Ballistic Descent Clearances

[fireflybob]

Firstly please let me stress that I have the highest respect for air traffic controllers and the superb work that they do.

But from time to time we do get asked to perform miracles! In bound to a certain UK airport today on descent and then we get cleared to FL 100 to be level at XXXX when we have got circa ten miles to go to XXXX and we are going through FL 150 - read back clearance and said we would do our best and then ATC replied, ok be level at XXXX plus ten miles. We made this (just) but a bit uncomfortable for pax with speedbrake and high speed etc.

We are used to having to achieve certain levels as specified on the arrival (expect to be FL 70 by SLP or FL200 25 before Monty, for example, but being given late clearances such as this which are difficult to achieve can be challenging. Most operators also have a requirement to reduce rates of closure to 1,000 ft per min when withing 1,000 ft of a cleared level to avoid TCAS alerts.

I would be interested to hear ATCs side of this - thanks for any help.

[GM WAN TO BE]

Hi

Requests for last minute high rates of descent are not common operational practice, however on occasion's they are unavoidable. If I find myself in this situation, I would normally warn the pilot that after the conflicting traffic clears I will require a high rate of descent, just to get the crew ready for the executive instruction. Most importantly, if the 'level by' is unachievable then inform ATC, as hopefully plan B will be implemented.

Good luck

GMWTB

[thelowestlevel]

Descent clearences of this nature, are at times unavoidable, due to a conflict prior to, or after a cross, but a necessary part of the job.,

If you cannot make it, PLEASE tell us, as the plan that we have, is based on you doing what we would like you to do if at allpossible, if you cant we will change the plan. We are a fairly flexible lot, but there is nothing worse than a late notification of an inability to make a restriction as this can leave us with little time to change the plan, and some increased heart rates for a few minutes!!:ouch: :ouch:

The other side of this is that if the descent is given in plenty of time, to be level by a point, please be level, not racing down the last few thousand, as the previous few thousand were at less than 500ft pm. We dont give them unnecesseraly, and i know that early descents of 10000-12000ft can be unpopular, but are there to make restrictions with adjacent ACC's from LOA's, and there is little or nothing that we can do about them. Depending on the hour of the day the descents may be given earlier due to a lot of opposite direction conflicting traffic.

[Jumbo Driver]

The principle of "don't ask them to go down AND slow down" is understood by most ATCOs but it can still be overlooked at times. Expediting descent is in one sense the opposite of this, as speed and rate-of-descent are inevitably interlinked.

I believe there is a good point worth mentioning here and GMWTB touches on it in his post above.

If the need for a high rate of descent can be foreseen (e.g. after crossing opposite direction traffic) and we are warned, then we can prepare for it by reducing speed to min CRZ and then, when the descent clearance is given, a much higher rate of descent can be provided to fit the "plan" by increasing back to normal speed (or greater) to facilitate a higher rate of descent. We will then achieve the lower level more quickly - but maybe with an increased forward speed. In other words, if you can pre-warn us of an expedited descent and/or accept a higher forward speed on arrival at the lower level together with the necessary space for the subsequent speed reduction, then much greater flexibility is possible. Our, options of course become much more limited once flap extension has started on the approach.

Basically, it's all about conversion of P.E. into K.E.


JD
:)

[javelin]

Most times, if it isn't practical or sensible, I will ask, in plain language - why ?

Shannon wanted 270 - 20 before LIFFY this morning - the BSA is 270 AT LIFFY, I didn't have the spare fuel due to a load of pie eaters down the back on a long flight and we negotiated a compromise :ok:

I try and programme the worst of the restrictions into the box and then negotiate for better if possible.

[GM WAN TO BE]

Can someone tell me what BSA means?

Thanks

[ron83]

yesterday,on app to Schiphol,lady atco asked transavia crew to reduce speed to 230 kt and expedite descent,pilot answered something on dutch,unfortunately I don't speak it :} But I think she realized what she said,just after it ;)it happens sometimes

[thelowestlevel]

The max FL270 restriction at liffy is in the MACC SHA LOA and is there H24 for all traffic landing in the MACC TMA.

The restriction to be level fl270 20 prior to liffy is to ensure that you are level, and dont infringe on londons airspace on the descent. It also gives us a little bit of room with traffic climbing westbound. and EI departures that we have to fit into the mix.

These restrictions are a part of life, and unfortunately not popular at times with pilots and controllers.

The one thing i think that all of the restrictions have in common is that there seems to me, to be very little information on the ATC LOA's between the various ATC centres passed onto the airlines, often they seem to come as a surprise to the pilots when we give the restrictions.

Some restrictions, like the london TMA arrivals at or below FL330 at STU, can be lifted by local agreement between controllers, depending on traffic.

The upshot i think is that they are here to stay, and only increase in the future.

[javelin]

BSA - Block Standing Agreement.

As previously mentioned - levels to be at by - as decided between authorities.

The problem is, they are not published very well.

We get some profile guidance on the STAR plates, but these, further out restrictions you get to know by experience.

What whizzes me off is that I know the restriction is level at 270 by LIFFY - I don't want to be level 10 or 20 miles before LIFFY because it costs fuel. We are all expected to fly PLOG fuel, most of us fuel for a suitable arrival figure - say 7500kgs on an A330 in good weather, no hold, but if you have a combination of lots of pie eaters in the back, lower initial level out of departure airfield, no shortcuts etc etc, you end up a bit thin on this side of the pond and don't really want to do 270 - 20 before LIFFY :uhoh:

Luckily, the Shannon guys usually understand and we sort it out :D

[055166k]

Welcome to the modern ATC world. Training shortened to a third of what it used to be, and money rather than zeal-for-the-job as the main attraction.
Familiarisation flights almost non existent due to massive financial resources reserved for management courses and extra department creation schemes.
On a serious note......and this goes for other posters' points.....record these instances in the voyage report or at least tell the Chief Pilot. The more fuss you make the more likely a change will be forthcoming.
Fuel saving is supposed to be the flavour-of-the-month......the joke is that many restrictions....particularly level-capping and premature descent.... are written in one office, whereas the office next door is writing some peculiar procedure to save the fuel that the other guy has caused to be burnt.
Example: Airbus out of Bristol for Inverness probably burns third/half a ton more than Heathrow to Aberdeen.....one is capped at FL280, the other gets up to FL380. If it goes to Belfast, it is capped at FL240.
Exeter to Glasgow sometimes goes up to FL400, out of Bristol or Cardiff capped at FL260/280. Don't blame us...we only work here!

[fireflybob]

Thanks for all the replies.

My orginal posting was not to comment on BSAs etc (though relevant for debate maybe) but the occasional descent constraints which are announced very late such that we have to resort to more extreme measures to make same. Of course if you cannot make it you say so. We try our best whenever we can but when we are rocketing down at 5,000 fpm with the speedbrake out its not very pleasant for all concerned and with all the emphasis (rightly) on level busts this might be another hole in the swiss cheese model.

055166k, your points about less training and lack of famil flights is well appreciated. I think it is essential that pilots see your side of the job and also that ATC come and see our side but this seems to be less common.

[Token Sane Person]

...money rather than zeal-for-the-job as the main attraction.

Does that mean ATCOs are paid too much then, if the money is attracting the wrong sort of trainee? :confused:

[Radarspod]

Definitely (says an engineer :ok:)

[ImnotanERIC]

zeal for the job is almost irrlevant.
When I joined nats in 02 i thought that all big planes were boeings, and all little ones were cessnas. didnt really have an appreciation of what atc was. Saw it was big money, thought it sounded alright, good working hours etc. good leave allowance.
now I have been valid for a couple of years and do two sectors my knowledge has obviously increased as you cant avoid it when you are surrounded by aviation all day.
But, I don't think I would have had an easier time validating if i had spent my formative years at the side of a runway with a telephoto lens or played atc sims on my pc.
It is an aptitude for the job that should be looked for in recruitment, not how much they want to do it.
I really wanted to be something exciting like an astronaut or a footballer when i was ten. You don't always get what you want.
With the appaling wage we now offer our trainees, we are cutting out a massive pot of potential recruits. The likes of which have families/other commitments that mean they cant take the wage drop even if it would only be for a couple of years (as long as they dont get chopped at any 3 month interval).
I have heard people say that "at least they get a wage, trainee pilots don't."
Well Trainee atcos dont get to fly planes, they get to sit in a boscombe b&b reading the most boring manuals in the world in the hope that one day they can sit in a dingy room at 3 o'clock in the morning talking sh1t and eating crisps.
Why you want to apply shouldn't matter.

[anotherthing]

ImnotanERIC wrote:


I have heard people say that "at least they get a wage, trainee pilots don't."
Well Trainee atcos dont get to fly planes


Been there, done that and I can assure you, as far as I am concerned, being an ATCO is much more stimulating, especially with the advent of glass cockpits and huge automation.

Not taking anything away from pilots - it's whatever floats your boat - but I would not want to be a pilot for any money. One of the reasons people pay good money to become a pilot is the glamourisation of the job. I'm sure any pilot who is honest will admit that it's not exactly like that (in the same way life as an ATCO can be dull at times).

People will not come off the streets in big enough numbers to pay to become an ATCO because people do not understand what ATCOs actually do. Until NATS gets a grip and does some real PR, that will always be the case.

Realities of the two jobs aside even if the PR and knowledge was there, if Joe or Josephine Bloggs was given a wad of cash and told they had to spend it on either pilot training or ATCO training, I bet the vast majority would go for pilot training.

As an OJTI I don't care what the motivation is that gets someone through the door, as long as they put the work in and make the grade and become a good team member.

As for the wage we pay TATCs nowadays, ImnotanERIC has hit the nail firmly on the head.

However, the above few posts are a bit of thread drift!

[ShyTorque]

I have heard people say that "at least they get a wage, trainee pilots don't."
Well Trainee atcos dont get to fly planes, they get to sit in a boscombe b&b reading the most boring manuals in the world in the hope that one day they can sit in a dingy room at 3 o'clock in the morning talking sh1t and eating crisps.


But trainee ATC'ers also don't have to go in huge debt to qualify to earn a decent wage.