BAC One-Eleven crash on test flight. Deep Stall [Archive]

Judd

23rd Aug 2020, 08:47

https://www.baaa-acro.com/crash/crash-bac-111-200ab-chicklade-7-killed

Because this tragic accident occurred decades ago, few of todays airline pilots would have been aware of it. It is certainly well worth revisiting the accident report; particularly pilots currently operating T-Tail types.

DaveW

23rd Aug 2020, 10:46

I visited the crash site memorial a couple of months ago.

Very moving, especially with test flights out of Boscombe taking place overhead at the time.

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/533x960/83284803_2923944451015051_2923673320303886336_o_f81e2ba25110 be4499e78a232286d7216fd28431.jpg

Pilot DAR

23rd Aug 2020, 12:52

This:

https://www.aerosociety.com/news/audio-the-d-p-davies-interview-on-testing-the-comets-boeing-707-britannia-brabazon/

And other podcasts of interviews of Mr. Davies (kindly linked to me by another PPRuNer) have fascinating discussions of the stall testing of these types. Very well worth the listen!

DaveReidUK

23rd Aug 2020, 22:25

Because this tragic accident occurred decades ago, few of todays airline pilots would have been aware of it.

I suspect that most pilots of T-tailed aircraft know why they have a stick-pusher.

Timmy Tomkins

24th Aug 2020, 15:04

oldchina

26th Aug 2020, 11:29

1978 comments from Jock Bryce, from the One-Eleven website:

"All I could think of was that we had to tell those seven girls, the wives of the crew, before they heard it on the one o’clock news. But what could we tell them, since we had no definite news of the crew? I knew we couldn’t telephone them – we would have to go and see them. I arranged for each of the wives to have an individual visitor and meanwhile, I pressed for further information on the casualties. I had had no more when I heard the crash announced on the one o’clock news.

By 1.15 I had received the confirmation I dreaded – that all seven of the crew had been killed. When I rang Sir George Edwards I only got one sentence from him. “Never mind the plane,” he said, “look after those girls.”

ex-cx

26th Aug 2020, 14:12

I wonder what would have happened aerodynamically, if they had dropped the rear air-stairs...... if indeed they could be dropped in that flight regime??

teeteringhead

26th Aug 2020, 14:59

Is it true - or just urban myth - that the TPs cooly transmitted their vain recovery efforts all the way down, to help further investigation/prevention?

B2N2

26th Aug 2020, 15:53

Haraka

26th Aug 2020, 17:25

Is it true - or just urban myth - that the TPs cooly transmitted their vain recovery efforts all the way down, to help further investigation/prevention?
I believe so.
The killer was that the "all flying" tailplane was servo tab controlled ( a bit like the Britannia's ailerons) i.e. the pilot had no direct link to the flying surface which basically just flew in the breeze. Lithgow went through a series of actions which he calmly recorded. These included applying max power, frustrated by the rate of descent causing the intakes to be stalled. There were a number of my Father's associates on board.
BAC sent a team across to tbe USA to explain to such as Douglas what went wrong.

POBJOY

26th Aug 2020, 18:42

Very good coverage and investigation results in Brian Trubshaws book Test Pilot.
No doubt lack of fully powered elevator, and poss lack of appreciation of consequence of exceeding AoA limits rather caught out BAC with this.
IN fact industry as a whole was caught out with the T Tail stall situation as the Trident showed even after going in to public service.
Also Vickers had already T Tail experience with the VC10 which had not surprised anyone with its low speed handling at that stage.
As part of the ongoing 111 investigation trials were carried out on the VC10 with relation to airflow around the tail area at low speed.
It appears that the four engine configuration with associate wider engine beams provided an extra 'low set tailplane effect' on the 10 which helped to prevent pitch up.
Also the prototype 111 was not fitted with an emergency tail chute although the replacement test machine was.
Trubshaws book is really his Concorde story, but the earlier years of developing large machines including the Valiant, Viscount, Vanguard, 111.and 10 are a fascinating document in their own right, at a time when computers were not quite the slide rule replacement they became.

A37575

27th Aug 2020, 05:06

The killer was that the "all flying" tailplane was servo tab controlled ( a bit like the Britannia's ailerons) i.e. the pilot had no direct link to the flying surface which basically just flew in the breeze.
I recently read an accident report to a similar high tail type where the elevator used servo-tabs. I am unsure what type but fancy it may have been a DC9 or similar design. When the crew checked the flight controls before takeoff they all seemed to work normally. Except the only problem was there was no correlation between control wheel operation and elevator. Being servo-tab operated the elevator itself doesn't move if the aircraft is on the ground.

When the pilot pulled back to rotate nothing happened and the aircraft stayed on the deck. I forget the result but I think an abort was made too late to prevent the accident.

The cause of the problem started with high winds when the aircraft was parked overnight. The winds affected one elevator and forced it against its stops (?) and caused damage such that it wasn't connected anymore and merely floated free. It was not possible to see the problem during the preflight walk-around inspection. The other elevator was not affected but on rotation it didn't have enough lifting force to lift the nosewheel on its own. All the while the damaged elevator simply floated free during the takeoff roll. .

DaveReidUK

27th Aug 2020, 06:44

I recently read an accident report to a similar high tail type where the elevator used servo-tabs. I am unsure what type but fancy it may have been a DC9 or similar design. When the crew checked the flight controls before takeoff they all seemed to work normally. Except the only problem was there was no correlation between control wheel operation and elevator. Being servo-tab operated the elevator itself doesn't move if the aircraft is on the ground.

When the pilot pulled back to rotate nothing happened and the aircraft stayed on the deck. I forget the result but I think an abort was made too late to prevent the accident.

The cause of the problem started with high winds when the aircraft was parked overnight. The winds affected one elevator and forced it against its stops (?) and caused damage such that it wasn't connected anymore and merely floated free. It was not possible to see the problem during the preflight walk-around inspection. The other elevator was not affected but on rotation it didn't have enough lifting force to lift the nosewheel on its own. All the while the damaged elevator simply floated free during the takeoff roll. .

The above sounds like the Ameristar MD-83 at Ypsilanti in March 2017, though it would be more accurate to say that the elevator was completely jammed rather than able to float freely.

NTSB investigation report here: Runway Overrun During Rejected Takeoff (https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1901.pdf)

oldchina

27th Aug 2020, 09:35

I always thought the original design had direct manual (cable) controlled elevators

DaveReidUK

27th Aug 2020, 10:33

I always thought the original design had direct manual (cable) controlled elevators

Yes, the DC-9/MD-80 has manual pitch control, although it doesn't move the elevator directly, but moves the control tabs (or servo tabs, depending on which side of the Atlantic you're from).

POBJOY

27th Aug 2020, 12:58

Surprising that BAC allowed this situation to go so far as it did, when other TP's who had flown the machine had already made adverse comments with regard to elevator authority and its lack of stability on landing. Even after the subsequent machines were modified yet another AC was written off at Wisley when the aircraft developed PIO on landing.
One would have thought the company took notice of what their TP's said !!!!

blind pew

27th Aug 2020, 14:00

DaveReidUK

27th Aug 2020, 14:08

Iirc there was a hydraulic boost? Fitted to augment elevator control at low speeds..think it operated with full forward stick. The tailplane problem due to high winds was known and was clearly visible if you looked at it during walk around.

There was indeed a hydraulic boost, to provide more AND pitch than the servo tab could produce. See the 3 pages of description of the elevator control system in the accident investigation report I linked to in my previous post.

tonytales

27th Aug 2020, 18:44

Became a maintenance instructor in 1966 anbd attended DC9-10 series school. Douglas was very aware of the problem. The DC9 did not have a "elevator boost control". Instead there was a "disagreement mechanism" so if the piloit was pushing the column forward but the elevators wer "UP", the hydraulic actuator operated and pushed the elevators "DOWN". In any noprmal flight configuration, the flying tabs did the work and the hydraulic actuator just went along for the ride.
Did the British authorities requie a "stick pusher" for the DC9?
DC9 had also installed "vortillon fences" under the inboard bottom of the wing and strakes up forward on the fuselage, all intended to aleviate deep stall tendencies.
I actually saw the TIA DC8 at JFK that had jammed elevators due to some tarmac paving breaking up and pieces flying up and lodging in the gap between stabilizer and elevator. I heard loud engine stalls and looked out the side window of a B727 I was troubleshooting. Saw the aircraft in an almost vertical position aand then fall off and go right down. Giant eruption of flame and smoke followed. Ghastly sight.

tdracer

27th Aug 2020, 18:44

Back during my college days, we had a professor who talked about this BAC 111 deep stall crash (I'm guessing it was an Aero Stability and Control class but it's been ~45 years).
Anyway, after describing the crash deep stall characteristics that caused it, he stated there had been another flight test crash of a T-tail designed aircraft where they were simulating an electrical power failure that disabled the stick-pusher and inadvertently got into a deep stall. He even elaborated that they tried various tricks (that had been brainstormed after the subject crash) in an effort to get out of the deep stall, but to no avail. But looking on the internet - while I can find other deep stall crashes of T-tail aircraft - I can't find one that fits his description of happening during flight testing.
Anyone know what he may have been talking about?

treadigraph

27th Aug 2020, 18:52

tdracer

27th Aug 2020, 21:35

One of the prototype Canadair Challengers was lost after a deep stall related crash.

Challenger #1001 (http://www.check-six.com/Crash_Sites/Canadair-CGCGRX.htm)

Mind you, that was only 40 years ago.

Trident 1 G-ARPY at Felthorpe (https://en.wikipedia.org/wiki/1966_Felthorpe_Trident_crash)?
Definitely not the Challenger - that happened three years after I graduated and was well into my Boeing career.
Might well be the Trident...

DaveReidUK

27th Aug 2020, 22:22

Might well be the Trident...

Not a simulated electrical power failure, but the flight test being carried out on G-ARPY required the pilot to verify that the aircraft would remain relatively wings-level during a stall, which necessitated disabling the stall warning and recovery system.

tdracer

27th Aug 2020, 23:30

Not a simulated electrical power failure, but the flight test being carried out on G-ARPY required the pilot to verify that the aircraft would remain relatively wings-level during a stall, which necessitated disabling the stall warning and recovery system.
Yea, that sounds like what my prof described - 45 year old memory and such but I'm sure he said they'd intentionally disabled the protections as part of the flight test. My memory is that he said it was another BAC 111, but that could be either faulty memory on my part, or a simple miss-statement or miss-understanding on his part (given they were both British built aircraft).

DaveReidUK

28th Aug 2020, 06:45

My memory is that he said it was another BAC 111, but that could be either faulty memory on my part, or a simple miss-statement or miss-understanding on his part (given they were both British built aircraft).

Strangely enough, I saw a link recently (can't remember where) asserting that two One-Eleven prototypes were lost in deep stall events, which is demonstrably nonsense, so there may be a minor urban myth at work here.

Or there may be some confusion with an incident in August 1964 involving an early production aircraft which was used prior to delivery to investigate deep stalls and belly-landed on Salisbury Plain after the stall recovery parachute had failed to jettison. The aircraft was repaired and delivered to the customer the following year.

POBJOY

28th Aug 2020, 07:37

[QUOTE=DaveReidUK;10872389]Strangely enough, I saw a link recently (can't remember where) asserting that two One-Eleven prototypes were lost in deep stall events, which is demonstrably nonsense, so there may be a minor urban myth at work here.

Or there may be some confusion with an incident in August 1964 involving an early production aircraft which was used prior to delivery to investigate deep stalls and belly-landed on Salisbury Plain after the stall recovery parachute had failed to jettison. The aircraft was repaired and delivered to the customer the following year.[/QUOTE
easy.
This incident is also recorded in the BT book except that TP in question did not actually attempt to jettison the chute and it 'forced landed' rather than stalled in. What interested me in this incident was the fact that the aircraft was not written off in this episode which must say something for its overall structural design/integrity. In fact the detail that BT goes into with relation to the amount of effort required to get the 111,Vanguard,and the 10 through stalling tests is a 'books worth' in its own right, and makes the Concorde part look almost easy by comparison, although by then computers and the simulator had reduced empirical flight risks considerably. However as we have seen with the B 737 Max scenario one ignores the 'actual' Aircrafts behaviour at your peril.

Jhieminga

28th Aug 2020, 08:29

Strangely enough, I saw a link recently (can't remember where) asserting that two One-Eleven prototypes were lost in deep stall events, which is demonstrably nonsense, so there may be a minor urban myth at work here.

Or there may be some confusion with an incident in August 1964 involving an early production aircraft which was used prior to delivery to investigate deep stalls and belly-landed on Salisbury Plain after the stall recovery parachute had failed to jettison. The aircraft was repaired and delivered to the customer the following year.
I agree that it most likely refers to the August 1964 accident that left G-ASJD in a field, fortunately without any loss of life. This is also covered in books like Stephen Skinner's title about the 1-11 (this one (https://amzn.to/32CrjXo)) and Sir George Edwards' biography (https://amzn.to/2YKs4wG). Having to explain to the customers why a another 1-11 prototype had crashed (that was still the first impression) was a challenge. Test pilot Peter Baker had previously had to stream a tail parachute in a Victor after an uncontrollable pitch up, which left him in a vertical dive. When the 1-11 didn't respond to the elevator like he expected it to, he streamed the chute but did not get the pitch down response that he needed and expected. He continued to descend with the chute streamed and using a combination of full flaps and full power managed to control the rate of descent to allow a belly landing. It wasn't until later that he found out that it wasn't a deep stall.

WB627

28th Aug 2020, 15:39

G-ASJD - https://aviation-safety.net/database/record.php?id=19640820-1

oldchina

2nd Sep 2020, 20:08

So that makes three One-Eleven accidents at the hands of BAC : G-ASHG, G-ASJB and G-ASJD

POBJOY

2nd Sep 2020, 22:24

So that makes three One-Eleven accidents at the hands of BAC : G-ASHG, G-ASJB and G-ASJD

The Wisley incident is dealt with in the BT book. PIO on landing not helped by the 'peculiar' handling as described by BT. This machine had been 'Part modified' with one elevator powered and one as built. Looking back on it now it seems BAC were in denial with the problem at the time, as two of their TP's had expressed concerns about the situation prior to this.
When BT became CTP he was able to input more 'clout' into the system and for those interested in how much effort went into certifying the 10 it is a good read well before he gets on to Concorde.

Bagheera S

3rd Sep 2020, 11:31

Bagheera S

3rd Sep 2020, 13:25

I once worked with a former member of the Vickers flight test department who was there when these fateful events took place. He told me the following which is not in the report;-

Lithgow had picked up some unexpected stall behaviour on early test flights which he felt wouldn’t meet certification requirements. One of the proposed solution was to revise the wing to fuselage incidence which had massive implications for the whole program so was hotly debated. In an effort to make a decision, against impossible time pressures, the assistance Head of Aerodynamics and Design were cleared for a test flight so that decisions could be made on the spot to expand the stalling envelope. My colleague heard the flight test voice recordings;- he said that the during the initial stalls, the two engineers were on the flight deck and could be heard encouraging Lithgow to go a little further in the hope of completing the full BCAR stall demonstration. Ultimately, although close, tragically it was step too far. After this incident company regulations/procedures were changed such that heads of engineering were not allowed to fly on high risk test flights. This was to put an end to ad hoc/peer pressure during flight tests.

POBJOY

3rd Sep 2020, 17:00

There was enormous commercial pressure on both the 111 and the 10 to perform as offered in the 'brochure', and as it happens the 111 was the machine that paid off commercially even after the initial problems, due to offering a quantum leap in jet travel for the emerging holiday markets. The 10 was designed to fit the BOAC routes not suitable for the 707 so rather like the Trident had a built in limitation 'commercially' for the world market against the USA.
Both machines ended up as a class act on their individual merits, however the 111* was better suited for 'stretches' as required where as the 10* gained rather an unfortunate reputation for fuel consumption v px load but was always popular with clients due to low noise levels and ride. BOAC killed off the 10 as the bean counters gave it the thumbs down, but as proved in the long run it required less maintenance than the 707 and the overall costs balanced out. Of course in the end it was easier to extend runway lengths at airports worldwide than build specific aircraft to suit old facilities. It so happens that at Newquay airport one can 'explore' both* these very British machines which were produced as the industry started its decline in that market. It is amazing that decades later commercial pressures saw us with the 737 max, certification fiasco which brings home the magnitude of what is at stake nowadays when you try to short circuit pax safety to sell machines.

Herod

3rd Sep 2020, 18:17

HP Victor XL159 lost to deep stall from an intentionally unusual stall entry configuration while with the A&AEE, on the 23 March 62. I’m unsure as to the specific condition being tested but they certainly tried quite a few ideas in an attempt to get it out of the stall. Crew abandoned aircraft, 3 survived, 2 died.

Pilots John Waterton and "Spud" Murphy ejected, the latter at approx 300'. AEO John Tank survived. The other two rear crew were unable to disconnect their personal equipment connectors (a new type) in time and died in the crash. The Victor descended from 10,000' to ground level in approx 50 seconds. "Spud" later became Ops Director for Air Anglia/Air UK (and my boss)

tdracer

3rd Sep 2020, 18:34

Pilots John Waterton and "Spud" Murphy ejected, the latter at approx 300'. AEO John Tank survived. The other two rear crew were unable to disconnect their personal equipment connectors (a new type) in time and died in the crash. The Victor descended from 10,000' to ground level in approx 50 seconds. "Spud" later became Ops Director for Air Anglia/Air UK (and my boss)
Interesting that they'd installed ejection seats (at least for the pilots) in an aircraft with no military connections. I presume that was a specific mod for flight testing(?).
I know that Boeing has made provisions to allow the flight crew to bail out for the first flights of a new model (such as making a door operable in-flight for egress). I know the first 777 was fueled for the first flight to allow it to divert to Edwards AFB if needed for an emergency landing. But I'm unaware of them ever fitting ejection seats...

Jhieminga

3rd Sep 2020, 19:31

Herod's comment related to the HP Victor, a type with a military connection....

treadigraph

3rd Sep 2020, 19:49

Wasn't there an abandoned idea to fit Concordes 001/002 with ejection seats? Very vague recollection... where's my Trubshaw?

dixi188

4th Sep 2020, 17:42

The One Eleven had an escape chute / tube through the forward freight bay, accessible from the cabin, but on the fateful day in 1963 the hatch would not open due to the air pressure on the outside due to the near vertical flat descent and also possiby due to negative cabin differential.
On later aircraft the hatch was fitted with explosive bolts. ('YDs hatch was blown off in the hangar about 1972 when I was an apprentice at Hurn).
There was also an anti spin/stall recovery parachute assembly ready to be fitted the following week when G-ASHG was due at Hurn for maintenance.

( my father was a flight shed inspector at the time).

oldchina

4th Sep 2020, 18:51

According to Jock Bryce: "The explosive bolts in the forward escape exit had been fired, (but no-one got out) "

Jhieminga

5th Sep 2020, 08:04

When the VC10 prototype got into trouble, the escape hatch was fired but the chute crumpled. Fortunately it wasn’t needed on that flight.
See: Testing VC10s (http://www.vc10.net/Memories/FlightTesting.html#How%20to%20Escape%20from%20a%20VC10)
According to Trubshaw’s book, when the hatch was fired on the 1-11 it was too close to the ground already.

washoutt

5th Sep 2020, 10:00

The F-28 and F-100 also had an escape chute to the side of the aircraft, but fortunately these aircraft did not suffer from deep stall, and the cute was never used. Also, JATO's were installed in the tail to push the nose down. Also never used. Fortunately.

Herod

5th Sep 2020, 17:18

washout: I presume you mean the test aircraft only. Production aircraft certainly not.

BSD

6th Sep 2020, 07:59

I have a feeling East African Airways had a stall related incident (though it may have been a yaw damper Dutch Roll event) on an air test of a VC-10 over the Indian Ocean off the coast of Kenya.

I can't find my copy of "East African - an airline story" by Peter Davies, in which I'm sure he describes it. I believe it came close to a tragic conclusion.

BSD.

washoutt

6th Sep 2020, 09:22

Of course only test aircraft . How do you get 100 pax through a (narrow) chute?

DaveReidUK

6th Sep 2020, 11:44

Of course only test aircraft . How do you get 100 pax through a (narrow) chute?

Come to that, how do you get 100 pax into an F.28 in the first place? :O

Jhieminga

6th Sep 2020, 13:26

You use an F.28 Mk.100.

Edited to add: I had a look through my copy of Peter Davis' book, but couldn't find the VC10 stall incident BSD mentioned. I would be interested to learn more about if you can find the details.

POBJOY

6th Sep 2020, 20:25

The 10 prototype G-ARTA had an eventful early life doing stalling tests for the type. It was on one of these that as BT put it 'All h... broke loose' and he thought they would loose the machine.
Not sure of the sequence but two engines 'rotated' in their mountings causing associated loss of hydraulics and instumentation, one elevator went unstable and all in all it was obviously a very alarming situation. This is the flight where they tried to operate the escape hatch.but when fired the trunking inside collapsed. After slowing down to near the stall speed the elevator calmed down and they were able to 'drop the gear' and return to Wisley. The poor old girl had done hundreds of stalls and was probably lucky to survive.
Survive she did and went into service with BCAL but was severly damaged in a landing accident at Gatwick 28 01 72 never to fly again, no doubt having spent many years in the Aviation eqiv of PTS. I would highly recommend this book to anyone wishing to revisted the time when flight testing had to be done before simulator experience available.