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-   -   Canadian accident King Air-200 loses both AH's in IMC and crashes (https://www.pprune.org/pacific-general-aviation-questions/632010-canadian-accident-king-air-200-loses-both-ahs-imc-crashes.html)

Centaurus 29th Apr 2020 11:06

Canadian accident King Air-200 loses both AH's in IMC and crashes
 
https://www.tsb.gc.ca/eng/rapports-r.../a19w0015.html


This accident report on a King Air 200 is from Transport Safety Board Canada.

The copilots AH was u/s after engine start. Normally the MEL would preclude flight. The captain assumed the copilots AH could eventually come good with time and elected to continue with the flight. The first officer was unhappy about the captain's decision. After takeoff it was obvious the F/O's AH was inoperative and he again told the captain who reassured the F/O the AH would come good eventually. In fact the AH was unserviceable.

During en route cruise in IMC the captains AH also failed. The autopilot disconnected. The captain attempted to fly on partial panel in IMC.but soon became disorientated

The aircraft went into a steep spiral dive and broke clear of IMC at 2000 ft agl. The captain was unable to recover in time and the aircraft crashed at 400 knots.




rodney rude 29th Apr 2020 22:46

Aaah stupidity Centy - what do we do about it? Does the report mention a 3rd AH? ( I will read it later) We do this stuff in the sim - we practice flight with true limited panel, no AHs - in that case it becomes not about accurate or even decent flying, it becomes about survival, and it can be done very effectively. I remember in the RAAF being made to fly an NDB in the Macchi with no AHs. Wouldn't say it was pretty, but it worked. But its much harder to train out stupidity and arrogance.


BTW - does anyone else hate the latest Budget ad with all the horses??? I know it has nothing to do with aviation, but it just annoys me so much

machtuk 29th Apr 2020 22:57

Couldn't be a more clear case of pilot error than this one! The old Beech is a good stable platform, surprised they got it that cocked up!

ravan 30th Apr 2020 00:28

To lose effective control so quickly suggests a lack of currency with limited panel. There is also a salutary warning about normalising any deviance - "it always takes some time to come up". Unfortunately, I have been guilty of that with some GA aeroplanes that I have flown in my early days, but I was lucky to get away with it and learn not to accept the deviations.

And Yes, Rodney Rude, I couldn't agree with you more about that daft Budget Direct ad!! Makes me not want to go to them for insurance!

pithblot 30th Apr 2020 00:57

This reminds me of the Westwind 1124 that crashed into Botany Bay In 1985 - an accident that would never have happened if even an ounce of honesty, integrity or airmanship was applied on any of a number of levels.

https://www.baaa-acro.com/crash/cras...ydney-2-killed

https://www.atsb.gov.au/media/24699/198502557.pdf

Rodney Rotorslap 30th Apr 2020 02:44


Originally Posted by rodney rude (Post 10767722)
BTW - does anyone else hate the latest Budget ad with all the horses??? I know it has nothing to do with aviation, but it just annoys me so much

Rotorslap is with you there Rude. I don't like people yelling at me. All their ads are dreadful except the UFO one, "Can't believe I said probe". Made me laugh every time.

I mentioned UFO hence restoring the aviation connection.

oldpax 30th Apr 2020 03:38

I recall all those students who thought going onto the link trainer was beneath them(especially Cranwell students)and so they would be dozing along on an exercise and the AH would be switched off!!Time taken to notice this was duly written down and then the fun began!!Panic panic!!!

Mumbai Merlin 30th Apr 2020 05:21

Mr Rude,

No 3rd A/H unless the operator install one.
If they had EFIS I believe there would be a 3rd unit with standby battery. They had Analogue gear from the early days.

KRUSTY 34 30th Apr 2020 06:14

Poor bloody F/O.

Wouldn’t be the first time a clearer thinking subordinate followed his Captain to an early demise.

Centaurus 30th Apr 2020 15:57


I remember in the RAAF being made to fly an NDB in the Macchi with no AHs.
Even in the 1950's during an instrument rating renewal in a RAAF Dakota, a mandatory part of the test was a single pilot limited panel, single engine aural null NDB instrument approach. Looking back in time it certainly increased your rate of scan. But really a useless exercise invented by Central Flying School instructors with nothing better to do.

XYGT 3rd May 2020 03:20

G’day Centaurus,

Am only a humble non-flying GA pilot nowadays, but in a C402, single engine, limited panel, NDB circling and missed approach was mandatory if you wanted your instrument rating to continue. So at least the GA examiners thought it was worthwhile.

Then again, most of them were ex RAAF except for two that I can remember.

And if you believe in the “train hard, play easy” which I do/did, it was worthwhile (but then again, I never had to do it for real so I cannot say if it was effective).

Never had to chase the ‘aural null’ stuff but on one occasion I started one of those DME homing debacles.

sheppey 3rd May 2020 04:42


Never had to chase the ‘aural null’ stuff but on one occasion I started one of those DME homing debacles.
I often wondered about the practicality of these requirements. While I am sure very few pilots ever had to do a an IMC DME Homing or an IMC aural null let down for real, these instrument let downs were well explained in the manuals issued to flight crew at the time. You could bitch all you like about the remote chances of ever having to fly these in your career. But it gave you confidence that if one of these events ever happened you had a fighting chance of survival.

It should be remembered that in those days hand flying on instruments was accepted as normal. Auto pilots were not that reliable and gyroscopic instruments could easily topple beyond certain angles of bank - usually over 55 degrees. Keep in mind during wartime a dog fight would always cause an AH and DG to topple often in IMC. The pilot didn't have the luxury of holding straight and level unaccelerated flight while he caged then uncaged his AH and DG all the while with a Messerschmitt up his arse.

Skill at limited panel flying today is vital as a fall back in case an AH fails in cloud. Most flying schools have quite good desk top flight simulators at moderate cost for students and pilots to practice with. Unfortunately many pilots cannot be bothered - mainly because loss of face (not only an Asian characteristic I might add) when they finish up in an unusual attitude while trying to fly straight and level on primary panel.

Pinky the pilot 3rd May 2020 05:16

A slight thread drift;
Carried out at least three DME homing procedures whilst in PNG years ago. Coming back to Moresby from the "Jungles" and became stuck over a solid overcast which went many miles out to sea.

Homed to O/H the beacon then continued on heading until 6 DME past the aid. (well out to sea)
Commenced descent and became visual at 800' over the water. Then tracked back to the coast and got back in from the East.

Nothing dramatic. And I still thank Gerry L at the (now defunct, sadly) TKFS for teaching me that little trick!:ok:

Global Aviator 3rd May 2020 05:20

Yep to keep the basic skills is critical.

I’m certainly no test pilot, have flown a lot of GA, a few jets.

Enjoy going back to the 6 pack to get real again.

One of the hardest things I’ve done was the pc based sim, getting some limited panel thrown at me, that is a very fast challenge back to basics. Under the hood in the aircraft is great but unless your in the cloud it’s not the same.

It doesn’t matter how flash the pretty screens are in front of you, if you can’t use what information is available at times then............

Flying Ted 3rd May 2020 06:47

Hi Guys,
Can someone tell me what a "IMC aural null let down" actually is? Cheers FT

XYGT 3rd May 2020 07:56

First off – this aural null stuff was way before my time, and my time was when fixed NDB cards were standard. Never trained on it nor used it; this is just what I recall reading.



An NDB aerial on an aircraft was a circular loop in the vertical plane. You will recall seeing an open circular antenna on top of old aeroplanes or ones which have been covered by an aerodynamic housing.



If an NDB was broadcasting, an aircraft in range would be able to receive the signal. Say it is heading 060 and it can hear the NDB. To find its bearing to the NDB, the pilot would alter heading until no signal was detectable (the aural null) and then it would be at right angles to the NDB.



I think the null was received instead of using the strongest level because that 100% signal was too difficult to resolve.



But the null didn’t tell you whether the NDB was on the left or right of the aircraft. So, the pilot needed to do some manoeuvring to resolve the ambiguity. When he did, he or she could then track to the station



In general, I am pretty sure that is correct but I do not mind being corrected.



It was a bit like the start of the DME homing procedure in that you took up a heading, watched the miles and groundspeed (or mentally calculated it), tried another heading etcetera.

Capt Fathom 3rd May 2020 10:48

Aural null? I thought that was part of a VAR approach.

340drvr 3rd May 2020 12:20


Originally Posted by Capt Fathom (Post 10771200)
Aural null? I thought that was part of a VAR approach.

That's what I was thinking, too. Never heard of aural null in connection with NDB.

Capn Bloggs 3rd May 2020 13:13


Can someone tell me what a "IMC aural null let down" actually is? Cheers FT
From "I Flew For MMA":

"In the unlikely event of a failure of the sensing unit in the Radio Compass which drove the pointer needle, we were required to practice the Aural Null method of finding the station, called "Resolving the Ambiguity". This meant, from an unknown position, flying the aeroplane in a series of turns, manually rotating the loop aerial and listening to the rise and fall of a tone (the null being the point of lowest volume) in the headphones. This would tell on which side of the Station you were and whether going towards or away from it. Having resolved the ambiguity, you flew towards the beacon, following the aural beam in - the volume slowly rising as you approached - listening for the sudden null which signified the "Cone of Silence" and announced passage of the Station, after which you could then make an instrument let down through cloud to the assigned Minimum, become visual and land, or if still in cloud, climb away and go somewhere else. Quite old fashioned even then - and long gone now - and done completely by earphone noise, it was a quite fascinating, last ditch way to get yourself out of trouble in bad weather or at night."

Also:
https://www.casa.gov.au/sites/defaul...on-finding.pdf

:ok:

sheppey 3rd May 2020 13:57

VAR approach, Note the crossing of the station using the aural morse code from A's to N's. This was not an Aural Null approach which was an NDB system.
Mangalore VAR Approach Plate - 1967


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