Aer Lingus Viscount accident--off Strumble

[383656]

Viscount Crash

There were two books published relating to the crash and oddly enough both had the same title "Tragedy at Tuskar Rock" . The first was written by Dermot Walsh and published in 1983 the second was written my Mike Reynolds and published in 2004. The first book is based mainly on the 1970 Investigation carried out by the AAIU and the 2nd is supportive of and based on the 2002 International Team Study. Having read both books and the various investigations/reviews and studies I would suggest that some of the conclusions reached in the Study and therefor in the 2nd book should be taken with a grain of salt.

[narnia]

Ei-aom Viscount Training Dives

I was flying Aer Lingus Viscount EI-AOM on a training detail about a week before it crashed at Tuskar Rock. We were on a conversion course after basic training and we conducted high speed dives at the ground from 13000' before pulling out sharply with positive G. Additonally we used to do level approaches at Rwy 23 Dublin at 1000' and when the runway disappeared under the nose, the training Captain would close all four engines, and a courageous steep nose-down dive at the runway threshold was necessary to avoid going off the far end, followed by a positive G rotate and landing. I regarded these manoeuvres as highly stressful to the empennage and reported the matter to the last inquiry. I still think it was probably a metal fatigue structural failure of the tailplane or other elements of the empennage that caused the crash.

[383656]

Viscount Crash Tuskar 24th March 1968

Hi,
Just read your Dad's Night Order Book extract...brings back memories. I was a junior officer on the "Irish Frigate" mentioned on the left hand page...... in fact our ship was a Flower Class Corvette "L.E. Macha". Spent all summer off Tuskar Rock !!!
Best regards.

[383656]

Viscount Crash

It is hard to understand why neither crew or passengers had donned lifejackets even though EI-AOM was flying in a disabled condition for 30 minutes or so before crashing....that is, if we are to accept the findings of the 2002 International Team Study.

[RETDPI]

Sorry to blunder into this thread late and also far removed from any detailed knowledge of the case in question.
Possibly part of the "military aircraft mid-air" speculation came from, IIRC, the recovery of a nosewheel leg and some bits from what some in the the popular press at the time deemed to be an "RAF Fighter" , during the investigation.
Again ,IIRC, these bits turned out actually to have been from a Meteor which went in many years previously.

[llanfairpg]

Additonally we used to do level approaches at Rwy 23 Dublin at 1000' and when the runway disappeared under the nose, the training Captain would close all four engines, and a courageous steep nose-down dive at the runway threshold was necessary to avoid going off the far end, followed by a positive G rotate and landing.

Cant quite see that any useful purpose is served by this type of training or am I missing something, it would certainly bring some interesting pax comments!

[narnia]

Diving at runway from 1000'

Why do spectacular dives at the ground in a Viscount from just 1000'? I often wondered that myself as a trainee, but I was only 19 at the time and on initial four-engine conversion. I expect it would come in useful if you'd forgotten to descend below 1000' during final approach and, coincidentally, all four engines failed as you passed over the approach lights! I suppose it was to trigger the immediate response necessary for recovery from engine loss at low altitude so as avoid a stall and to effect an emergency landing.

My principal concern about doing unusual dive manoeuvres from 13000' on Oscar Mike a week before the Tuskar Rock crash was the effect on the tail structure of VMO dives with, first, sudden negative G in forcefully attaining at least 45 degree nose down as rapidly as possible to reach VMO (or whatever it was called in 1968), and then the less stressful level out at lower altitude (around 4000' if I recall correctly). I never heard whether the subject of my letter to the Inquiry was considered a possible factor in the accident, especially since the loss of tail elements was always part of the speculation.

[Panop]

RTE Radio have just done a Special on the crash.

See http://www.rte.ie/radio1/investigate/tuskar.html#

The programme can be heard at http://www.rte.ie/radio1/investigate...8/tuskar1.smil - it takes almost half an hour so give yourself enough time to listen carefully.

[DH106]

EI-AOM

I regarded these manoeuvres as highly stressful to the empennage and reported the matter to the last inquiry. I still think it was probably a metal fatigue structural failure of the tailplane or other elements of the empennage that caused the crash.
Capt Fergus Ryan, retd

Narnia - I completely agree that some sort of empennage failure is the most likely cause, but to someone with some aerodynamics knowledge the reported specifics of this accident are a real mystery....

Basically, in classic aircraft such as the Viscount, pitch stability is achieved by having the tailplane produce a downforce i.e. a nose up pitching moment which in stable level flight is balanced by the C.G. being forward of the centre of lift. So any empennage failure (say loss of elevator and/or tailplane) would upset this balance and cause the aircraft pitch sharply nose down. Several accidents have highlighted this:

1) Vanguard G-APEC 1971, near Aarsele, Belgium: Rear pressure bulkhead failed due to corrosion & caused tailplane failure - dived near vertically into the ground.
2) Boeing 707 G-BEBP 1977, Lusaka: Fatigue failure of right tailplane on approach - dived into ground.
3) Viscount SE-FOZ 1977, on approach to Stockholm: severe icing on the leading edge of the tailplane caused the tailplane to stall and near vertical dive into a parking lot.

So - I can't see it being a simple empennage failure or we'd almost certainly just have seen a near vertical dive into the sea off the south Irish coast. I doubt such a failure would be controllable/recoverable even with the height they had at the point of initial upset.
At least one witness reported the nature of the initial upset to be that of a spin/spiral dive. The Viscount then appeared, according to various witnesses, to fly erraticaly at fairly low level - at least once flying low enough to "flatten the grass" according to one witness. Another witness reported seing the faces of the passengers looking out through the windows - so again that must be pretty low level. The obvious speculation here is that the pilots were fighting some sort of controllability issue, but the fact that the aircraft spent some time at very low level but amazingly didn't hit the ground at these points suggests suggests that the aircraft was under some sort of pitch control (perhaps marginal?).

Analysis of the recovered aircraft wreckage suggests a fairly low forward speed (less than 130 knots according to analysis of the engines & prop pitches) but a high vertical descent speed - with possibly one wing lower on impact with the nose being somewhere between level pitch and 45deg nose down. The only condition I can visualize that fits all this is a spin - which makes an interesting comparison to the witness statement regarding the initial upset.

So - to sum up: what failure would give an aircraft marginal control for an extended period and perhaps a tendancy to spin?

[383656]

Viscount Crash

The following is a reply received from Colin Torkington in 2006 who was one of the three who compiled the 2002 Study.
"You asked whether an aircraft could enter a spin or spiral dive as a result of a near miss and could subsequent loading cause structural fatigue failure. I will do my best to answer.
Any aircraft making a determined pull up or even a rolling manoeuvre to avoid a collision could probably stall, drop a wing and spin or spiral dive. This was considered. The Viscount like most large aircraft, is definitely a non-spin aircraft. There was one case of a Viscount recovering from a spin but with extreme difficulty by an experienced test pilot.
It is indeed quite possible to break an aircraft in an attempted recovery from loss of control following an upset. This often includes a spiral dive and there have been many such cases.
In Australia, we lost three Viscounts with in-flight structural failure ( I was structures Group- Leader in two of the investigations ) The first one involving VH-TVC at Sydney in 1961 is relevant to your question, the others being fire and metal fatigue.
TVC suffered a catastrophic structural failure in attempting to recover from an upset and loss of control in a storm. Most such cases result in wing failure which was not the case with AOM.
If I remember correctly there have also been cases of engine mount and empennage failure.
There is a definite 'NO' to your question about a fatigue failure. Excessive manoeuvre loading beyond the design strength of the aircraft will usually be a single application causing an' overload' failure as against 'fatigue' which normally requires thousands of load cycles.
One difficulty I had with the TVC type of overload failure is that when the aircraft breaks up, it is in a time scale of seconds. AOM flew for approximately 15 minutes after reporting loss of control. The Indonesian Viscount PK-IVS with springtab-flutter- fatigue causal factors flew for around 20 minutes from calling Mayday to crashing.
I have always regretted that the Irish Viscounts were not fitted with Flight Data and Cockpit Voice Recorders as were in the Australian aircraft at that time. Although early simple devices, they would have almost certainly answered all questions of altitude, speed, flutter and loading and narrowed down the causal factors. However.....
Hope this is of some interest to you
regards. Colin Torkington."
The question was asked of Colin because one of the findings in the 1970 Investigation stated " There is evidence which could be construed as indicative of the possible presence of another aircraft or airborne object in the vicinity which, by reason of collision, or by its proximity causing an evasive manoeuvre to be made, or by its wake turbulence, might have been the the initiating cause of an upsetting manoeuvre resulting in the Viscount entering a spin or spiral dive," (Page 20 para 2.2.2.1. 12)

[Spotlight]

Possibly unrelated:

However, a Viscount crashed and killed all on board after take-off from Sydney in the late fifties. Butler Air Transport (BAT). Severe thunderstorms were present.

Strongly suspected by people close to the operation (but not adressed in the subsequent official report), was that the overhead CB and switch panel unlatched and swung down on the hinges, sconning the pilots.

411. Ansett had a check captain who put a Friendship on its roof at Launy Tasmania many moons ago. Pitch Lock on descent, overcooked approach with (late) attempted go-round---or something???

The big wheel was given a spin and he was----------PROMOTED.

[BEagle]

spring tab-flutter- fatigue

This sounds a highly likely cause - perhaps leading to loss of control and a spin?

How was recovery from those steep dives effected? Was pitch trim used in an attempt to assist with heavy control forces?

One wonders whether the pitch circuit, rather than empennage, was subjected to loads beyond those it was designed to cope with?

Repeatedly playing Stukas with a Viscount is unlikely to have been beneficial to aircraft fatigue.

[llanfairpg]

Fergus

Was it AL policy to do this sort of training, or was it just one cavalier training captain playing to the gallery?

What sort of G forces do you estimate were involved in these 'pull ups' and am I right in thinking the Viscount would not have been certified to more than about 2.5 positive?

Were renewals done in the simulator and if not were these sort of manoeuvres repeated on base checks?

[Just a spotter]

Don't forget that less than 12 months before hand, Aer Lingus lost a sister Viscount 803 to EI-AOM (cn 178)

On June 22, 1967, EI-AOF (cn 176) crashed while on a training flight near Ashbourne in North County Dublin (a few kilomometers north of EIDW). The aircraft went into a spin from a low altitude and impacted the ground killing all 3 on board. The accident report blamed corrision around the tail and higlighted issues with the then Aer Lingus maintenance procuedures.

JAS

[411A]

411. Ansett had a check captain who put a Friendship on its roof at Launy Tasmania many moons ago. Pitch Lock on descent, overcooked approach with (late) attempted go-round---or something???

The big wheel was given a spin and he was----------PROMOTED.

Par for the course, in my experience.

It has always amazed me that some folks want to do with the aeroplane something for which it was not designed...or, to put it another way, how hard is it to actually fly the airplane according to the manufacturers instructions?
From some of the accident statistics...apparently, quite a few.
These few folks are right and truly...silly fools.
Or, if you like, a**holes.

[narnia]

Viscount Dives

The two sharp diving training manoeuvres seemed to be part of standard initial conversion. I have no reason to think they were ex curricular, but we never did anything like this again in subsequent training.

The rapid descent from apx 13000' was probably part of a normal decompression exercise, although it certainly involved the non-normal stresses of initial sharp nosedown control column push to at least 45 degrees until maximum operating speed was achieved for descent. The level out would have been less stressful than the initial descent but still more than a normal level out. This exercise definitely took place on AOM days before the crash and I reported that to the second investigation. I have no knowledge of the training details of the others on our conversion course.

As for the sudden dive at the runway from 1000' this was certainly a dramatic manoeuvre with, again, initial heavy and sudden push for nose down after closing throttles to maintain speed control and a final pull up before landing sharper than any normal approach forces. But it would not have involved excessive G anywhere near limit.

[DH106]

But it would not have involved excessive G anywhere near limit.

Yes, but of course it's possible that the elevators & associated tabs etc. could be pushed closer to their ultimate limits than perhaps evident by the aircraft's overall G loading.... And when you combine that with the issue of whether these components had grossly exceeded their "safe life" as I believe was inferred in the recent "Tradgedy At Tuskar Rock" book (and not mentioned in the 1970 report) then perhaps it was just an "accident waiting to happen".

It does sound like tab flutter is the most likely cause of -AOM's crash. As 383656 points out above - comparison with the PK-IVS crash is very interesting, although the final mode of crash is different with -IVS finally losing an elevator after prolonged tab flutter, the crew losing control and the Viscount diving to the ground.

[383656]

Viscount Crash off Tuskar Rock

I have been endeavouring to obtain a reasonable explanation as to why nobody on board EI-AOM was wearing a lifejacket even though the a/c was flying in a disabled condition for approx. 30 minutes (according to the 2002 International Team Study)...can you help.

[Flightwatch]

Glide Approach

I remember my own base training in the UK on the Viscount 700 in 1967 where the same manoeuver was required on finals. As far as memory serves it was done from 1500' and when the threshold disappeared from view the throttles were closed and full (47 deg?) flap was selected - a setting that could only be achieved when the throttles were closed - they automatically retracted to the penultimate setting if power was applied. The aiming point was the mid point of the runway and a flare started very early. I can only assume that was part of the required test for the 1179. In my case the aircraft then soldiered on for another 3 years before ultimately being scrapped so it appeared to do it no harm.

I subsequently flew the 800 too but was not required to repeat the exercise on the final base check for that model. (We had the use of the BEA simulator for the conversion and most of the airwork was done on that.)

[talent]

Just a spotter,
WAnt to pull you up on your reasons for the crash of EI-AOF June 22, 1967. This was, of course, the Aer Lingus Viscount on a training flight.

"The accident report blamed corrision around the tail and higlighted issues with the then Aer Lingus maintenance procuedures."

According to my source on this crash, Michael O'Toole's excellent book on Irish air crashes, Cleared for Disaster, the probable cause was the possible incapacitation of the training captain, the only qualified pilot aboard, perhaps due to a heart attack, and the inability of the trainees to find the airport in the overcast conditions, and to land the airplane. The main safety recommendation was that a second qualified pilot should always accompany the training captain.

I know corrosion was examined in the Tuskar Rock crash (the subject of this thread) but this has always been an inconclusive investigation.
Talent