Trident autothrust system and autoland

[ChristiaanJ]

Let's try not to go too much O/T, 'coz this thread is too interesting.
I'm sure there's already another thread (JetBlast probably) with all those jokes.
Anyway, I always thought BEA stood for "Britain's Excuse for an Airline"....

I'm not biased, because I never had the occasion to fly either BEA or the Trident. I regret the latter....
I did fly on the 1-11, though. The very same one that went and got its feet wet off the end of the Corfu runway, one week after I flew on it...

CJ

[Nick Thomas]

I am enjoying reading this thread and have learnt a great deal about the Trident. So thank you all
I flew to Venice from LHR with BA in the summer of 1982. IIRC it was a Trident but am not sure which version. Were BA still flying all 3 versions in 1982?

Regards
Nick

[WHBM]

Originally Posted by Wookey

Just why was the Trident a three pilot flight deck when surely most short haul aircraft of the era had become two crew operations?

I think the first jets with more than two engines which was two crew were the 757/767, introduced some 18 years after the Trident. In fact when the Trident came along there weren't any 2-crew jets at all.

Among the twins, Caravelles were three crew, and even the first 737s had an option of a three crew flight deck, not sure if any were so configured. In the USA, the FAA had an arbitrary upper limit of 80,000 lbs (40 tons) for two-crew operations, which the Trident was well beyond. The first One-Elevens were marginally over this, and not sold in the USA, but it was redesigned as the One-Eleven 400 that came just inside the limit, as did the first short DC9-10s. The restriction was later relaxed when the DC9-30 and 737 came into prospect.

[d71146]

Post 161

BEA= Back Every Afternoon
Well thats how it used to be in days of old.

[Data Dad]

At the risk of thread drift....

WHBM Wrote:

The first One-Elevens were marginally over this, and not sold in the USA, but it was redesigned as the One-Eleven 400 that came just inside the limit,

have to disagree - the intial One-Elevens were series 200 and MTOW was originally 73500lbs later 78500lbs (up to 79 pax) and was operated by Braniff, Mohawk and Aloha in the US. The later -400 was 92000lbs, up to 89pax.

Back to Tridents.... Spent a very enjoyable week or so in 1982 with British Airways as part of my ATCO training, 'flying' the Trident 3 Cockpit Procedures Trainer. That was until we broke it So we rounded off the time getting up at oh-dark hundred to use the full flight sim at Cranebank Also made a number of line-trips on the jumpseat - a late evening Bovingdon Snatch onto 10L was certainly interesting as was watching the flourish with which the crews operated the autopilot.

DD

[Tom355uk]

I think the first jets with more than two engines which was two crew were the 757/767,

AFAIK there has never been either a 757 or 767 with more than two engines.... I believe the first two crew civil airliner with more than two engines would have been the MD11, closely followed by the 747-400.

Mt first ever trip was on a 1-11, operated by Maersk Air UK in BA Landor livery from BHX to BFS in 1995. Unfortunately, only being 10 years old at the time I didn't realise the significance of this beautiful machine. Would have asked for a flight deck visit if I had! I reckon we should sod the Euro noise regulations and bring back the old metal

[avionic type]

I see the old jokes are begining to come in over the initials B.E.A. etc but it was my airline and I was very happy to work there, I prefered the Trident 1 to the others and was happy to see the Auto pilot from when it started in 1964 as a very basic system to when it reach the system that was trusted to carry out fully automatic Cat3B/C blind landings with complete faith by all. It had 3 of everything 3 separate power supplies ,3 hydralic systems, pitch and roll computers, gyro units, servo units on each control surface so it was a complicated piece of kit
in fact it was 3 auto pilots working together and if 1 disagreed with the other 2 it was automaticlly disconected from the system and the other 2 carried on ,if they disagreed with each other the system disconnected itself and and the A/C reverted to manual flying but after a lot of work it was finally given the authorisation to do what it was designed to do.

[ChristiaanJ]

avionic type,

Myself, I was brought up on the "duplex monitored" principles used on Concorde (and earlier on the VC-10?).

Slightly more hardware, possibly, since each of the two computers contained a complete "duplicate", charged with monitoring the "command" side, and handing over to the other one, if "command" and "monitor" disagreed.

The two computers barely talked to each other (the standby one stayed synchronised, but "kept its mouth shut"), while a triplex system involved a lot more data being exchanged and compared between the computers, hence more and differently designed hardware.

I have no idea what really was the best solution..... espcially since not so soon afterwards we went to digital systems, where we were dealing with a whole new ballpark.

CJ

[WHBM]

Originally Posted by Tom355uk

AFAIK there has never been either a 757 or 767 with more than two engines.... I believe the first two crew civil airliner with more than two engines would have been the MD11, closely followed by the 747-400.

Oh dear, what a cockup. A real victim of too quick cut-and-paste combined with Getawayitis from the office (note a posting time of 1752 on Friday evening !). I suddenly realised the error driving up the M4 Heathrow spur about 30 minutes later. Now I believe the first more than two engined jet with two crew was the BAe146, which does marginally fit the topic as it followed the Trident some years later down the assembly hall at Hatfield. Any parts of the Trident contributed to the 146 ? I believe its main gear design owes a lot to the Comet.

[safetypee]

Any parts of the Trident contributed to the 146 ?

Oh the years I have waited for this trivia question.
IIRC the ‘Q’ pot was the same in both aircraft, and possibly the same design as in the Comet (and even the Sea Vixen).
Greater contributions from the Trident were in the experience gained by the design team, the technical and operational certification, and the practical application of the airworthiness philosophies of triplex systems. These were major advances in modern airworthiness.
Lessons learnt from the Trident – the 146 was strong, well built, also like the 125. The 146 had sparkling field performance in comparison ;-)

The two crew certification of the BAe146 was ‘a first’ in that it had to follow precedence set by the BAC 1-11 and DC 9 types, particularly with the FAA – but they had failed to consider that a two crew, 4 eng aircraft, could exist.

[Adverse Jaw]

After the BEA/BOAC merger, the then L/Haul PLC attempted to preclude the transfer of S/H pilots by imposing an arbitrary experience limit of 4-eng jets only, quite overlooking the fact that Trident 3 was (sometimes) just that and so, a number of the unwashed got their hands on VC10 and B747.

[Aileron Drag]

Yes, AJ, and that was when things got interesting.

We flat-earthers had been taught that the 'OD' crowd were aliens. Their SOPs were odd. Everything about them was odd. The BEA people who migrated to VC10s & 747s were looked upon with awe; as though they were throwing themselves into enemy territory, never to be heard of again.

On the other side of the coin, the rule that new commands must be on short-haul meant we (on the Gripper) were flooded with newly promoted OD 'aliens'.

Guess what - they were great guys, and the barriers came tumbling down.

It's odd now to think how tribal British Airways was, in respect of flight-crew. Forced integration fostered mutual respect. And it started on the Gripper.

Shame the flight-deck / CC barriers still exist. (sorry Mods).

AD

[Midland 331]

Does anyone have anything nice to say about The Trident? The best praise I detect from this fascinating thread is mere polite neutrality. As befits well-mannered Nigels.

I'm guessing that it cruised happily at M0.88 or whatever, and I've read that it could descend impressively when called upon. But were any of the variants a vaguely fun stick and rudder machine? I suspect not the "3"

r

[Aileron Drag]

Midland 331 - no, not the '3'. The Trident 3 was a stretched T2, with 30-odd seats added. Same wings, same undercarriage, same engines. Ergo - it couldn't get off the ground.

So, they stuck a plastic engine in the tail which was either 'off' or 'full-on'. It couldn't be re-lit in the air. In an infamous incident a T3 lost an engine out of Madrid. I recall that this happened after the plastic engine was shut down. The aircraft returned to Madrid, but had to go around on short finals due a blocked runway.

Without the boost engine, the damned thing wouldn't climb engine-out! They flew around at zero feet trying to build up a little kinetic energy!

In short, the T3 was a nightmare. The wings started to crack eventually beacause the weight was too great. Ugh!

Does anyone have anything nice to say about The Trident?

Yes, the T1 & T2 were brilliant. The T1E was even better. I still get wobbly-knees at how fantastic the T1 & 2 were to fly.

It's the dreadful T3 that I'd prefer to forget! Fortunately, I escaped to the 'new' 757 fleet a few months after being press-ganged onto the '3'.

AD

[Hobo]

I had 14 years on the Trident, most of it on the T3. I wouldn't have missed it for anything - great aircraft, great routes and the best bunch of fellow pilots.

From the late 70's onwards, most of the time most people flew manual raw data approaches with manual throttle - just for the pleasure of it, and the level of expertise was second to none.

[slast]

Does anyone have anything nice to say about The Trident?

I think it was the most technically advanced aircraft of its era. It had (IMHO) excellent flying qualities throughout most of the flight envelope but was marred by inadequate performance which was the result of all the b****ing about done by BEA’s management at the very beginning to reduce the basic design requirement. That resulted in it being very difficult to stretch and improve commercially. All the “stretching” done from the 1C to the 3B really just put it back to where it should have been in the first place and exhausted the potential. A T3 with more powerful engines from day 1 could have been stretched to a 200 seater and would have been a real world-beater.

Two examples of its good points. I flew the Trident from early T1 introduction to the point where it started being replaced by the 757 - BA was the launch customer for the 757 along with Eastern. I was lucky enough to be involved on the BA/BALPA 757 liaison team, so we saw a lot of the development work from the inside and got to know a lot of the Boeing test pilots and engineers.

When I managed to get qualified on the 757 fairly soon after it was introduced, there was a conversation with some of the Boeing guys (maybe together with Peter Harper who was the BALPA Tech Committee chairman at the time and also qualified on it) along the lines of “how do you like your new ship?” To which the reply was while we LOVED the power and performance, we weren’t very impressed by the flying qualities which seemed like a step backwards. A Trident handled like a sports car in terms of control response especially in roll, it also had very little trim change with speed and configuration and very light control forces. With a 757 if you took the wheel and rotated it quickly it from one side to the other and back to neutral, the aircraft would just sort of “turn round and look at you” as if to say “oh, are you talking to me?”. Similarly, with an asymmetric approach, every time you changed the power, you had to re-trim in all three axes.

Maybe these comments were slightly exaggerated for effect, but the Boeing guys were astonished and said that we ex-Trident pilots were the only people who had commented negatively about the 757’s flying qualities. But the only other people who had been exposed to it at that time were accustomed to other Boeing and/or Douglas products and measuring from a different "norm".

Another early experience was when I flew a 757 service which replaced the Trident on either Brussels or Amsterdam, and we had thick fog. I had to delay departure for quite a while till the RVR improved as the lowest 757 takeoff RVR was higher than that of the Trident with its PVDs. It was caustically noted by some of our regular passengers the old T1s that were then being broken up had a better all-weather capability than their shiny new replacements!

[Prober]

…anything nice to say about…

Yes, they do. We ex Gripper chaps are professional aviators and we do not go all gooey over our aircraft. We flew and enjoyed ourselves without fuss. (Tongue in cheek, in case.) I went from “Guardsvan” to Tridents as F/O, back to Merchantman as LHS and then back to Tridents. I had 2 years in each of the Trident seats and enjoyed it immensely. It really was a marvelous aeroplane and going back to the VC9 seemed like going back to the stone age. I remember Slast very well but did not have nearly such a distinguished Trident career as he did, so I cannot comment on the background of much that went on. I remember well sitting on the edge of my seat during the early days of autoland. There was an alarming, but fortunately rare, likelihood that it would either try a reverse acquire or do something equaling entertaining at the flare. I used to wish that all the dolls eyes and other A/L indications could be grouped together in a ladder, to advance progressively to (hopefully) give a LAND decision. I, too, converted to the 75 and there was the ASA!! And I was dumbstruck at climbing to FL410 in 20 mins – on the Gripper, one applied “contingency power” (an extra 200 rpm!) when the rate of climb fell to 300fpm. Getting to cruise could easily take 30 mins or more and yes, the T2 had a Fin tank which would be empty before TOC. But to answer the question – YES, it was brilliant and great fun to fly. Only the 767 has anything like its controls response – and that definitely in ROLL only.
I remember the report on the 2 eng go around for the T3 at MAD (the R/W layout had been sitting there just waiting for this to happen). The average ROC was 200 FPM and the ATC reported that when it disappeared behind the hills they did not expect to see it reappear. I never discovered why the Boost was never cleared for an inflight start – I bet that crew wished it had!
Prober

[Hobo]

Subsequent to the MAD incident, a procedure was introduced where the boost could be started in flight. It involved a very lengthy procedure with CB's being pulled to make it think it was on the ground and an extremely small relight speed window (IIRC). The Chinese insisted on this from the start on their T3's.

With Gil Gray, I took one of the T3's to Hatfield for sorting out the wing cracks. While we were waiting for the transport back to LHR John Cunningham showed us round one of the Chinese examples. All the decals were in Chinese and the flight deck extended back to the fwd door, where the fwd toilet usually was, to make space for a huge desk portside rear, where the 'Commondant' of the aircraft sat - inter alia making sure the crew didn't defect to the West.

[Adverse Jaw]

I too spent 9 happy years on the Trident mainly Threes and don't recognise some of the adverse comments made. As conveyed so well by Steve, the problems of lack of thrust were of BEA's making - but entering a descent after boost engine shutdown - absolute tosh. As for its flying qualities they were superb - and I've seen it up to the high subsonics, with no signs of mach buffet or need for artificial devices. By contrast, the Tristar required the terrifying Recovery Speed Brake and the DC10 hit a wall above M.85 needing bank angle limitation to obviate buffet during cruise.
How good to see Pete and Steve going strong though Pete barely recognisable without pipe.

[slast]

poor performance

I think one of the reasons that the "it wouldn't climb with an engine out" story came so common was actually that the aircraft obviously DID meet the requirement to be able to climb - but without much to spare most of the time! Most people (fortunately!) don't ever experience how low a gradient and how little clearance is actually required to meet the performance requirements - it is very little indeed!

Virtually all our experience is gained with all engines operating, and in circumstances where we are well within the limits of the performance envelope. In normal operation the Gripper unfortunately seemed to sit a lot closer to the edges of the envelope than most other types do. Fortunately at that time the ARB (predecessors to the CAA) used to require a sample of every fleet to be air tested each year to ensure that the overall performance was still typical of that demonstrated in initial certification. I suspect (I don't know) that's been jettisoned under JAA/FAA harmonisation of rules as the Americans certainly didn't like that idea, but I remember flying as P3 to Gordon Corps doing one of these recurrent air tests. (Gordon was CAA chief test pilot before joining Airbus in 1982, and a member of the SAE S-7 "what goes where" committee I referred to earlier (Post #117). One certainly realised how little climb capability was needed to meet the rules when seeing it demonstrated by someone like that - I was stunned by how precisely he could fly the aircraft straight off the ground when probably he hadn't been near one for over a year, and any "wobbles" away from the precise optimum speed would certainly affect the outcome.