mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

Speedbrake On Descent

Sun Jan 06, 2002 4:11 pm

During the descent, on FMC/autothrottle equipped airliners, if the rate dialed in exceeds that achievable with the throttles at idle, is there warnings/advisory message from the FMC to let the pilots know to deploy the speedbrakes, extend gear, or lower flaps?
 
ewr757
Posts: 354
Joined: Mon Apr 03, 2000 8:47 am

RE: Speedbrake On Descent

Sun Jan 06, 2002 9:17 pm


It will say "Drag Required", With a EICAS (center display screen) FMC Message as well (B757/767).

Nothing is "dialed in" (I'm assuming you meant from the pilot) on a VNAV coupled descent. The FMC predicts the path (with/without a given speed) and it is all automatic. Any "dialing" changes the mode from the A/P to follow the predicted path.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Mon Jan 07, 2002 2:21 am

By "dialed in", I was thinking of situation when ATC requires a "slam dunk" after keeping you high and fast on the arrival. In that case, would you still keep the plane on autopilot and select the required rate of descent to match ATC requirement?
On approaches to LAX, I always see speedbrakes used so I figure it must be due to ATC. Theoratically, the pilot can plan his approach so speedbrakes would not be required.
Drag required: does flaps help? Is there different detents on the speedbrake or is it a gradual/continuos deployment? Does the pilot just "eyeball it" or does he keep it extended until the message goes away?
 
ewr757
Posts: 354
Joined: Mon Apr 03, 2000 8:47 am

RE: Speedbrake On Descent

Mon Jan 07, 2002 3:25 am

The problem with flaps is you have to slow down to extend them. The airplane descends much faster at a high speed, clean wing configuration. A speed that is greater than Flap ops. speed.

LAX ........I've flown those arrivals probably 200 - 300 times. The boards need to be extended after ATC gives a speed restriction slower than what was pre programmed or assigned. Even in a clean configuration the profiles into LAX are difficult to meet since there are varied crossing restrictions (without the boards).

Technically you're right you wouldnt need the boards if winds or speeds didn't change, but that doesnt happen in day to day ops. Especially with the amount of traffic into large airports like LAX.

There is a PDI (path deviation indicator) on the HSI (map mode) or (ND) which shows how high or low you are on the programmed VNAV path. You adjust drag accordingly with the boards or you can also program a higher speed (if there is no restriction or assignment) and that will get the aircraft down on the profile as well.

Does this help?

 
Guest

RE: Speedbrake On Descent

Mon Jan 07, 2002 3:45 am

To go along with what the other guys have said about flaps, on some aircraft there is a maximum altitude for the operation of slats and/or flaps. In the aircraft that I am presently flying it's 20,000 ft. In those cases, the boards are you only option. Also, no one has mentioned the occassional need to use both the boards and power at the same time - to keep the bleedair up for deicing.
 
ThirtyEcho
Posts: 1409
Joined: Tue Jan 01, 2002 1:21 am

RE: Speedbrake On Descent

Mon Jan 07, 2002 4:14 am

Opening the doors on a 172 can give you a high sink rate with no speed buildup but only if you have a front seat passenger willing to open their door, too. Otherwise, you get assymetrical speed brake deployment. OK, I'll shut up.
 
777236ER
Posts: 12213
Joined: Sat Aug 18, 2001 7:10 am

RE: Speedbrake On Descent

Mon Jan 07, 2002 6:29 am

Not to mention there are speedbrake limits too  Smile Certain 738s have/had a 350kt limit after an in-service 738 expierence buffeting after deploying them at very high speed.
Your bone's got a little machine
 
SkyGuy11
Posts: 532
Joined: Fri Oct 26, 2001 7:09 am

RE: Speedbrake On Descent

Mon Jan 07, 2002 9:00 am

Thanks thirtyecho. You can also open the windows and stick your hands out to slow the thing down, just be ready on the rudder for the asymmetrical drag. Spins are a great way to lose altitude fast as well. You can also try a knife edged descent in which you flip the plane on its side, keep it upright using rudder (it acts as your elevator in this case), and descend. You're gaurenteed to pin the VSI every time. Ok I'll shut up too.
.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Mon Jan 07, 2002 10:35 am

Thanks everyone..esp EWR757 for the info....
BTW, which one do you like flying more....757 or 767?
Also, does the 767-400 have it's own type rating and crew roster from the other 757 and 767's?
What about 757-300?
 
ewr757
Posts: 354
Joined: Mon Apr 03, 2000 8:47 am

RE: Speedbrake On Descent

Mon Jan 07, 2002 11:39 am



I like the 767 since it pays more.

Flying wise, it doesn't matter to me, they are both great airplanes.For the mission each aircraft does they are superb in both performance (764 is a little light in the power department) and flying qualities.

We fly all 4 airplanes with the same pilots. Type rating is common but there are currency requirements for the 764 differences within a 6 month time frame. You could be scheduled to fly a 752 and show up to see a 762 or 764 for an equipment substitution. That is the beauty of the common type rating.

I have not flown the 753 yet. I am scheduled to fly one later this month.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Mon Jan 07, 2002 2:44 pm

Is the 753 identical to the 752 in terms of systems and cockpit layout?
Is the 764 (despite the 777 style layout)much different in terms of systems and operating procedure from 762?
Is there difference in takeoff rotation technique between the 752 and 753 in order to prevent tailstrike?
Side question...which city has the worst smog problem as far as spotting traffic is concerned? Is it LA or Houston? Or another city?
Thanks
 
ewr757
Posts: 354
Joined: Mon Apr 03, 2000 8:47 am

RE: Speedbrake On Descent

Mon Jan 07, 2002 10:30 pm



Good question about the differences. 752-753 are identical with cockpits and systems. 762 is as well with the exception of a couple extra switches and systems very similar with few changes.

764 although cockpit layout like a 777, the systems are nothing close and that is the logic for the common type with the 757.

764 762 systems nearly identical. It really isnt a problem switching from one to another.

Rotation. I dont have my manual for the actual tail clearances but the 753 rotation is like the 764...sssssssssllllllllllllllloooooooowwwwwwwwwww.

Smog? MEX is the worst, no GA traffic though to speak of. LA is one of the worst but not as bad as IAH. LA seems to be consistent with the smog problem with the terrain I would assume.

I had a near miss going into LA near PDZ VOR years ago. My only comment to the Beechcraft was that he needed to clean the oil streaks off the belly of his airplane. It was one of those MVFR days due to smog (haze). LAX was 1 1/2 at the time.


 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Tue Jan 08, 2002 6:39 am

Is TCAS a big help when flying around LAX or IAH where visibility is poor due to smog?
One of my biggest worries about flying in SoCal is midairs and biggest dislikes is looking for traffic that is hard to spot due to smog. Have you ever had any close calls with GA traffic out of Hawthorne while on approach to Rwy25 at LAX?
Any advice on spotting traffic?
Which airline has the most visible paint scheme and which one has the least visible (as far as being seen in poor visual conditions). I personally think United has got to be one of the worst with that grey background. What were they thinking?? Also it could easily be mistaken for a military aircraft.
 
SkyGuy11
Posts: 532
Joined: Fri Oct 26, 2001 7:09 am

RE: Speedbrake On Descent

Tue Jan 08, 2002 8:43 am

From my experience, you really cannot tell the paint scheme of airliners when looking for them. If you can, you're already too close. They just stand out as a sillouhete (I can't spell) against the sky or ground. Lights help alot.
.
 
ewr757
Posts: 354
Joined: Mon Apr 03, 2000 8:47 am

RE: Speedbrake On Descent

Tue Jan 08, 2002 11:15 am



No problems with Hawthorne. TCAS is invaluable and very accurate.

UAL is tough to spot on hazy days, but from a distance nothing is easy to find. Although the SWA with that corndog paint scheme seems easier to spot than most others.

Keep scanning the sky by sections in the windscreen and always keep looking out the windows, up down, left right.....never stop. Make your visual scan for traffic as spirited as your instrument scan under IFR conditions.
This has saved my rear end on more than one occasion
 
Guest

RE: Speedbrake On Descent

Tue Jan 08, 2002 11:19 am

Well said, Captain. I'll go ahead and say it though, TCAS is great aid, but it wasn't meant to take the place of looking out the windows.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Tue Jan 08, 2002 2:23 pm

Thanks for your replies to my questions...I am sure to ask you some more at another time..
Have fun with 753....
 
ewr757
Posts: 354
Joined: Mon Apr 03, 2000 8:47 am

RE: Jetguy

Tue Jan 08, 2002 7:29 pm



I'm glad you said that about TCAS. I was thinking that but didnt convey that specific thought.

You're absolutley correct, it is only, and always will be an aid. Nothing beats the old Mark I type eyeballs.
 
cv640
Posts: 843
Joined: Wed Aug 30, 2000 8:10 pm

RE: Speedbrake On Descent

Wed Jan 09, 2002 12:31 am

As long as we have windows upfront, TCAS will never completely take over traffic avoidance. I do thibk its a wonderful help and hate flying when its deferred.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Wed Jan 09, 2002 3:18 am

Is it a lot less stressful/ lower workload flying into locations where there are no or very little GA traffic?
For example, NRT and MEX vs LAX and IAH.
Do airline pilots generally feel that GA pilots overall are currently getting adequate training and operating in a safe manner or do you think a lot of training requirement would be beneficial?
 
AM
Posts: 593
Joined: Sat Oct 02, 1999 8:49 am

RE: MEX

Fri Jan 11, 2002 3:38 pm

There is very little GA traffic flying over Mexico City compared to other cities since this kind of traffic can't fly into MEX, GA operates from airports in nearby cities like Toluca, Cuernavaca and Puebla. Anyway, there are helicopters flying all the time below arrival and approach paths. More than GA and helicopter traffic, what you have to look out for is departing traffic when you are arriving, and viceversa, since there are several departure and arrival routes "intersections".

And that's other thing about MEX. There are very few cases when your aircraft receives radar vectors. Almost always, you follow an arrival route that takes you all the way to the Outer Marker of the ILS approach in use. Mexico City is actually in a valley, so there are hills and mountains that restrict arrival and departure routes.

It is very unusual to monitor the ATIS and hear something different than "visibility 6 miles due to haze and smog". Smog is worse during morning hours, so vis. of less than 3 miles is very often from 6am-11am. But of course, we also have our clear days.

And then there's the classic Mateo 6 arrival. You get to the Mateo VOR (which is in the northern area of Mexico City) via an arrival transition or a direct routing, descend from 11000 to 9700ft, and fly on a 160° track. During 9.2 miles, you fly over the world's largest city from north to south. Watch for the helicopter traffic approach control told you about, which can't go above 8500ft. Then you cross the MEX VOR 248° radial, and start a left turn to intercept the final approach course to 05R of 052°. Your heading is 160°, so this is no easy turn. All this while descending to 8800ft before reaching the marker, 5 miles away from the runway. You can see the Mexicana Tower, the Cruz Azul Soccer Stadium and the World Trade Center to your left (if you're a passenger, not if you're sitting in the cockpit flying the plane). "Continue to 05R, altimeter 30.38, you are number 2 to land". The challenge here is to cross the marker at the correct altitude, and avoid the common localizer overshoot or undershoot. Even LNAV and VNAV modes can have trouble doing this. You are now over Plaza LOM, landing gear is already down. Final approach. Runway in sight? Not yet, expect visual contact in 3 miles. What about landing clearance from the Tower? No, they don't clear to land here until there's absolutely no kind of traffic operation on the runway before your touchdown. Landing flaps set, 2-mile final, 05R in sight. Autopilot disconnect (if you chose to have it engaged all the way to this point). "Cleared to land runway 05R, wind 080 at 5". 300ft above the airport's 7341ft elevation. Minimums. You cross the displaced threshold, and there's traffic on take off roll on 05L. 50, 40, 30, 20, 10... touchdown. Reverse thrust doesn't have the same effect here, on a high altitude airport, so it's harder to bring the airliner to taxi speed. "Exit to the left, hold short of 05L, traffic taking off".

That's a typical landing in Mexico City International. Hope I didn't bore anyone... The thing that has me confused though, is how I began talking about GA traffic, which is what was being discussed in the post, and I ended up describing the approach into MEX.

Regards,
AM

 Smokin cool
"... for there you have been and there you will long to return."
 
PPGMD
Posts: 2398
Joined: Sun Sep 30, 2001 5:39 am

RE: Speedbrake On Descent

Fri Jan 11, 2002 4:21 pm

Going with what ThirtyEcho was saying I have seen someone land with just pitch trim and doors. It requires alot of thinking ahead, clam winds, and a willing co-pilot/passenger.
At worst, you screw up and die.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

RE: Speedbrake On Descent

Sat Jan 12, 2002 3:02 am

My first flight instructor was an ex-Pakistani military pilot with excellent flying skills....while working on my PPL, he once demonstrated landing a C152 with just door and pitch trim at SMO (Santa Monica)....he was in the right seat. It wasn't the smoothest landing but I was very impressed.
 
lehpron
Posts: 6846
Joined: Tue Jul 10, 2001 3:42 am

RE: Speedbrake On Descent

Wed Jan 16, 2002 5:08 pm

Why doesn't the space shuttle's rudder speed brake come off during re-entry, would re-entry slow it down enough?
The meaning of life is curiosity; we were put on this planet to explore opportunities.

Who is online

Users browsing this forum: Baidu [Spider] and 23 guests