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Driver170

Steep des to glide slope

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Landing rwy 06 EGPH STAR TWEED2A trans TLA

 

I arrived at 4000 MSL as stated in the approach chart and the nav data coded into the FMC and showing in the legs page! Just before the FAF (Loc already captured) my setup is fail passive. Pressed loc first then app and soon as i captured the G/S it pitched down quite alot and my IAS reached 200 kts but soon established and fixed itself.

 

Why is this doing this my last flight was smooth?

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Why is this doing this my last flight was smooth?

 

Was the last flight that was smooth into the same airport using the same approach?

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No it was different! I wont mention my des path unachievable when descending had to go into a hold. Just seems a tricky job des the 737 800 without getting messages do i have to start using spd int or lvl change and speed up to get back on the des path?

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Pressed loc first then app and soon as i captured the G/S it pitched down quite alot

 

You don't have to hit LOC first.  If you pressed APP late, then I'm not at all surprised that the aircraft would pitch down a good bit to catch up with the GS.  If you see both LOC and GS diamonds, just hit APP...

 

 

 


Just seems a tricky job des the 737 800 without getting messages do i have to start using spd int or lvl change and speed up to get back on the des path?

 

Yes.  There's a pilot up front for a reason.  He or she must use his or her brain to assess the changing situation, and adapt accordingly.  Some STARs aren't very nicely designed when it comes to certain aircraft.  As the 800W is very slippery, some profile descents are tough to execute and require pilot intervention.  Additionally, if you're not using the DES FORECAST function, you should be:

 

 

...and once you understand that part:

 

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No it was different! I wont mention my des path unachievable when descending had to go into a hold. Just seems a tricky job des the 737 800 without getting messages do i have to start using spd int or lvl change and speed up to get back on the des path?

Vernon

 

Des path unachievable while not a normal message in nothing to really be alarmed about. I receive that message from time to time whether I am in VNAV or V/S modes. If you are in VNAV mode go to V/S, increase the rate of descent, extend speedbrakes, and dial in a lower speed.

 

I don't know where the hold was but if was during the STAR it is unusual but it happens. There are several STARS I encounter with altitude and speed constraints that I need to do a hold to lose speed and altitude maybe 10-15% of time. It seems as if the STARS were laid out just to torment pilots. I know they weren't but that's the way it seems.

 

Forget level change at this low of an altitude. I never use speed intervention so I can comment on it.

 

Make sure your flaps are set so FMC commanded speeds can be achieved.

 

If you have not looked at these videos in this thread you might want to http://forum.avsim.net/topic/443403-new-video-tutorial-series-how-to-fly-a-perfect-ils/. I believe you mentioned these in another thread. There are out now for you to look at.

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We (my airline) have this awesome tool from Boeing that gives us descent winds and ISA DEV. For some reason, it won't grab the BARO setting. Dunno. Anyway, it's designed to help us get a better idle descent, especially for some of the fancy-schmancy STARS in to SEA.

 

Sometimes we get it. Sometimes we don't. I've never thought, "Man, those descent winds really made a huuuuge difference!" Sometimes we need a little speedbrake, sometimes a little throttle. That's with and without the DESC FORecast.

 

I just don't think the RW jet is as slippery as NGX.

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Sometimes we get it. Sometimes we don't. I've never thought, "Man, those descent winds really made a huuuuge difference!" Sometimes we need a little speedbrake, sometimes a little throttle. That's with and without the DESC FORecast.

 

Right, but the difference between the average simmer and a pilot on the thing is that you know where it's just the nature of the aircraft, and where it's an issue of the coding.  Moreover, a real pilot also generally tends to just take over manually (or operate in a different mode), rather than hopelessly let VNAV try to sort everything out.

 

Simple things like ensuring the throttles aren't interacting improperly (if the person uses the options to allow their hardware to override at certain times or always), starting the descent a little late, descending with high tail winds with no forecast entered, and so on, could easily mess up the VNAV profile.  A real pilot would know what to do with that.  In my experience, most simmers don't.  That said, arming people with as much information as possible to then pass onto the aircraft (namely the DES FORECAST), should help to avoid some of the issues that people often struggle with.  That's more of what I was getting at.

 

I often descend without them simply because I can't be arsed to go find the info on some of the shorter flights, or simply because I'm feeling lazy that day.  Usually, it has little to no effect on my flights, but I'm also mindful that it might affect it slightly, which may require a little SPD INTV or thrust to get things sorted.

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I saved my flight at the T/D and done about 8 of them last night untill i got a technique and eleminated those messages and arrived at my FAF alt with no worries all i can say its hard work getting her to slow down! I was deploying flaps 5 below 10k and getting my speed down accordingly. Is this what its going to be like all the time? Its going to be hard anticipating this because i only knew to slow down because i done it about 9 times lol so am i just going to be looking for messages on the CDU and act ?

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so am i just going to be looking for messages on the CDU and act ?

 

Somewhat, yeah, but you should also just pay attention to the whole picture.  Watch your speed, and watch the vertical profile on the ND.

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Is this what its going to be like all the time?

Not really. Some are as easy as falling of a log. Some are almost impossible. Most are in between the extremes. Just do what Kyle says in post 9.

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I saved my flight at the T/D and done about 8 of them last night untill i got a technique and eleminated those messages and arrived at my FAF alt with no worries all i can say its hard work getting her to slow down! I was deploying flaps 5 below 10k and getting my speed down accordingly. Is this what its going to be like all the time? Its going to be hard anticipating this because i only knew to slow down because i done it about 9 times lol so am i just going to be looking for messages on the CDU and act ?

You shouldn't need to deploy flap 5 as a speed brake like that. I wouldn't normally go flap 5 until decelerating on the ILS intercept leg. For most of your descent below 10000 you can maintain 240 or 250 knots. Deceleration to approach happens much nearer the destination. The FMC will display decel points on the ND.

 

Keep practicing and if necessary give yourself a bit more room for a level deceleration by descending early.

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Vernon

 

Yesterday, I stumbled across a different way (for me a least) of controlling descent speed It worked yesterday but that could have a fluke. I need to try it several more times to see if works out with headwinds, tailwinds, crosswinds, etc. I will let you know what happens.

 

Always pay attention to what the plane is doing and try to stay on top of it. Just because it is on AP doesn't mean you can forget about until it's time to intercept the localizer and glideslope. This plane takes constant vigilance during descent.

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thanks mate kinda getting the idea of that lol at first i thought stick it in vnav and it'll get you down of course it will but not at the correct height and speed lol

 

i found this - 

 
Crosschecks can be done at 20,000, 10,000, 5,000, 4,000, 3,000
your height/1000*3 is 10 less than your distance to go when above 10,000' you're good.
 
 
can i start using these? 

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can i start using these? 

 

Sure, but you already have a VNAV path indicator giving you pretty much the same information.  That crosscheck method is something pilots used back in the days of the 707 and 727.

 

I think you're making this a lot more difficult than it needs to be.  The solution here is paying attention to the plane and adjusting your path by either increasing the flight path angle (by using SPD INTV) or decreasing the flight path angle (by adding thrust).

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Is spd intv and thrust not the same and both increase the FPA?

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