Deceleration

[Expert]

Could anyone enlighten me as to whether when issuing a speed reduction clearance, e.g. a/c maintaining 300kts in the descent and asked to "reduce speed 220kts", you guys are expecting a particular deceleration rate from us guys?

[375ml]

1.27kts per second reduction thankyou.

[j17]

Expert

As an approach radar controller if I request a speed reduction I would expect it to attained within the normal decsend profile.If you cannot do this for what ever reason expect a heading , which will widen your radar circuit out . Dont try and buck the system play the game , its to everybodies advantagt

[cossack]

j17
I don't think he's trying to buck the system but making a legitimate enquiry, unless I misunderstand you Expert?

If you're doing 300kt in the descent and are asked to slow to 220 we know you're ROD will reduce and should vector accordingly. It will take a long time to get rid of 80kt and keep the same descent profile, probably longer than your intermediate approach will give you.

If the controller wants you to slow down quickly that should be specified in the clearance. A normal rate of speed reduction IMHO would be one that can be achieved by your aircraft type without use of speed brakes or resorting to level flight.

[Cryolosophorous]

Bingo! Ditto Cossack :)

[followme]

We can't specify any particular decelaration rate as we can't be familiar with all different a/c performance in this respect. We rely on literature and experience to know general acceptable speeds for bands off a/c. We wouldn't expect air brakes on, gear down and arms out the window just a sensible reduction. If an extreme deceleration is required, where wider vectors are not the best option, this will be specified...if this is not possible plan B will be formulated....quickly.

:cool:

[Expert]

Thanks to all & yes, you did understand me correctly cossack, I was not trying to buck the system.

The answer here seems to be to continue doing what we have always been doing. Maintain an awareness of traffic around you and adjust your normal deceleration, if required, subject to the urgency of the situation/controller's clearance. This tends to work great in the more "sophisticated" ATC environments, however, one's situational awareness can easily be shattered when instructed by one controller to maintain high speed only to be given an 80/100 kt speed reduction and delaying vectoring by the next guy! I can think of certain Far East airfields who tend to do that, I would have thought that an earlier management of descent/approach speeds would make life a lot easier for all concerned!

By the way 375ml, where does your 1.27kts/sec come from?

:)

[Wheelybin]

Expert,
just a quick aside. Agree with previous reply's (particularly Cossack,Mrs Wheely says Hi).
The way we are taught is that you vector to achieve separation then speed control to maintain that separation. Therefore experience of watching green luminous maggots means we have a rough idea of how long that deceleration will take to achieve.
This can , unfortunatley, lead to a "one size fits all" situation, but constant monitoring means we can hopefully adjust flight paths to achieve the desired result.

[FWA NATCA]

Expert,

Vectors are used to obtain appropriate seperation and speed control is used to maintain it, since most airplanes can't slow very well as they are descending I will not normally give you a descent and a speed restriction at the same time, unless it doesn't really matter. If I need both then I will phrase the request as: reduce speed to XXX then descend and maintain XXX.

Mike

[C Yeager]

What is interesting to note for all ATC's ...and I speak under correction .....is that there is a clear ratio between priority given (by the auto pilot) to slowing the a/c down VS descending the a/c .....that is of course during autopilot operation and could be influenced accordingly by the crew ....bottom line is .....ATC's should know their "customers" limitations / operating parameters ....and work around them ..... ie. don't expect the impossible ......
I f we all take time to fully understand each others restrictions / operating parameters ...then we WILL work in greater harmony

[Scott Voigt]

C Yeager;

Knowing the aircraft is indeed important. However, we have seen over the last decade that pilots are letting the aircraft systems do everything even when it is to the detriment of getting clearances adhered too... I fear that we are getting away from flying the aircraft and are spending much to much time managing the systems...

regards

[West Coast]

Scott
That is the idea behind automation on our end. The auto flight system can do a better job of smoothly, accurately, and econonically flying the plane than I can. What it also allows is for my SA to go way up. I can better manage ALL aspects of the flight with george flying. If a crew misses restrictions or what have you, its an error to manage, not a problem of automation.

[Scott Voigt]

West Coast;

Yup, when everything is working just fine the automation does well... However, when we need you to do something, we don't need to wait a couple of minutes while you are programing. It has also been featured in more than just a few incident and accident reports that the crew was no longer prepaired for the airmanship that was needed when the automation was no longer working as advertised... You don't use the skills they atrophy. Shoot, watching someone either on the flight deck or from behind the scope when asked to do something and then watch what happens when they have problems getting the FMS to do what they want it to do... It's almost like an emergency to them to have to fly raw data...

regards

[buttonmonkey]

Scott,

I think you missed Westcoast's last point, that with the automatics in and the crew misses the restriction, it's a problem of systems management and not a problem with automation. The time for head down programing the box is way back prior to top of descent, 99% of a requests from ATC can be accomodated through the crew making a selection on the FCU which should only take moments to exicute. Sure, on the 1 in 10,000 occasion that the aircraft isn't doing what it's suppose to (there are the very occasional software problems) then sure the automatics come out and the deviation corrected. We all practice raw data descents and approaches when the conditions are appropriate. as you say use it or lose it. However descending at 300kts, raw data, into a busy terminal area greatly increases the chances of missed clearances. It's all about increasing the safety margins. Any crew having problems getting the FMS to do what they want it to do, should dust off their manuals........

[Scott Voigt]

Button Monkey;

I'm sorry I just don't agree... I see MANY non automated crews flying around the system and they do just fine in flying the aircraft. If anything, I see the automated crews as being busier than most of the non automated crews when it comes time to work close in... I have been on MANY jump seats, in many level D sims and have done my own flying to know what the work load is... Some folks completely forget what they were able to do long ago when they were flying no automation in a single person cockpit. Now THAT is workload... <G>

regards

[West Coast]

Scott
For purposes of spacing and sequencing ATC has the big picture
there is however alot more you don't see that all adds up to a safe flight, compliant with all requirements placed on myself and my crew. You may see a 727 executing the same clearance as a 4th generation EFIS/FMS equipped aircraft on your scope, draw no conclusions from that. I recently transitioned from a steam gauge aircraft to a highly automated one. My ability to fly the same STARS/DP's, etc as I did in the jurassic jet while maintaining a much higher SA has shot through the roof. It is transparent to you, but night and day to me. Remember that ATC is but one aspect of a safe flight from A to B (a very important one) and that automation is another tool that aids in areas you don't see.

Don't fall into the trap of 3rd seat observations. Many moons ago
I was a controller in the military, and for a short while as a DoD controller. I have come to the conclusion that only gave me a flavor for what is going on, not any innate knowledge of the ATC system. The JS, sim or GA flying cannot prepare you to fully comprehend what we are doing, no more than my limited ATC experience and current interaction with controllers allows much insight into your job.

As to the raw data comment, that still has me scratching my head.

[Scott Voigt]

Hi Westcoast;

I was not just looking at it as a jumpseater, but someone who also has an instrument, multiengine and commercial rating... Been there and done that...

regards

[West Coast]

Those ratings and a thousand hours might get you a job flying a piston powered lance hauling checks at night. If you think having the most basic of ratings of a professional pilot allows you to comment with an authoritive voice on airline operations, you are mistaken. You have more in common with airline pilots because you are a controller than a pilot. Once many moons ago, I was an entry level pilot, I believed I had a grasp on airline flying because of flying air ambulance for years, I was wrong as are you.
Your posts in other threads impress me because your opinion is based upon seemingly vast experience working the ATC system.
Even if I disagreed with you, I could find a common ground. Here however your arguement is clouded by the inference that weekend flying in a C172 or perhaps a C310 differs little from an airline gig.

[Bigmouth]

I agree with Mr. Voigt on this one.
Hand flying becomes second nature when George is not installed, you don´t even have to think about it after a while. And your head-to-hands/feet neurons allow for a much quicker controll input than old G.
I used to be a decent stick, now I suck thanks to AP and company SOP´s.

[West Coast]

Yup
My raw instrument skills are not what they used to be when I flew the Beech 1900 sans AP. Flying a large airliner is a different type of flying, it took me awhile to grasp that. A pilot who flies a complex jet is a manager as much as a manipulator of the controls. By virtue of getting hired, I proved my instrument skills in the hand flying arena. I am at peace with the concept that the AP and automation do the mundane flying, allowing the crew to manage. I kick off the AP&FD when it is appropriate, but I recognize my focus narrows somewhat to the PFD/MFD, my overall SA goes down. There has to be a reason all this stuff was put on the flight deck to begin with, and I guarantee it wasn't done to allow you and me read the paper in peace. I t was put there to increase the level of safety, and it has done just that.
The price pilots pay for this increased level of safety is the initial transformation from a pure pilot to a systems manager.

[FWA NATCA]

Like Scott, I've taken many rides in the Jump Seat, but I don't hold any pilot licenses, so each time I take a FAM I ask questions. Some of the questions I ask most often are:

1. How slow can you fly on final with everything hanging out.
2. How fast can you fly on final with everything hanging out.
3. What are your climb and decent rates best and average.
4. How quickly can you slow when given a speed reduction, level flight and during the decent.
5. In an emergency how can I best help you.

Being an approach controller I'm working hard to vector you around, over, and under other arrivals, departures, and over flights, as well as trying to establish and maintain a final. When I ask for a speed reduction, I need it now, not 5 minutes from now.

Safety is a team effort.

Mike

[West Coast]

Excellent questions to ask. You might consider asking about manuevering at slow speeds and altitudes on departure. At a few airports we are asked to make tight turns shortly after departure, and our airspeed, or lack of it affects our turn rate/radius. Ask them to show you how to program the FMS for arrival/approach changes. Ask how wx affects the aircraft, ie anti ice robbing power from the engines. Ask about special departure procedures for an engine failure. If you are not already familier with them, they are proceedures that guarantee us to avoid terrain on a single motor. At SLC our proceedure has us turn left 320 off 34R right into traffic off of 34L. Your hands will be full getting traffic out of our way as we do something that may not even be close to the DP, and might in fact be a confliction with other traffic.
A bit more of a center thing but ask how important they consider ride reports on the route ahead, while somewhat for pax comfort, we don't want to hurt the FA's in the back. We can sit them down if it can't be avoided, but we have to know about it. Ask about wake turbulance avoidence techniques for the commuters/regionals. Ask about going down/slowing down at the same time, it can be done to a certain degree, alot of guys don't like to pop the boards for ATC, but the capability is there.

I agree with you, 5 minutes is a long time to slow. Our general rule is 1nm/10kts reduction in level flight, from our profile speed of 320 to slow to 250 takes 7 miles
Keep asking questions, the more you know about how we operate, the better off we all are.

[buttonmonkey]

Scott,

Sorry, been working and making sure the automatics got put to good use. I am sure you are just playing devils advocate on this one for the sake of sparking up a lively debate, otherwise i'd be mildly concerned that yours are the views of a SAFETY and TECHNOLOGY chairman! Using your experience and the technology available to avoid being placed into a situation requiring a high workload, leaving plenty of spare mental capacity and thereby increasing safety, seems the sensible way to go to me?