BAC One-Eleven crash on test flight. Deep Stall
Gnome de PPRuNe
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 60
Posts: 12,600
Received 277 Likes
on
153 Posts
One of the prototype Canadair Challengers was lost after a deep stall related crash.
Challenger #1001
Mind you, that was only 40 years ago.
Trident 1 G-ARPY at Felthorpe?
Challenger #1001
Mind you, that was only 40 years ago.
Trident 1 G-ARPY at Felthorpe?
One of the prototype Canadair Challengers was lost after a deep stall related crash.
Challenger #1001
Mind you, that was only 40 years ago.
Trident 1 G-ARPY at Felthorpe?
Challenger #1001
Mind you, that was only 40 years ago.
Trident 1 G-ARPY at Felthorpe?
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.
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).
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=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.
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.
Last edited by POBJOY; 28th Aug 2020 at 07:49.
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.
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.
Wisley incident
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.
Last edited by POBJOY; 2nd Sep 2020 at 22:35.
Join Date: Aug 2017
Location: South
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
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?
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?
Last edited by Bagheera S; 3rd Sep 2020 at 12:42.
Join Date: Aug 2017
Location: South
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Company pressure
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.
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.
Last edited by POBJOY; 3rd Sep 2020 at 17:06. Reason: content
"Mildly" Eccentric Stardriver
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)
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...
Gnome de PPRuNe
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 60
Posts: 12,600
Received 277 Likes
on
153 Posts
Wasn't there an abandoned idea to fit Concordes 001/002 with ejection seats? Very vague recollection... where's my Trubshaw?
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).
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).
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
According to Trubshaw’s book, when the hatch was fired on the 1-11 it was too close to the ground already.
See: Testing VC10s
According to Trubshaw’s book, when the hatch was fired on the 1-11 it was too close to the ground already.