power equals airspeed or altitude/height.....and the Auto-Pilot is maintaining height (thinking of the bottom of the approach)....what is counter-intuitive about having to lower collective (reduce power) to slow down?

If you do not adjust power as the aircraft levels due to the auto-pilot attempting to maintain a height....the aircraft will pitch upwards and slow down.....fail to add some power and you might well get too slow, lose auto-pilot authority and see a downward trend on height.

If the basic laws of flight escape you....perhaps you might just be in the wrong profession.

A few minutes of practice now and then is a simple way to stay in touch with those basic relationships.
Sasless - while you are busy teaching us to suck eggs, just remember that A. you are not the only helicopter pilot in the world who can fly an ILS (or even go backwards up it - and old trick from Shawbury to confuse trainee ATCers) and B. that lowering the lever on a coupled ILS in a 3 axis AP will cause the IAS to reduce - I am not talking about the auto level portion well after DA/DH - which is how the Sumburgh aircraft ended up in VRS and the sea - using power to control IAS in this way is counter intuitive. Whilst I agree that practice helps, so does a 4-axis AP that flys height/RoD using collective and IAS using cyclic which is how most of us are taught to fly a manual ILS
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Old 30th Jun 2019, 22:40
  #35 (permalink)  
 
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Just throwing out a random thought with zero evidence, as are the rest of everyone as well.

I think he successfully accomplished the approach but failed to go visual, at night, with wx likely below appch mins, and this is a simple loss of control. Itís not unlikely he had minimal aircraft lighting turned on with the fog conditions, and may have not had a lit up appch lighting system or may not have keyed airport lights during his high workload, and simply failed to transition to visual flight.
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Old 30th Jun 2019, 22:55
  #36 (permalink)  
 
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The Airport director was quoted in the media as saying the weather at the time of the accident was foggy but above minima. For what that's worth.
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Old 1st Jul 2019, 03:17
  #37 (permalink)  
 
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Interesting graphic that depicts the visibility being reported at the time of the accident.

No idea how accurate it is but it is in the public media.

https://www.kare11.com/article/news/...8-9e114faa9d08
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Old 1st Jul 2019, 03:26
  #38 (permalink)  
 
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Missed the runway by quite a bit. They also had a total hull loss prang in 2016 which was blamed on pilot error. I wonder if their pilots attend simulator training?


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Old 1st Jul 2019, 08:47
  #39 (permalink)  

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SAS, Thanks, but you perhaps forget others here also have considerable experience of helicopter instrument approaches in all sorts of circumstances - there are even some of us with relevant type ratings and a lot of hours on the type...in my case as many as you previously said you flew on the Chinook. I had already worked out that one needs to fly with consideration of the prevailing conditions, but thanks for the reminder.

I have no reason to ask JD to corroborate your story about the speed at which you flew that ILS at WPB; I believe you, it's not unique (I have been in a situation in an A109S where, having been directed by ATC at a major airport to "make best speed" on the ILS to fit in with the busy airliner traffic I was shortly afterwards asked to slow down again because I was catching up the B767 established ahead of me).

Are you saying that you usually changed the IAS on a S-76 on a coupled ILS by manually lowering the lever, or did you use the "Beep" trim with IAS mode selected, as per normal teaching and allow the AP to reduce the power accordingly? I did the latter, as I was taught to do and expected to do for the nine year period I flew them (A, A++, B, C and C+).

Did you keep your feet on the side rests on the yaw pedals and away from the yaw micro-switches so the AP could make it's own yaw inputs? I certainly did.

Unfortunately, you don't have that luxury of doing either in the A109S - the aircraft has no IAS mode when coupled on the ILS and the AP requires the pilot to make all yaw pedal inputs himself and to re-trim them, the trim release button on the cyclic has to be used. In effect, the A109S cannot be flown "fully coupled" on an ILS, unlike more sophisticated aircraft.

When it comes to a speed reduction near the ground, the normal teaching (at least the teaching I am familiar with) is to initiate the manoeuvre by using the cyclic to raise the nose to a decelerative attitude then to maintain the required flight path by lowering the collective. In the A109S, if still coupled at the bottom of an ILS and the system has levelled the aircraft at 50 feet (as advertised), to reduce speed the pilot has to first lower the collective and trust that the AP will prevent a descent by raising the nose. If you try to move the cyclic first you will find yourself working against the trim - not something you should be doing near the ground in poor visibility. The more sophisticated types such as the S-76 (and. I believe, the A109SP) will slow down all by itself in the same circumstances because the collective is also coupled).

It's unlikely we will ever know what this unfortunate pilot did because there is no FDR on the type. I would be interested to find out what his previous experience was.
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Old 1st Jul 2019, 09:13
  #40 (permalink)  
 
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We might know. There is a survivor. Well, I think there is (there has been no mention of his condition since the accident). In which case he might be able to provide useful information to the investigation.

Given the reported weather, the final disposition of the aircraft, and what ShyTorque has described of the A109S autopilot system, this is strongly leaning towards pilot loss of control close to the ground at night in non-visual conditions.
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