Sign in to follow this  
Gregg_Seipp

Noob question: Arrival speed/flaps questions

Recommended Posts

After a lot of angst about which big-iron plane to get, I finally picked up the 777 the other day.  Eager to get it flying, I went through tutorial 1...a fair amount to absorb but it went quite well.  I'm working on 1.5 now but have some basic questions about arrival, especially about flaps and speeds.  (I'm guessing it's covered somewhere in that mountain of documentation which is still piled on my virtual desk but here goes...)  Setting aside that there will be speed and altitude restrictions on STARS in addition to instructions given by ATC,

 

  • What does ATC typically do when you're at cruise...tell you to "descend at your discretion to XXX"?  How do they interrupt VNAV descents typically?
  • What rules of thumb do folks use for flap/speeds when preparing for arrival?  E.g. you're X miles out, time to start slowing this plane up.  It's heavy and slick so I'd think early is important.  You may be in a decent as well which will muck things up...spoilers?
  • I'm assuming that you deploy the flaps and then, generally, immediately dial speed down to the flaps maneuvering speed.  E.g. "Flaps 5" and then dial the speed down to the flaps 5 flag on the speed bar...wash, rinse, repeat down to landing flaps.
  • Are there flaps limit speeds?  Case in point, I had the speed restriction of 210 at a fix on the tutorial and I hit the green circle but my speed ended up being 10 knots high at the fix.  I didn't deploy flaps 1 at first because I was still above the "Up" tick.  When is it safe to deploy them?  I was still on VNAV...should I have pressed the speed button and dialed it down to 210?
  • Seems like at most airports they let you fly the STAR and then, almost invariably, pull you off for vectors.  That mostly true?  It seems to be what I'm hearing with live ATC.
  • I see posts from time to time about manually flying the approach.  Do most RW pilots do that?  If so, do they also disengage the autothrottle?  On the other hand, having watched this plane do its autoland and literally *nail* the thick captain's bars (I *always* float past them) showed me something.

Overall, I'd have to say I like the 777 more than the 737 which is rare because it always takes me a long time to warm up to a new plane.  On the other hand, the 737 was my first big iron and everything about it was new and confusing.  I didn't fly the NGX much but there's a lot that's familiar that carries over this time.

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

  1. What does ATC typically do when you're at cruise...tell you to "descend at your discretion to XXX"?  How do they interrupt VNAV descents typically?
  2. What rules of thumb do folks use for flap/speeds when preparing for arrival?  E.g. you're X miles out, time to start slowing this plane up.  It's heavy and slick so I'd think early is important.  You may be in a decent as well which will muck things up...spoilers?
  3. I'm assuming that you deploy the flaps and then, generally, immediately dial speed down to the flaps maneuvering speed.  E.g. "Flaps 5" and then dial the speed down to the flaps 5 flag on the speed bar...wash, rinse, repeat down to landing flaps.
  4. Are there flaps limit speeds?  Case in point, I had the speed restriction of 210 at a fix on the tutorial and I hit the green circle but my speed ended up being 10 knots high at the fix.  I didn't deploy flaps 1 at first because I was still above the "Up" tick.  When is it safe to deploy them?  I was still on VNAV...should I have pressed the speed button and dialed it down to 210?
  5. Seems like at most airports they let you fly the STAR and then, almost invariably, pull you off for vectors.  That mostly true?  It seems to be what I'm hearing with live ATC.
  6. I see posts from time to time about manually flying the approach.  Do most RW pilots do that?  If so, do they also disengage the autothrottle?

 

  1. Either "Descend via the [sTAR NAME]" or "Cross [FIX NAME] at [ALTITUDE]," or "Descend and maintain [ALTITUDE]." If any of those altitudes use local pressure and not standard, you will get an altimeter setting as well. VNAV is interrupted as little as possible. Contrary to what you might expect, a controller doesn't want to add more workload to either of you. Interrupting a pilot's own path is adding workload to both.
  2. I just adjust to the situation. I'm sure someone else will have a rule of thumb for it all.
  3. Somewhat - depends on the situation. Ideally, you don't want to back up everyone behind you, so you wouldn't want to just start dropping the speed without giving a thought to speed in relation to how far out you are.
  4. Yes. See the flap speed placard by the gear handle.
  5. In the States, most facilities do this. It's used mainly to help spread the load across multiple runways, or adjust for speed differences. Longer vector means I don't need to tell you to adjust your speed for the slower guy ahead of you.
  6. There's a commonly held belief - for some odd reason - in the sim community that quite a number of approaches are flown by automation. This is simply not true. Coupled approaches are actually quite rare, particularly in the case of autoland. Most approaches are hand flown, particularly when it's a visual approach. For the 777, Boeing recommends that the A/T remains on at all times.

To clarify the above, since it can confuse people:

  • Descend Via - allow the aircraft to descend on the VNAV path that complies with the restrictions of the STAR. Used for "profile STARs," or STARs with multiple altitude restrictions (most of the current STARs), such as the HYPER6 into IAD. May be used with a modifier of "...Except Maintain [ALTITUDE]," which requires you to level off upon reaching a particular altitude, complying with the restrictions until that point.
  • Cross [FIX] at [ALTITUDE] - allow the aircraft to descend on the VNAV path that crosses a fix at an altitude. Used primarily for older style STARs, or STARs with one or two fixes with a single crossing restriction, such as the COATT4 into IAD.
  • Descend and Maintain - descend from your current altitude with no delay to the altitude specified, disregarding any other altitude restriction, unless "comply with restrictions" is added to the end of the instruction. Used primarily in when a STAR isn't filed, or there is no reason to comply with restrictions (midnight shift, as an example). May be used with a modifier of "...comply with restrictions," in which case, it would be much like the above "Descend via ... Except Maintain [ALTITUDE]."

Share this post


Link to post
Share on other sites

 

 


Cross [FIX] at [ALTITUDE] - allow the aircraft to descend on the VNAV path that crosses a fix at an altitude. Used primarily for older style STARs, or STARs with one or two fixes with a single crossing restriction, such as the COATT4 into IAD.

 

Just to be clear, does this mean you can continue descending after the fix?

 

 

 


May be used with a modifier of "...comply with restrictions," in which case, it would be much like the above "Descend via ... Except Maintain [ALTITUDE]."

 

So, this means to fly the STAR except when you get down to [ALTITUDE], stay there.

Share this post


Link to post
Share on other sites

 

 


Just to be clear, does this mean you can continue descending after the fix?

 

Some facilities say "...at and maintain [ALTITUDE]," to avoid confusion, but no - do not descend unless given some other direction.

 

What's going on in the background here is that the center facility is given permission per a letter of agreement with the TRACON to give you that instruction, which is likely in the TRACON airspace. You will be passed to the TRACON well before reaching that, and will likely get a descend and maintain instruction prior to that.

 

As an example, the COATT4 STAR into DCA has you crossing FALKO at 10000. Wash Center will say "cross FALKO at 10000, 250 knots." They will then hand you off to the TRACON at some point before you reach FALKO, and Potomac will give you an instruction similar to "after FALKO, descend and maintain 6000."

 

 

 


So, this means to fly the STAR except when you get down to [ALTITUDE], stay there.

 

Correct. Fly the STAR, complying with the various altitude restrictions until that point, and stay at that altitude while following the lateral direction of the STAR.

Share this post


Link to post
Share on other sites

I'm assuming that you deploy the flaps and then, generally, immediately dial speed down to the flaps maneuvering speed. E.g. "Flaps 5" and then dial the speed down to the flaps 5 flag on the speed bar...wash, rinse, repeat down to landing flaps.

Are there flaps limit speeds? Case in point, I had the speed restriction of 210 at a fix on the tutorial and I hit the green circle but my speed ended up being 10 knots high at the fix. I didn't deploy flaps 1 at first because I was still above the "Up" tick. When is it safe to deploy them? I was still on VNAV...should I have pressed the speed button and dialed it down to 210?

 

Hi, Gregg,

 

My own practice flying a STAR in LNAV/VNAV, FWIW, is to use the speedbrake to maintain the FMC-indicated speed.  The autopilot will adjust pitch and thrust as best it can to meet both speed and altitude restrictions, but if the aircraft is descending on the prescribed vertical path and is still too fast w/ throttles at idle or HOLD, speed brake is necessary.  I don't deploy any degree of flap until the speed is below the maximum speed for that setting (indicated on flap placard).  The 777 does have flap relief, which means it won't allow the flaps to increase when the speed is too high (and even will retract flaps if the speed gets too high after flap deployment) but I don't think it's good practice to rely on that to avoid flap damage.   I tend to exchange flaps for speed brake -- as the plane slows down I extend flaps as necessary and as speed will allow to keep the speed to the target, and use the speed brake less.  (You can see the autopilot's target speed on the PFD to the upper left.) 

 

Regarding flying the approach manually, I usually shut off the autopilot on final and hand fly the landing, leaving the autothrottles on (different from 737NG and 767 based on Level-D's simulation).  A RW A320 pilot told me he does the same thing, and if anything the A320 is more automated than the 777.  As many others have said, it's good practice to hand fly the entire approach (or entire departure) occasionally to keep skills up.  One thing it took me awhile to discover: if the autopilot is off but LNAV/VNAV and autothrottles are active and the FDs are on, the autothrottle will still adjust thrust as if the autopilot were on.  For example, on takeoff the preset TOGA thrust will be set, and then it will switch to max CLIMB thrust at the appropriate altitude; then thrust will be reduced as you reach your initial target altitude.  You just follow the FD pitch bar (but if you don't follow it you will likely overspeed as the autothrottles are expecting you to pitch up until close to target altitude). 

 

One other point: unlike the 737 NG, the 777 FMC does not set the final approach speed on the legs page, so it is necessary to manually intervene on final to set the final approach speed (adding 5 knots) calculated by the FMC.  Also, sometimes the speeds allowed by the FMC as you get near the final approach are just too high, especially if you are having trouble descending to meet a speed and altitude restriction.  So it is necessary to intervene on the speed.  And of course ATC may tell you to do something different both as to speed and course.

 

I'm sure Kyle will correct me if my procedures have any weak spots!

 

Mike

Share this post


Link to post
Share on other sites

 

 


What rules of thumb do folks use for flap/speeds when preparing for arrival?  E.g. you're X miles out, time to start slowing this plane up.  It's heavy and slick so I'd think early is important.  You may be in a decent as well which will muck things up...spoilers?

 

My rule of thumb is...check the runway elevation on the LEGS page. Add 4000 feet to that. This is the altitude at which I want to have my flaps extended to flaps 1 (v ref + 5 + 80), and then work your way down speed-wise. Another thing I follow is at 40 miles away from the airport I want to be at 10000 feet flying 250 knots (a common restriction as you know). If at any point the plane can't slow down, I use spoilers.

 

Hope you're enjoying the 777!

Share this post


Link to post
Share on other sites

My rule of thumb for flap extension is based on the schedule given in the FCTM, page 5.7.

 

At the end of descent, at the height I will approach the ILS at, I decelerate to the manoeuvre speed labelled "UP" in green on the PFD speed tape. On the localiser intercept course I select flap 1 and decelerate to "1" on the speed tape. When getting near localiser capture I select flap 5 and decelerate to "5". After localiser capture and as the G/S pointer starts to move down I select Flap 20 and gear down and decelerate to "20". When established on the ILS I select VREF+5 and landing flap.

 

Some approaches require you to maintain a higher airspeed until a certain DME distance on the ILS. In that case I still select landing flap but maintain the required speed, selecting VREF+5 when allowed.

 

You could simply select VREF+5 and successively select the next flap stage as IAS decreases to the appropriate flap speed bug, but that might mean you decelerate too soon.

 

I recommend reading the FCTM as that lays out the approach procedures and flap/gear schedules very clearly in diagramatic form.

Share this post


Link to post
Share on other sites

 

 


My rule of thumb is...check the runway elevation on the LEGS page. Add 4000 feet to that. This is the altitude at which I want to have my flaps extended to flaps 1 (v ref + 5 + 80), and then work your way down speed-wise. Another thing I follow is at 40 miles away from the airport I want to be at 10000 feet flying 250 knots (a common restriction as you know). If at any point the plane can't slow down, I use spoilers.

Hope you're enjoying the 777!

 

Very useful.  Seems like good guidelines.

 

 

 


My rule of thumb for flap extension is based on the schedule given in the FCTM, page 5.7.



At the end of descent, at the height I will approach the ILS at, I decelerate to the manoeuvre speed labelled "UP" in green on the PFD speed tape. On the localiser intercept course I select flap 1 and decelerate to "1" on the speed tape. When getting near localiser capture I select flap 5 and decelerate to "5". After localiser capture and as the G/S pointer starts to move down I select Flap 20 and gear down and decelerate to "20". When established on the ILS I select VREF+5 and landing flap.

 

Seems reasonable.  I am, maybe, a quarter of the way through the FCTM.  Lots to learn.

Share this post


Link to post
Share on other sites

 

 


Seems reasonable. I am, maybe, a quarter of the way through the FCTM. Lots to learn.

It's the best way if you have time. 

 

One other thing, the amber speed band that extends below the red upper speed limit on the speed tape shows you where the red upper limit speed will be at the next flap position. As long as your current airspeed is below that amber band you can safely extend flaps one notch.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this