Trident autothrust system and autoland
Join Date: Jan 2008
Location: UK
Posts: 116
Likes: 0
Received 0 Likes
on
0 Posts
I hope this link works. it is to the AAIB report into PI. Have a look at page 39 - the Fox Hotel incident.
Air Accidents Investigation: 4/1973 G-ARPI
Air Accidents Investigation: 4/1973 G-ARPI
SLAST
I spent three days researching the testimonies in the BA museum and made a FOI request to the AAIB.
I have written a biography but due to advice from counsel have put publishing it on hold.
Cunningham's testimony I have read in full and there is a reference to him in the accident report.
As has been pointed out we flew a different noise abatement procedure than that recommended by Davies who was the ARB test pilot , it is in handling the big jets.
There is also a file on his testimony which I do believe is not mentioned in the official report. I missed reading this which I regret and at the time I didn't understand the significance that he isn't mentioned in the report.
The report states that there was a baulk (or interlock) fitted between the levers as there was a theory put forward that if the down selection wasn't made correctly then the droop could automatically move when the flap lever is selected up .
I remember playing with the levers with the engines off and realised it was balderdash - the theory is in the report.
There are several opt out clauses on FOI which the AAIB used after they had retrieved the files for me.
Two important questions they couldn't answer under these constraints, one was whether my letter about our training had been submitted by FM to the inquiry.
But I had a very interesting conversation from one of the accident inspectors.
The main points of this conversation for this forum were his distancing himself and the AAIB from the inquiry conclusions and that the simulator flying characteristics were markedly different those of the aircraft.
The other interesting testimonies were George Childs who had quizzed me on what to do with a stall warning and had tried to get management to introduce a correct stall recovery procedure, Evans, Holloway and one training captain who said he had interviewed numerous co pilots who, to a man, had recounted a stall recovery procedure which was rather different to that which I had been taught and was in my flying procedures - those of us on the fleet at the time will know what I am getting at.
Hobo
Sorry I will not go into much detail on the forum but somewhere in the inquiry report it says words to the effect that co pilots were provided to ASSIST the Captain as the Trident was to complicated to be operated by one pilot.
Contrary to what was stated in equally sharing the flying, I achieved around one leg in five and when I was initially P2 only I flew EIGHTEEN sectors RHS without being allowed to attempt a landing.
And if you really want to look at the BEA field of influence - I joined the week the Vanguard dug a hole near Ghent - this was followed by another six or seven aircraft in my 6 years in BEA.
All bar one were 100% our fault - except for Zagreb although the report stated that if the crew had looked out then the accident might have been avoided.
Other prangs were the viscount flew into cloud wiv hard centre.
Cyprus T2 - low slow during training - became XM.
Two 707s .
Bilbao 1E.
I left BEA in 1978, the accidents didn't initially - so it wasn't my fault your honour.
BOAC didn't destroy anything during this period.
I owe a huge amount to some of the ex national service pilots and Hamsters on the Trident and without their nurturing I would have never successfully completed my transition on the Iron Duck.
I spent three days researching the testimonies in the BA museum and made a FOI request to the AAIB.
I have written a biography but due to advice from counsel have put publishing it on hold.
Cunningham's testimony I have read in full and there is a reference to him in the accident report.
As has been pointed out we flew a different noise abatement procedure than that recommended by Davies who was the ARB test pilot , it is in handling the big jets.
There is also a file on his testimony which I do believe is not mentioned in the official report. I missed reading this which I regret and at the time I didn't understand the significance that he isn't mentioned in the report.
The report states that there was a baulk (or interlock) fitted between the levers as there was a theory put forward that if the down selection wasn't made correctly then the droop could automatically move when the flap lever is selected up .
I remember playing with the levers with the engines off and realised it was balderdash - the theory is in the report.
There are several opt out clauses on FOI which the AAIB used after they had retrieved the files for me.
Two important questions they couldn't answer under these constraints, one was whether my letter about our training had been submitted by FM to the inquiry.
But I had a very interesting conversation from one of the accident inspectors.
The main points of this conversation for this forum were his distancing himself and the AAIB from the inquiry conclusions and that the simulator flying characteristics were markedly different those of the aircraft.
The other interesting testimonies were George Childs who had quizzed me on what to do with a stall warning and had tried to get management to introduce a correct stall recovery procedure, Evans, Holloway and one training captain who said he had interviewed numerous co pilots who, to a man, had recounted a stall recovery procedure which was rather different to that which I had been taught and was in my flying procedures - those of us on the fleet at the time will know what I am getting at.
Hobo
Sorry I will not go into much detail on the forum but somewhere in the inquiry report it says words to the effect that co pilots were provided to ASSIST the Captain as the Trident was to complicated to be operated by one pilot.
Contrary to what was stated in equally sharing the flying, I achieved around one leg in five and when I was initially P2 only I flew EIGHTEEN sectors RHS without being allowed to attempt a landing.
And if you really want to look at the BEA field of influence - I joined the week the Vanguard dug a hole near Ghent - this was followed by another six or seven aircraft in my 6 years in BEA.
All bar one were 100% our fault - except for Zagreb although the report stated that if the crew had looked out then the accident might have been avoided.
Other prangs were the viscount flew into cloud wiv hard centre.
Cyprus T2 - low slow during training - became XM.
Two 707s .
Bilbao 1E.
I left BEA in 1978, the accidents didn't initially - so it wasn't my fault your honour.
BOAC didn't destroy anything during this period.
I owe a huge amount to some of the ex national service pilots and Hamsters on the Trident and without their nurturing I would have never successfully completed my transition on the Iron Duck.
Last edited by blind pew; 16th Dec 2010 at 21:08.
Flap retraction after take off - yes I witnessed that as well.
Even got to Burnham off 27 left at 365 knots and three grand.
Re high speed cruise / wing performance.
The Trident one approached around 30 knots faster than the DC 8 - I know as had to go around on my annual route check when an Eitie didn't understand " keep 180 knots to the outer marker" and reduced to an approach speed 30 knots below our minimum.
I believe that we rotated at a comparatively high speed due a very dirty wing and lots of drag. Don't forget that the T1 had a rather crude droop compared to the T2.
The clean wing was very thin - I believe that MMO was .92 but later reduced to .885 - therefore power wasn't a problem in level flight.
We used to race the Swiss Coronados (which were equally hot) into LHR - best trick was to get underneath them and match their speed.
Happy days.
Even got to Burnham off 27 left at 365 knots and three grand.
Re high speed cruise / wing performance.
The Trident one approached around 30 knots faster than the DC 8 - I know as had to go around on my annual route check when an Eitie didn't understand " keep 180 knots to the outer marker" and reduced to an approach speed 30 knots below our minimum.
I believe that we rotated at a comparatively high speed due a very dirty wing and lots of drag. Don't forget that the T1 had a rather crude droop compared to the T2.
The clean wing was very thin - I believe that MMO was .92 but later reduced to .885 - therefore power wasn't a problem in level flight.
We used to race the Swiss Coronados (which were equally hot) into LHR - best trick was to get underneath them and match their speed.
Happy days.
Join Date: Jan 2001
Location: UK
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Aileron Drag
Not wanting to go too far off topic, but the DC10 system, whilst better, was not foolproof, as a couple of stalling incidents in the mid 90s showed. One of these was on approach, when flap was selected out, but not the slats. It needed a bit of wear and tear on the levers and linkage, but it could, and did, happen.
Hard to believe, I know, especially if you know the linkage between the two levers, but I was on the fleet at the time, and watched in amazement as a TCP showed me exactly how the two levers had been (inadvertently) separated on one of the incident flights. Like watching a conjuring trick, you know what you've seen, but you don't believe it!
I believe Boeing got it right, with the single lever concept.
Regards
Trident Sim
The DC10 had a mechanical link between the trailing/leading edge levers, so that both levers moved together, and only the last selection would retract the slats. The system was (IMO) foolproof.
Hard to believe, I know, especially if you know the linkage between the two levers, but I was on the fleet at the time, and watched in amazement as a TCP showed me exactly how the two levers had been (inadvertently) separated on one of the incident flights. Like watching a conjuring trick, you know what you've seen, but you don't believe it!
I believe Boeing got it right, with the single lever concept.
Regards
Trident Sim
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
Some 727 pilots worked their way round that by popping CBs though, so no system is completely foolproof.
Join Date: Jan 2005
Location: France
Posts: 2,315
Likes: 0
Received 0 Likes
on
0 Posts
Following this with great interest, even though the "Gripper" was 'before my time'.
This of course calls for that classic remark:
"It's so difficult to make anything fool proof, because fools are so damn ingenious..."
CJ
"It's so difficult to make anything fool proof, because fools are so damn ingenious..."
CJ
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
I have a very strong belief that the avionics of your beloved bird owed a great deal to the advances made on the Trident - I understand that Lockheed later poached a lot of the avionics guys to work on the Tristar too.
Join Date: Jan 2005
Location: France
Posts: 2,315
Likes: 0
Received 0 Likes
on
0 Posts
I'd be the last one to restart the "Smiths/Elliotts war" of the time on a forum and a topic like this, a subject so much better discussed today over a pint at the local!
But it's a subject worth discussing, and I'll be only too pleased to see other input!
For me, there are two key differences between Trident and Concorde.
The first one is, that Smiths went for the "triplex" solution, with three computers continously "talking to each other", and checking that all three were "reading from the same song sheet".
If they didn't agree, no autoland.
Elliott, who did the VC10, and then Concorde (with SFENA), went for the alternative "duplex monitored" solution, with two computers, where each of the two was effectively two computers in one, with a "command" and a "monitor" channel being compared continously.
If the two halves didn't agree... end of story : the computer would disconnect and hand over to the other one, which up to then would have been a "hot" standby.
Otherwise, the two computers basically did not "talk to each other".
BITE (built-in test) was used to assure that both computers were still serviceable just before committing to an autoland, thereby reducing the 'time at risk' of a common failure to a couple of minutes, and the resulting risk of such a failure to "highly improbable".
The other difference was simply a matter of age.
The Trident system came into being before the arrival of integrated circuits.
Now, I've never had a real opportunity to dive into the Trident electronics, but going by other systems from the same period, I would expect it to be full of things like magnetic amplifiers, transistor-based operational amplifiers, and transistor and relay type logic.
Concorde happened just at the time of the arrival of the first integrated operational amplifiers and the first integrated logic circuits.
At that time, integrated circuit development was going so fast, that the avionics on the prototypes, the preproduction aircraft and the production aircraft basically ended up using three succesive generations of integrated circuits..... (for the conoscienti here... think 165, 709 and LM101 for the opamps, and RTL, DTL and TTL for the logic).
So, to make sure we agree... the Trident and Concorde both, certainly profited hugely from the pioneering work of the BLEU, and the experiments with the Lear system on the Caravelle.
But, IMO, they diverged afterwards.
CJ
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
I understand that Lockheed later poached a lot of the avionics guys to work on the Tristar too.
Smiths made the very first operational automatic landing system - as fitted to the RAF Victors and Vulcans. It was a different system to the civilian ones though.
Last edited by Dan Winterland; 17th Dec 2010 at 10:36.
Join Date: Apr 2010
Location: New Forest
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
Fairly Early Flap Retraction
Indeed! When fairly new on type, I was pre-warned, but even so slightly alarmed when a well known Captain from a far flung part of the Empire insisted on flap being fully retracted by 500ft. Interesting and exciting, but not now part of the aviation scene. Getting old.
Prober
Prober
Join Date: Jan 2009
Location: Somewhere over the rainbow
Posts: 73
Received 0 Likes
on
0 Posts
Maybe dumb question but was the Trident the first aircraft to have wing leading edge lift devices (slats or droops or whatewver you call them)?
Dont recall noticing them on other aircraft of the era or earlier that I flew on like Caravelle, comet etc.
Dont recall noticing them on other aircraft of the era or earlier that I flew on like Caravelle, comet etc.
Join Date: Jan 2005
Location: France
Posts: 2,315
Likes: 0
Received 0 Likes
on
0 Posts
But wing leading edge devices as such go back to WWII, and probably even pre-war. Some Messerschmitts come to mind, and the Fieseler Storch STOL, but the list is much longer.
CJ
Join Date: Apr 2007
Location: Dartmouth, Devon U.K.
Age: 90
Posts: 162
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Nov 2007
Location: Northampton
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
Indeed! When fairly new on type, I was pre-warned, but even so slightly alarmed when a well known Captain from a far flung part of the Empire insisted on flap being fully retracted by 500ft. Interesting and exciting, but not now part of the aviation scene. Getting old.
Prober
Prober
Join Date: Aug 2005
Location: London
Posts: 78
Likes: 0
Received 0 Likes
on
0 Posts
Re earlier question on what changes were made to the flap and slat/'droop' system post PI, the story isn't quite right. There always was a flap/droop balk so that if the flaps were not up, the droop lever could not be moved inadvertently or otherwise. What killed PI was that having moved the flaps up, there was nothing to stop anyone raising the droop at a ludicrously low speed. The claim that a single lever would have prevented PI is questionable - it is just as easy to retract slats early with one lever as two, you just have to forget what you are doing, as someone just proved recently with an A320. The Stan Key Memorial Mod was to add a speed balk to the slat/droop lever, set, if I recall, at a nominal 208 kt.
An even earlier post asked how it flew, thinking it might be difficult. Actually as Pete Mcclelland and others have said it was a doddle once a whole lot of cr*p acquired in early training was ignored and people went back to treating it like an aircraft. No thrust/pitch couple, little asymmetric yaw, super crisp ailerons, immaculate High Mach behaviour, and a 'classic' trim system that left you knowing exactly where you were. The only inconvenience was the position of the thrust levers (sorry, throttles) which were indeed a bit of a stretch, but that didn't stop the final iteration of Trident handling being just like any other aircraft, with the handling pilot handling (gasp!) his own throttles.
Finally despite rumours to the contrary the aircraft was not speed unstable on the approach, Vat was above min drag at the appropriate flap setting, and experienced hands could carry out an ILS hardly moving a muscle. Nothing since has come close (though I only encountered the splendid L1011 in the sim so perhaps there is room for argument, 411A).
An even earlier post asked how it flew, thinking it might be difficult. Actually as Pete Mcclelland and others have said it was a doddle once a whole lot of cr*p acquired in early training was ignored and people went back to treating it like an aircraft. No thrust/pitch couple, little asymmetric yaw, super crisp ailerons, immaculate High Mach behaviour, and a 'classic' trim system that left you knowing exactly where you were. The only inconvenience was the position of the thrust levers (sorry, throttles) which were indeed a bit of a stretch, but that didn't stop the final iteration of Trident handling being just like any other aircraft, with the handling pilot handling (gasp!) his own throttles.
Finally despite rumours to the contrary the aircraft was not speed unstable on the approach, Vat was above min drag at the appropriate flap setting, and experienced hands could carry out an ILS hardly moving a muscle. Nothing since has come close (though I only encountered the splendid L1011 in the sim so perhaps there is room for argument, 411A).
Join Date: Jan 2005
Location: France
Posts: 2,315
Likes: 0
Received 0 Likes
on
0 Posts
[Tiny O/T...]
Vat? Wot's dat?
Two seconds on Google.
It's Velocity At Threshold, and merely a term I personally wasn't familiar with.
Never too old to learn....
[End O/T]
CJ
Vat? Wot's dat?
Two seconds on Google.
It's Velocity At Threshold, and merely a term I personally wasn't familiar with.
Never too old to learn....
[End O/T]
CJ
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
Nothing since has come close (though I only encountered the splendid L1011 in the sim so perhaps there is room for argument, 411A).
A pilots dream...with dual/dual (not triplex) autoland thrown in.
Join Date: Jan 2009
Location: Somewhere over the rainbow
Posts: 73
Received 0 Likes
on
0 Posts
Reluctant to let this thread die as I have enjoyed reading the insights into this interesting aircraft (as have others judging by the number of posts) so here goes with another (naive) query.
The Trident had leading edge slats whereas I believe that the 1-11 had a fixed leading edge. Was the 1-11 wing design that much more efficient than Trident or was it simply a power:weight factor?
The Trident had leading edge slats whereas I believe that the 1-11 had a fixed leading edge. Was the 1-11 wing design that much more efficient than Trident or was it simply a power:weight factor?
Join Date: Apr 2005
Location: Stockholm Sweden
Age: 74
Posts: 569
Likes: 0
Received 0 Likes
on
0 Posts
The Trident had leading edge slats
But for us engineers, very difficult to make it work properly. Rigging it after a component change took 8 hours.