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B737NG A/P, what a joke!

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B737NG A/P, what a joke!

Old 1st Sep 2002, 22:02
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B737NG A/P, what a joke!

I´ve flown several types including aircraft from BAe, Fokker, MD and now I´m on the B737NG. Honestly, I was very disappointed with the level of performance of the autopilots. I find them very rough and the FMC is definitely not as good as the ones on the MD-11 or the F-100. To be honest, I was not at all impressed with the aircraft itself. I understand the airplane had to be designed that way to reduce costs, but they could have definitely made an improvement to the A/P and especially to the FMC. They should have learned a few things from Mr. Douglas. Opinions please.
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Old 1st Sep 2002, 22:17
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just out of curiosity, which phases of flight do you find the autopilot rough? Also do you find the rudder movement sluggish?
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Old 1st Sep 2002, 22:23
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I will give you an example. If the you command an acceleration during climb, the autopilot accelerates to that speed and instead of smoothly pitching up to climb, it agressively pitches up. On the otherhand, during descent, if ATC tells you to reduce speed, the autopilot is not assertive enough during a level change descent. It will maintain a certain V/S and the airspeed itself will decrease very slowly requiring either a speedbrake or V/S intervention from the pilot.
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Old 2nd Sep 2002, 12:18
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Mork,

Although I don't have any other experience on other types than 737, I do agree with you. I often get the feeling that the AP system, wich is completely similar to the -300/400 AP, can't cope with the higher speeds and altitudes of the NG. The VNAV mode has terrible speed and path control, both in climb and descent. And what do you think about LOC capture compared to other types?
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Old 3rd Sep 2002, 12:58
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Wink

I have no experience of the 737, but I can`t beleive any A/P is worse than the one on the 146!!! On selecting Flap 18, a rise of 100ft is the norm, but I have seen over 300ft!! Add to that consistently cruising at 100ft abve the selected altitude at higher levels and speeds! Keeps us awake though!!!
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Old 5th Sep 2002, 23:04
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If you're going to criticise the NG, don't stop at the AP system. This aircraft should never have been built.

The real B737 update for the 1980s/90s/2000+ was designed a little before the NG. It's called the A320 family.

A 'modern' aircraft with toggle switches, Cat 3A only, AN INCREDIBLY NOISY FLIGHT DECK, dodgy fuel pumps, a max speed of 270kts if it's been de-iced, a wing which creates ice wherever/whenever you fly it, only two IRS and one FMC etc etc, has no place is civil aviation. The whole thing is a joke, and a bad one at that. The comedians were those who insisted upon the economic benefits of a common type rating at the expense of progress and safety.

Just my opinion
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Old 7th Sep 2002, 06:31
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Question

Is the one FMC an airline option? I flew the 757 as FO a few years ago. We had two panels for this. The Canadian CRJ often has only one (and at ASA, no autothrottles). So far, the 757 is my only Boeing experience. It still has a very slow microprocessor, which the airline could have upgraded-but that would cost money. Only after we made all the alt restrictions with VNAV, we then used FLCH when descending below 10,000', and it often seemed sluggish. But it will keep the present airspeed and smoothly climb or descend, won't it? VS was a bit risky. We never used it in a climb, except for a gradual level-off when hand-flying up to 12,000' or so (i.e., 1500 fpm at the "two to go" callout-less power and pitch required while chasing the flight director, much more gentle on the sullen, ragged prisoners in the cabin (yes, most dress in their worst clothes, as if they are ashamed to be on an airplane...MTV-conditioned?), in order to avoid pushing forward to quickly on the yoke (as with VNAV, which uses full climb power), to avoid overshooting an altitude. If there is a real delay in what it is doing (anytime in newer tech cockpits), click the autopilot off, re-engage it and both Flt Dir switches and push the FLCH etc button again.

By the way, our new 757-300s will only use the climb thrust which is on the -200. Are different FADECS required at a huge price increase, or is it much less engine wear to not have the higher climb thrust?

So how do the 757 autopilot and "magic' compare to those on the 737 NG? One thing is for sure-these require no flight computers and the throttles on Boeings always move-as with every plane most people have ever flown.

Anyway, I'm back on old technology and am stinkier and sweatier while guarding the throttles as more runway under us, but most of all, feel like an airplane pilot again. Do Airbus pilots feel like pilots?
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Old 7th Sep 2002, 22:32
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Mork,

During preflight, programme your Vnav Climb, ruise and Descent pages as follows. Climb 300/.78; Crusie .79; Descent 300/.79. This will solve the noise problem. Over 300 kts the noise level seems to go up exponentially. Also the autopilot seems to love these airspeeds. VNAV mode does pretty well at these speeds.

When you're getting vectored dogleg to final, Cheat to the Magenta line when "cleared for the approach". If you're given a 30 deggree dogleg and told to intercept the ILS final. Cheat over to a 15 degree intercept before the VOR/LOC capture. The autopilot capture phase is much smoother. This is an old 767 technique.

737 pitch and power figures is "money in the bank'. They work! You don't need the FD. 60% N1 gets you started for most traffic pattern manuevering. 1,3,5,10,15 degrees of pitch work for the climb cruise, descent and GA phase. I'll let you figure out which is which. The intrument crosscheck is still a "T" check despite all the glass.

I used the love the 757/767. Now I'm wild about the 737NG. Give it a bit of time and you'll love it too. The autopilot is a bit on the lame side, like dropping off during the GA or hard turns at altitude, but there's lots of easy ways to cope the things you don't like about it. I've flown AIRBUS', Boeing are much better. How would you like to have an autopilot that you couldn't override with force disconnect switches! That's Airbus, incredible. The best part of flying a Boeing is that you truly feel like a pilot.

d
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Old 8th Sep 2002, 17:21
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Another thing about the NG autopilot, I've seen it once (and a mate of mine twice) bank over 30 degrees of bank on in LNAV, when it's blown out of a turn calculated for a slower speed than it's actually doing. Now the A/P overshooting the turn is my fault perhaps, but any A/P should NEVER overbank to that extent (on 2 of 3 occasions it triggered the GPWS bank angle warning before it could be taken out of LNAV). That's just bad design.
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Old 8th Sep 2002, 21:58
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The MCP looks very similar to the 744's. An ergonomic cock-up. I'm sure design of the thing commenced at 3.00pm on a friday afternoon just before the pubs opened!
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Old 8th Sep 2002, 23:29
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. How would you like to have an autopilot that you couldn't override with force disconnect switches! That's Airbus, incredible

Must be an A300/310 then. I'm forever knocking the sidestick and disconnecting the AP on the A319. Certainly wakes me up!
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Old 9th Sep 2002, 18:14
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DVT,

This thread discusses the design limitations of the NG compared to other aircraft of the same design era (late 80's and 90's).

Personally I feel that if you have to "cheat" the AP (and ATC) for a smooth intercept the design is lacking. Secondly, handflying circuits, approaches and level-offs sounds an afwul lot like the good old -200. Very nice machine indeed, 30 years ago... I'm definetely a Boeing fan but they could have done much better on this one.

And the noise ............
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Old 11th Sep 2002, 04:19
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My appologies...

I wasn't aware thread was limited to those who only want to throw tomatoes at an airplane that has an incredible safety record and is a proven money maker for its operators.

Personally, I want no part of a design philosophy that helps makes my hard earned pilot skills rusty or irrelevant. If you're going to fly this airplane well, you better dust off all your pilot skills because you'll need them in just about every phase of flight. No doubt about it. But, there's nothing like the confidence of knowing you're flying this plane and not the other way around.

The autopilot is not a joke. It's an aid/tool to be used when appropriate. I think of my autopilot as an apprentice with limited flying skills. When my autopilot is not performing up to snuff, I relish the oppurtunity to say...click, click...I have the airplane.

d
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Old 11th Sep 2002, 07:53
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dont trash the bus

hi Northern Sky
i am great fan of Mr Boeing,infact the 737-200 is still my favourite piece of flying hardware(no fear of anything remotely resembling software here,if you dont count the PDCS or the hand held GPS!)
But i am also an A320 driver.My airline owns 30 of these machines and has a further 8 on dry lease.They all have 3 IRS's and 2 FMGC's as standard equipment.i have not had occassion to compare the 737 NGs A/P with the 320s,but we are quite happy with ours Thankyou.Perhaps in future you will endeavour to get your facts right,before jumping into the fray!
Happy Landings
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Old 14th Sep 2002, 15:01
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Phoenix X - From the 737 300 manual 'If winds are greater than expected when actually flying the turn, LNAV can command up to 35 degree of bank.

I presume the NG is the same or similar.

I do find the classic A/P flies the plane badly, especially in climbs and descents, and on single channel approaches. However, it is extremely well designed in terms of the pilot interface. It is very intuitive and you never find it doing something unexpected - 'what's it doing now' is very rarely heard on a 737 flight deck.

The FMS (U7.5 onwards) is superb, and far superior to the Airbus (no fix page etc).
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Old 16th Sep 2002, 23:51
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nightbird,

My facts are straight. You have mis-interpreted my post, I fear. My criticism was levelled at the Boeing - the Airbus is the superior product by a long, long, way. The Boeing is the one with only one FMC, an incredibly dodgy AFCS, an alerting system out of the ark, cheap-and-nasty flaps and slats, etc etc.

Please, read more carefully. Or at least more carefully than you write. I is 'I' not 'i', spaces follow full stops, and plurals don't take apostrophes. (No offense intended).
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Old 17th Sep 2002, 11:03
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Got two FMC's in ours - probably an option which seems to me to make sense for those operators not wanting to spend an extra half million or something........ what's all the fuss anyhow? I think it's a great aeroplane. Someone needs to find something more in their life if all they can do is sit around criticising other kids toys!
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Old 17th Sep 2002, 18:21
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Hi NorthernSky,
Thanks for clearing that up.
i guess Dick Bach need'nt worry about being put out of business by either one of us!
Hope Boeing starts work on a truly GN(Generation Next) 737 soon
Regards
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Old 25th Sep 2002, 05:20
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Don't thank Boeing, thank your employers (the airlines). When the NG was being developed they wanted it to be like the "classics", not some "new" '90's airplane with all of the latest gadgets. It is nice to know that if you have a total electrical/hydraulic failure that you can still fly the 737.

Same goes for the dual FMC's. Up to the airlines.

Don't knock the plane, it must be pretty good to still be in service and in demand after all of these years.
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Old 8th Oct 2002, 11:39
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On the subject of the NG's A/P performance, I have only one complaint myself; and that is that at its enroute's VNAV's 300+ knots it will pull up on a 30 degree bank in LNAV when turning when more than 45 degrees off course. That imposes some "G" forces on my pax and myself that are, say, unconfortable. Then, is the time when you take it out of LNAV, set it to HDG SEL and 20 degrees bank and anticipate the turn that way. Other than that, I have no problem with the A/P performance. As someone said earlier in a thread, the A/P is there to help you, not to FLY for you. There are many instances in which reality catches up with A/P design limitations and that is the time you have to take over control and fly it manually! Be it windshear, ATC vectoring or greater tailwinds than expected. Yes, boys and girls, believe it or not, to fly manually is still a required skill for an airline pilot! Don't bash the NG senselessly as there is no point in doing so, as its commercial success speaks for itself. Boeing engineers did want it to be so much more up to date, technologically speaking, but it was the customers who mandated it to be the way it turned out to be. Personally I enjoy flying it manually a lot; as Jim Webb said once, just 'Fly the Wing',
and when you fly this aircraft, that is what you do, you fly this magnificent new wing Boeing put on the B-737. As to the Airbus vs. Boeing never ending feud, let me just say that with Boeing, the pilot is still the final decision maker as to when what and how much, that is not the case in Airbus and just for that reason alone, Boeing will always be more dear to me than Airbus ever will, no matter how sophisticated its avionics and systems are.

Last edited by Finalveridict; 8th Oct 2002 at 11:44.
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