Level busts - quantity / order of ATC instructions

[Butter side-up]

Hi

The subject of level busts is never far away from any of us. We have recently been discussing it at our company and considering how mistakes can happen.

One area that I have always thought was a POTENTIAL cause for problems is the quantity and order of ATC instructions that are given in a single transmission.

For those of you controlling us, is there any limit on how many instructions can be given at one?

"Jersey 345, turn right heading 080 degrees, climb flight level 70,speed maximum 250 Kts. Contact solent radar 120.225" Is this seen as a goog amount of information to transmit in one package?

What about if you are descending an aircraft to it's first altitude and so need to transmit the local QNH?

Is there any written guidance on this, or is it down to professional judgement on your part?

Secondly, is there any prescribed order that instructions should be braodcast in? This may sound like an odd query, but I know that my company tells us to set the cleared level in the autopilot before setiing any heading / direct to or speed clearances. This is because level busts are rightly seen as so dangerous. However, since receiving this advice I have noticed that "laterlal" clearances are always given before "vertical clearances". As I said earlier, I have been wondering whether this order is in accordance with some ATC regulations or merely custom.

Any comments on this gratefully received.

All the best.

[Lifes2good]

Messages should not contain more than three specific phrases comprising a
clearance, instruction or pertinent information. In cases of doubt, e.g. a foreign pilot having difficulty with the English language or an inexperienced pilot unsure of the procedures, the number of items should be reduced and if necessary passed, and acknowledged, singly.
This is an extract from the CAP 493 Manual of Air Traffic Services part 1. Not always easy to do when really busy but hope this helps.

[Butter side-up]

Thanks for that - I have downloaded the relevant document.

Any thoughts on the order with which multiple instructions are given?

All the best.

[radar707]

And a frequency change instruction should never be issued with any other instruction that requires a readback

[chevvron]

I was always taught (confirmed on my TRM course) NEVER to pass more than 7 numbers in one instruction.

[Butter side-up]

Radar707

Is this written down in CAP 493? - I could not find a reference to it.

Thanks in advance.

[Northerner]

"Any thoughts on the order with which multiple instructions are given?"


Not really, except that any that are for legal or separation purposes would come first, any that then give best service to the aircraft involved, or my plan (:E ) come later.

Other replies good, particularly from Radar 707, we should never give a frequency change with anything else that requires a mandatory readback.

Cheers,
N

"Keep smiling, it makes people wonder what you're up to..."

[spekesoftly]

Regarding the order of items in an ATC transmission, I normally try to give information first, and instructions last:-

"C/S vectoring for the ILS R/W 27 information Bravo, fly heading 060 degrees, descend to Altitude 4000 feet QNH 997mb"

Hopefully it helps make the mandatory read back a bit easier, but interested to hear pilots' opinions and preferences.

During very busy periods, I may transmit just the turn and level instruction, and follow up with the 'information' in another transmission, on an opportunity basis.

[mad_jock]

Just a personal opinion.

Thats 4 manditory readback items. RWY, Heading, alt and QNH

And involves two changes to flight path and an altimeter change with its associated cross checks.

At that stage of the proccedings (below FL100) the paper work is away so the PNF has to remember it all.

Personally i find it easier if you seperated the changes in flight path, heading changes from the level changes then it's easier for the PNF to cross check the PF has set the correct values.

You will proberly find that the read back is more snappy as well so the total time for 2 sets of instructions with 2 readbacks is less than the 1 with full read back, with the bonus of less mistakes or "say again"

[JustaFew]

Although passing information and then instructions is a better way, saying too much can overload pilots. I would reduce what spekesoftly says to the instructions first, wait for the correct readback, give the pilots a few seconds
to carry out said instructions, and then pass information.

[DirtyPierre]

"C/S vectoring for the ILS R/W 27 information Bravo, fly heading 060 degrees, descend to Altitude 4000 feet QNH 997mb"
Hmmmm....must agree that this is a lot of information in one transmission. Given that any incorrect readback needs to be corrected anyway, wouldn't it be better to reduce the chance of an error and break this example into two transmissions.

For example:

ATC: "Qantas 26, Glenn 2 arrival, Blaka transition, maintain F350"
ACFT: "Qantas 26, Glenn 2 arrival, Blaka transition, maintain F350"
ATC: "Qantas 26, for sequencing, cross Blaka at time 26 at 250 knots"
ACFT: "Qantas 26, Blaka at 26, 250 knots."

Seems that a little more air time taken up with transmissions, but more likely to get the correct readback.


BTW, do you still say millibars in the UK? Hasn't it been hectopascals for some time. And why do you say millibars when giving QNH? Surely it's a lot different to giving it in inches to our recalcitrant american friends who know nothing of the metric system.

[ukatco_535]

I was taught in the military when flying and in ATC, give the most important piece of info last - it sticks in the mind that way.

i.e. "Squawk 3730, Flight information Service, QNH 1012"

And never more than three bits of info at once, with something to break up the numbers, as in the above example.

Seemingly it's a human factors thing.

[BALIX]

BTW, do you still say millibars in the UK? Hasn't it been hectopascals for some time. And why do you say millibars when giving QNH? Surely it's a lot different to giving it in inches to our recalcitrant american friends who know nothing of the metric system

Yup, we still say millibars. It is one of several 'opt outs' from the ICAO standards that we have. I don't know why, but then again I don't know why they changed to hectopascals in the first place. It was a change that achieved absolutely nothing as far as I can see.

[5milesbaby]

butter side up, CAP 493 appendix E page 10, 6.2:-

Transfer of communication instructions should be passed in a single message. Items which require a readback should not precede the frequency or channel change instruction.

[radar707]

5miles u beat me to it.

As for saying millibars when passing QNH / QFE below 1000 I seem to remember that it came about because when we weren't saying it some of our American cousins got confused and would set 2992 instead of 992 etc. and this was introduced to reduce the chance of a level bust occurring

[zzjayca]

Surely it's a lot different to giving it in inches to our recalcitrant american friends who know nothing of the metric system.
We use inches of mercury for altimeter settings in Canada as well, and we know the metric system.

[Right Way Up]

At Lgw quite often you get "ABC 1234 turn left heading 270 descend altitude 4000 QNH 995" followed immediately by "ABC 1234 contact LGW approach 126.82". As soon as we get cleared to an altitude there is a set routine of selecting new altitude, setting the QNH, and crosschecking this. This frequency change often disturbs this routine with the risk of serious consequences. UK ATC still the best in the world imho.:ok:

[danceswithsheep]

Right way,
You know the best way of letting us on the ground monkeys understand better what happens in a cockpit? Fam flights. I am an instructor at a centre and think I would be able to pass on better knowledge and provide a better service if I know more about what and when you are doing things.
This kind of forum provides some idea but face to face is always better. We have recently done TRM courses and it made me at least realise the team is the unit, surrounding units and the aircraft all to acceive a goal. Push for fam flights and centre/airfield visits.
Thats me off the soap box for about an hour!!!!!!!!!!!!

[thelorenzo]

"Any thoughts on the order with which multiple instructions are given?"
Not really, except that any that are for legal or separation purposes would come first, any that then give best service to the aircraft involved, or my plan (:E ) come later.

NavCan MANOPS are quite specific about order:
412.1 Issue clearance items, as appropriate, in the following order:
A. Prefix
B. Aircraft Identification
C. Clearance limit.
D. SID
E. Route.
F. Altitude.
G. Mach-number.
H. Departure, en route, approach, or holding instructions.
I. Special instructions or information.
J. Traffic information.

412.1 Note: It is important that an IFR clearance contain positive and concise data phrased in a consistent manner. This is especially true of a clearance that will be relayed through a communication agency, since the clearance must be relayed verbatim.

So, yes, route before altitude.

the "as appropriate" in the manop does give us some room to maneuvre within the rule. Any unnecessary items are omitted, and sometimes they are rearranged slightly.

For example, "abc 123, maintain FL 330 Through fl 320, cleared direct yzz flight planned route" can't really give him the "through fl 320" if he hasn't been cleared past 310 yet.
Item I, special information, is often bumped to the front as well, or sent in a separate transmission.

[Butter side-up]

Is there any reference for the order of altitude / heading / speed / frquency change instructions in the UK rules?

Thanks

[DirtyPierre]

We use inches of mercury for altimeter settings in Canada as well, and we know the metric systemWhich begs the question - why aren't you using the metric system?

[Right Way Up]

Danceswithsheep,
Could not agree more with you on that one. I cannot remember the last ATCer I took on the jumpseat. A great shame! However I will try to do an ATC visit this spring.

[Scott Voigt]

I wish that we could even do them over here <sigh>...
Scott

[Three Blades]

I have a further question:

Do you reduce the amount of information you provide in one go if you know it is a single pilot helicopter that you are speaking to ?

My question is not because I think that heli pilots have lower cognitive functions ;) than plank drivers but because we tend to have both hands full most of the time :ooh: ! and are less likely to be able to take the instruction down in writing.

[Jerricho]

Is there any reference for the order of altitude / heading / speed / frquency change instructions in the UK rules?
Thanks

Not a reference, but a very wise instructor once said to me when issuing a heading and a climb/descent in the same transmission, always issue the heading first. That way the aircraft will be pointing where you want it, should the second half of your transmission be cut off..........which made total sense to me.