Trident autothrust system and autoland
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Lederhosen
What a great fim! I love the bit with the test pilot nonchalantly talking to the camera over his shoulder as the aircraft descends through two hundred feet. Talk about confidence in the autoland system.
Forty years later I am not sure how much things have improved. I certainly would not feel comfortable doing that on my 737....not after the autopilots tripped out in the flare a few weeks ago! Certainly got my attention.
Forty years later I am not sure how much things have improved. I certainly would not feel comfortable doing that on my 737....not after the autopilots tripped out in the flare a few weeks ago! Certainly got my attention.
I remember a 1983 Autoland approach to (I think) 10R at LHR in a BA 737 ex Moscow. We could see aircraft on approach disappearing into the clag from about overhead Beaconsfield VOR and all innocent, I asked if we would doing an autoland?The reply was that they wouldn't, ordinarily, do one because they would probably break out at 1000ft and land mandraulically, but since I'd asked and they hadn't done one in a few weeks ......
It was fascinating and just like the first film clip. The FO sat with his hands on his knees, watching and the Captain was turned round chatting to me! Mind you, just before touch down they both said "Ohhh no!" and there was a hell of a bang on landing. Stuff fell out of the rack behind me and I was clearing it off the centre console as we braked.
Obviously I asked ......Apparently the Trident and BAC111 had their A/L set up to do 'greasers' on the long runways of Europe, but Boeing set up theirs to trip the WOW switches "on the zebra stripes". Obviously so the 737 can land in foul weather at indifferent airfields in Battle Creek, Michigan without falling off the runway.
A very interesting evening that. 
And if you are still reading; thanks to those two and all the other crews who put up with me in dozens of cockpits around the world. 
Roger.
We have to do one a month for currency plus the real ones so over the years I have probably done a couple of hundred on the 737. Actually I don't think it does a bad job, not noticeably worse than us anyway. 
I do not believe it is set up to make a dirty dive for the beginning of the runway, however good a story that might be. It follows the glideslope which as a cursory scan of the Jepp chart shows can lead to a quite different point. It also doesn't call you a retard in the flare, a pleasure I am soon to enjoy.
However if you do a practice autoland for currency purposes unprotected (e.g. low vis procedures not in force) there seems to be a marked tendency on our early NGs for the autopilots to trip out when the previous aircraft clears the runway.
I am fascinated by Prober's story of trying to autoland off a non precision approach. The concept of the aircraft flying based on memory seems to have been resurrected in part on our newer aircraft which are more tolerant of minor beam deviations. So again there is not much new under the sun. However the rest of it (and the earlier VSP anecdote) reinforces why some pilots get into management and maybe should stay there.
I do not believe it is set up to make a dirty dive for the beginning of the runway, however good a story that might be. It follows the glideslope which as a cursory scan of the Jepp chart shows can lead to a quite different point. It also doesn't call you a retard in the flare, a pleasure I am soon to enjoy.
However if you do a practice autoland for currency purposes unprotected (e.g. low vis procedures not in force) there seems to be a marked tendency on our early NGs for the autopilots to trip out when the previous aircraft clears the runway.
I am fascinated by Prober's story of trying to autoland off a non precision approach. The concept of the aircraft flying based on memory seems to have been resurrected in part on our newer aircraft which are more tolerant of minor beam deviations. So again there is not much new under the sun. However the rest of it (and the earlier VSP anecdote) reinforces why some pilots get into management and maybe should stay there.
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but Boeing set up theirs to trip the WOW switches "on the zebra stripes". Obviously so the 737 can land in foul weather at indifferent airfields in Battle Creek, Michigan without falling off the runway.
I remember one of my instructors talking about auto-land. He said: "The autopilot doesn't care for a greaser. Its job is to put the airplane in the TDZ, sometimes it pulls a greaser but when the conditions are appropriate it comes out quite a smack-down"
The film was ALL IN A DAYS FLYING - 1965 director Richard Dimbleby and narrated Johnny Morris who did Animal magic.
It showed a VC10 trip with captain Bill Williams and his son who was at Hamble at the time as well as a Trident one with a GVA and Nice turnaround with shopping excursions. ( Nice was rather impoverished at the time)
The Trident 1 carried out a typical controlled crash - no real attempt to kick off the drift or flare.
We all winced when we were shown it during current affairs at Hamble - thought that the landing should have been left on the cutting room floor!
It was shown as a B movie and for recruiting for the corporations.
Still available for around a tenner from Phil Nelson - link via the Hamble website.
A very good example of the privileged life of a pilot in both of the corporations at the time.
I was one of a handful of guys who experienced both the gripper and the Iron duck.
It showed a VC10 trip with captain Bill Williams and his son who was at Hamble at the time as well as a Trident one with a GVA and Nice turnaround with shopping excursions. ( Nice was rather impoverished at the time)
The Trident 1 carried out a typical controlled crash - no real attempt to kick off the drift or flare.
We all winced when we were shown it during current affairs at Hamble - thought that the landing should have been left on the cutting room floor!
It was shown as a B movie and for recruiting for the corporations.
Still available for around a tenner from Phil Nelson - link via the Hamble website.
A very good example of the privileged life of a pilot in both of the corporations at the time.
I was one of a handful of guys who experienced both the gripper and the Iron duck.
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Speaking of the Trident wing versus the 727 -take a look at this cracking shot. The way that wing 'came apart' always impressed me.
http://www.pprune.org/spectators-bal...fahd-b727.html
http://www.pprune.org/spectators-bal...fahd-b727.html
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Have enjoyed reading this thread. Flew a lot on Tridents (as SLF) from the mid 70's and loved the aircraft from a pax point of view although some interesting moments.
Any support for a Trident thread on AH & N for some more of those stories?
Any support for a Trident thread on AH & N for some more of those stories?
Prober - was it Capt. Ormonroyd who was the intrepid aviator that removed the Comets fin in a low go-around at Bedford?
ASN Aircraft accident de Havilland DH-106 Comet 3B XP915 Bedford-Thurleigh Airport
It was in the days of training accidents seemed to be part of normal life in the BEA group (several tridents, the odd Vanguard and Airtours 707).
ASN Aircraft accident de Havilland DH-106 Comet 3B XP915 Bedford-Thurleigh Airport
It was in the days of training accidents seemed to be part of normal life in the BEA group (several tridents, the odd Vanguard and Airtours 707).
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Thanks for that Pew - hadn't heard of that one although my father told many tales of many others. He'd spend weeks on T1's and T2's at Shannon and Prestwick doing base training at a time when fuel was cheap and I presume simulators poor. He certainly got rather tired of being required to use autoland as often as possible to build up the reference database. He claimed that the passengers didn't like it as it was prone to give a rather more agricultural arrival than the manual version. I presume today it'd all be done on the simulator.
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Shannon base training
The 1st Trident sims were very sophisticated - by the standards of the day!!
I was on one of the first Hamster courses so if cremeegg's dad was a trainer he may have done me.... be interesting to know but would kind of bust your anonymity. Anyway at that time (winter 65-66? again I'll have to find the logbook) the sim. was not approved for stall training, so we did full aerodynamic stalls in the aircraft at Shannon. Must have been exciting for those skippers, with a kid with all of 250 hours in each of the other 2 operating seats, and a T-tail aircraft with a known deep stall potential! The supervisory F/Os assigned to "mentor" us had their work cut out and were outstanding guys as well.
One story about the Shannon Base Training.
We were on day 1, Geoff Fowkes (lovely gent) was the boss. We must have spent 45 mins doing the preflight setup (remember we had no "part function simulators" or "procedures mockups"), while the Shannon ground mech is hanging around underneath on the headset in the winter breeze. Eventually Geoff says "Hello Ground, we're ready to start".
"Sorry skipper, it'll be just a moment now, we've got a shift change". Click of intercom, we watch him walk off to the hut. We twiddle our thumbs for 10 minutes and there's another click on the intercom. "OK skipper you're clear to start now".
Geoff: "are you the gentleman who was here before?"
Ground "that's roight"
Geoff "I thought you were having a shift change?"
Ground "That's roight, oi'm on a double shift today! Do you want to start up?"
So we start, taxy off and fly circuits for several hours before returning to the pleasures of the Limerick Intercontinental Hotel, our first experience of the lavish lifestyle we were to become accustomed to as "BEA pilots on the fastest jet airliner in the world" (well it was at the time !!)......
I was on one of the first Hamster courses so if cremeegg's dad was a trainer he may have done me.... be interesting to know but would kind of bust your anonymity. Anyway at that time (winter 65-66? again I'll have to find the logbook) the sim. was not approved for stall training, so we did full aerodynamic stalls in the aircraft at Shannon. Must have been exciting for those skippers, with a kid with all of 250 hours in each of the other 2 operating seats, and a T-tail aircraft with a known deep stall potential! The supervisory F/Os assigned to "mentor" us had their work cut out and were outstanding guys as well.
One story about the Shannon Base Training.
We were on day 1, Geoff Fowkes (lovely gent) was the boss. We must have spent 45 mins doing the preflight setup (remember we had no "part function simulators" or "procedures mockups"), while the Shannon ground mech is hanging around underneath on the headset in the winter breeze. Eventually Geoff says "Hello Ground, we're ready to start".
"Sorry skipper, it'll be just a moment now, we've got a shift change". Click of intercom, we watch him walk off to the hut. We twiddle our thumbs for 10 minutes and there's another click on the intercom. "OK skipper you're clear to start now".
Geoff: "are you the gentleman who was here before?"
Ground "that's roight"
Geoff "I thought you were having a shift change?"
Ground "That's roight, oi'm on a double shift today! Do you want to start up?"
So we start, taxy off and fly circuits for several hours before returning to the pleasures of the Limerick Intercontinental Hotel, our first experience of the lavish lifestyle we were to become accustomed to as "BEA pilots on the fastest jet airliner in the world" (well it was at the time !!)......
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As not much response to my suggestion that a new thread on AH&N might elicit more fascinating insight into this aircraft maybe a new technical question - Mods feel free to move/delete or suggest a completely new thread if you feel too much thread creep here!!
From my few visits to the 'Best Seats In The House' end of the Trident I recall that it apparently had a moving map display which seemed to consist of a paper (?) scroll and a moving pen? I cant imagine how this worked let alone how you guys used it on longer sectors.
From my few visits to the 'Best Seats In The House' end of the Trident I recall that it apparently had a moving map display which seemed to consist of a paper (?) scroll and a moving pen? I cant imagine how this worked let alone how you guys used it on longer sectors.
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Wookey,
It seems most of the Trident crowd has congregated here, so why not stay here?
"....a moving map display which seemed to consist of a paper (?) scroll and a moving pen?"
Ah, you're opening a new can of worms as well!
No, the scroll was some type of Mylar, and the moving pen was a moving marker.
But I'm as curious as you to hear a bit more about its workings!
By the time Concorde came around, they'd progressed to a projected moving map display, using projected maps stored on film.
And in the case of Concorde it was thrown out almost as soon as it arrived... a bit useless over water, and replaced by the INS.
Only the prototypes had it, and even then only in the earlier days.
CJ
It seems most of the Trident crowd has congregated here, so why not stay here?
"....a moving map display which seemed to consist of a paper (?) scroll and a moving pen?"
Ah, you're opening a new can of worms as well!
No, the scroll was some type of Mylar, and the moving pen was a moving marker.
But I'm as curious as you to hear a bit more about its workings!
By the time Concorde came around, they'd progressed to a projected moving map display, using projected maps stored on film.
And in the case of Concorde it was thrown out almost as soon as it arrived... a bit useless over water, and replaced by the INS.
Only the prototypes had it, and even then only in the earlier days.
CJ
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The moving map was worked by "Doppler" and that also showed on the Doppler Ground Speed and drift instrument above it. The First Officer put the Doppler map position right occasionally when passing a fix. Then it did its own thing by applying its own calculated speed and drift. It did not, in my experience, do this very well and I always said that Doppler was only right when the First Officer had put it right!
I thought the Trident had Decca Harco navigation with moving map display.
I seem to recall that it was fitted to the BAC 1-11s of BEA also.
I saw a few of these at Hurn in the early '70s.
I also worked on a Jetstream and a Hughes 500 with Decca Danac which was similar to the Harco.
I seem to recall that it was fitted to the BAC 1-11s of BEA also.
I saw a few of these at Hurn in the early '70s.
I also worked on a Jetstream and a Hughes 500 with Decca Danac which was similar to the Harco.
Doppler and the Trident's Voice Activated Autopilot
The Doppler navigation used a x-shaped antenna in the belly - it rotated so that when each side was reading an equal groundspeed the angle relative to centreline = drift.
There’s more info on a couple of other pprune pages and a good photo at Photos: Hawker Siddeley HS-121 Trident 3B Aircraft Pictures | Airliners.net
The Special Reactive Instant Navigation Geographic Current Location Indicator Pointer” (SPRINGCLIP) fixed just above the map in the pictures is holding a bare metal rod I think, initially there was a pen with a little ink reservoir on it. The idea was to have a permanent “flight recorder readout” of actual track flown for record purposes e.g. to improve airspace usage etc., most F/Os were glad that got dropped pretty early as there was often more ink on fingers than map! Also the maps had to be route specific so started to be significant cost as single use items.
Drift could be fed to the autoflight system, in fact IIRC the steering was actually looking to keep commanded track not heading per se. Just below the compass you can see a horizontal rectangle with 4 white marks on it (can’t remember what they are). This covered a drift selector, with it open you set drift yourself (e.g. to fly radar heading set it to zero) and with it closed as in the picture drift was auto. (I think!!)
The current “actual drift and G/S” are just above the map in the picture. As PeteMcleland has just pointed out this could be adjusted because Doppler wasn’t always reliable especially above e.g. smooth water or snow. The adjustment was by an X shaped switch at the rear of the centre pedestal. Move the switch > change the drift and groundspeed readouts. As Peter says the actual display motors could also be adjusted to drive the pointer around the map.
Voice activated autopilot. This was a very advanced feature only occasionally demonstrated to a certain category of SLF. It was only available after the introduction of the Cockpit Voice Recorder and required good outside visibility. The mike for the CVR was located in the overhead towards the back of the centre panel. Remember the Gripper had 3 pilots. Remember F/Os flew alternate legs as RHS pilot and “Flight Engineer” (all qualified in both seats). Also we operated with noise muffler headsets and used intercom as standard.
Suitable SLF asks usual questions – gosh isn’t it small in here, do you understand all those knobs and dials, what do you do all the time ‘cos it’s all automatic now isn’t it?” 2 front pilots deal with SLF questions, P3(F/E) apparently oblivious of visitor.
Response to question 3 “yes it’s so automatic we don’t even have to turn any knobs any more, it’s voice activated”
“NO!?!”
“want a demo? OK lean forward a bit and speak into that mike.” (You see where the SLF needed appropriate qualifications now) “ Say clearly “TURN LEFT”.
SLF: “TURN LEFT!”
P3's left hand resting nonchalantly on rear of centre console increases right drift ……. Autopilot senses drift error, banks aircraft left …………
You get the drift I’m sure….
Steve
There’s more info on a couple of other pprune pages and a good photo at Photos: Hawker Siddeley HS-121 Trident 3B Aircraft Pictures | Airliners.net
The Special Reactive Instant Navigation Geographic Current Location Indicator Pointer” (SPRINGCLIP) fixed just above the map in the pictures is holding a bare metal rod I think, initially there was a pen with a little ink reservoir on it. The idea was to have a permanent “flight recorder readout” of actual track flown for record purposes e.g. to improve airspace usage etc., most F/Os were glad that got dropped pretty early as there was often more ink on fingers than map! Also the maps had to be route specific so started to be significant cost as single use items.
Drift could be fed to the autoflight system, in fact IIRC the steering was actually looking to keep commanded track not heading per se. Just below the compass you can see a horizontal rectangle with 4 white marks on it (can’t remember what they are). This covered a drift selector, with it open you set drift yourself (e.g. to fly radar heading set it to zero) and with it closed as in the picture drift was auto. (I think!!)
The current “actual drift and G/S” are just above the map in the picture. As PeteMcleland has just pointed out this could be adjusted because Doppler wasn’t always reliable especially above e.g. smooth water or snow. The adjustment was by an X shaped switch at the rear of the centre pedestal. Move the switch > change the drift and groundspeed readouts. As Peter says the actual display motors could also be adjusted to drive the pointer around the map.
Voice activated autopilot. This was a very advanced feature only occasionally demonstrated to a certain category of SLF. It was only available after the introduction of the Cockpit Voice Recorder and required good outside visibility. The mike for the CVR was located in the overhead towards the back of the centre panel. Remember the Gripper had 3 pilots. Remember F/Os flew alternate legs as RHS pilot and “Flight Engineer” (all qualified in both seats). Also we operated with noise muffler headsets and used intercom as standard.
Suitable SLF asks usual questions – gosh isn’t it small in here, do you understand all those knobs and dials, what do you do all the time ‘cos it’s all automatic now isn’t it?” 2 front pilots deal with SLF questions, P3(F/E) apparently oblivious of visitor.
Response to question 3 “yes it’s so automatic we don’t even have to turn any knobs any more, it’s voice activated”
“NO!?!”
“want a demo? OK lean forward a bit and speak into that mike.” (You see where the SLF needed appropriate qualifications now) “ Say clearly “TURN LEFT”.
SLF: “TURN LEFT!”
P3's left hand resting nonchalantly on rear of centre console increases right drift ……. Autopilot senses drift error, banks aircraft left …………
You get the drift I’m sure….
Steve
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slast,
Steve... ROFLMAO re the VOAP....
Thanks for the other info too.... so I was wrong, and it was indeed paper at the time. (Love the perforations...)
dixi188,
The Doppler of course was "dead-reckoning" and "self-contained" if indeed less accurate than INS or nowadays GPS.
Decca would provide a "true position", but IIRC, by that time Decca coverage (being ground-based) was totally inadequate for the typical BEA route structure.
Looking forward to more info.
CJ
Steve... ROFLMAO re the VOAP....
Thanks for the other info too.... so I was wrong, and it was indeed paper at the time. (Love the perforations...)
dixi188,
The Doppler of course was "dead-reckoning" and "self-contained" if indeed less accurate than INS or nowadays GPS.
Decca would provide a "true position", but IIRC, by that time Decca coverage (being ground-based) was totally inadequate for the typical BEA route structure.
Looking forward to more info.
CJ
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Steve,
Above the box where you type your words into your post there is a small yellow cartoon quote. Highlight any of you own text or any you have copied and pasted, and click on this.
Flew all the Tridents for 14 years (once or twice with you)....happy days.
where on PPRuNe does it tell you how to insert quotes in messages?)
Steve
Steve
Flew all the Tridents for 14 years (once or twice with you)....happy days.