R/T ambiguity question
 

Some time ago, out of London area climbing to FL 260 (?) dct KOK, upon first contact with Maastricht at about FL 220: "xyz nnn g'morning, after KOK dct BOMBI(,) climb FL 350." Verbatim readback with selection of FL350 on flightdeck. After some time and ensuing small talk at FL250 we decided to seek immediate clarification wheather KOK had been a condition to climb clearance or not. It had not been, everybody happy, SRM applied (separation resource mngmt :D ).

Now, my question to you ATC partners: was the instruction potentialy misleading or was it by the book only we failed to recognize? What would be the proper and foolproof (receiver-wise) way to give a conditional or non-conditional instruction in this example? I can indeed imagine "clb FL 350 dct KOK BOMBI next", still I am interested in your views, in particular for the conditonal case.

Thank you,
FD.

Can see how the instruction may have been confusing. I think it was technically correct though, firstly it is very unusual in a radar environment to be given any kind of conditional climb and it is wholly frowned upon. If somebody had decided to do it I would expect a more explicit instruction such as "route KOK, BOMBI, after BOMBI climb FL350". As in any situation when you are not sure, you did the correct thing, seek clarification.

The amibiguity could have easily been solved by the use of '....climb now FL350....'

If there was a restriction on the climb I would :
a) not issue the climb clerance, or
b) mention "after KOK" or "after Bambi" , and
c) carefully listen to the read back and make sure the restriction was well understood.

As for Gonzo's suggestion, I only use "climb now", "descend now" or even "turn ... now", enphasizing the word "now" when I an immediate response.




A/C departs, makes first R/T contact with Approach.
ATC replies "Climb to FL 240. Identified"
- Radar Identification is a fact when the "Identified" is pronuonced ... Same sentence but two diferent clearances/information. ;)

I must admit i can't really see the ambiguity. They are esentially 2 separate phrases.

"after koksi dct bambi. climb FL350" and restriction would have to be specified very specifically

and agree that "now" should only be used to emphasise a slightly more urgent situation (but not one that requires use of "expedite climb"etc) or one where for example an aircraft was initially given "descend when ready FL210" and one changes ones mind (for whatever reason) to "descend NOW FL 210"

Think you need some radar experience Gonz :ok: :ok:

Of course, I couldn't begin to start preaching to those who work Nottingham East Midlands Robin Hood Tees Valley radar, :E , but from a pilot's point of view I would think that if you didn't want me to do something now, you'd say 'pilot's discrection'. From a safety point of view, there can only be two time frames, do it (now) or do it when you want to (pilot's disctrection, when ready etc). There should be no grey area.

In the case quoted, the use of the word 'now' would have removed any ambiguity. The same result would have been achieved by putting the climb clearance first.

Trouble with that is that "at your discretion" only tends to be used when you aren't preapared or qualified to clear someone to do something

eg an AFISO "...land at your discretion"

at EMA we don't clear the Helimed to lift from the pad as its off the manoevering area and we can't therefore KNOW its clear to do so ergo "...lift at your discretion"

Similarly, an aircraft, clear of CAS, not recieving a radar service requests descent .."G-CD nothing known to affect, descend at your discretion"

To use it in an airways environment IMHO would be a little strange and would I think unsettle the crews a little for the reasons given above......discuss

Domestic flight.
Flying in controlled airspace.
Destination is a controlled aerodrome.

"ABC123, pilot's discretion descend to FL 80."

;)

ambiguity
 

to me it seems extremely misleading.
"After" should be a key word . when you give an instruction to climb without really specifying when or where , the place in a sentence can lead to a very dangerous situation.
how many incidents have we seen that was due to bad R/T

Having done a straw poll at work all agreed that the example given was very ambiguous and that the pilot was right to question it. The solution would be either to start the transmission with "ABC Climb FL350, from KOK track direct BOMBI", or break it up into two separate transmissions, or reitterate the whole clearance, ie. "ABC cleared present position KOK direct BOMBI, Climb FL350." As there is no mention of "after" there is no confusion as to when to climb.

Certainly in agreeance that saying ABC after KOK track direct BOMBI climb FL350, does leave it open to interpretation as to whether you mean climb now, or after KOK. Poor phraseology, very poor.

I agree with ANSA and FD was right to question.

Even if the phraseology is book perfect, any misunderstanding or perceived ambiguity should be questioned.

This was definitely an ambiguous transmission.

cheers

VL

If anyone, anywhere, in the loop is doubtful it should always be queried - remember Tenerife.

The reason the clearance was given this way possibly relates to the way the system works at Maastricht. On initial contact with a sector the flight is assumed. Amongst other triggered actions this can briefly display the route of the flight through the Maastricht airspace. As this is only displyed for some seconds the route - direct where possible - tends to be given first.

I agree the confusion could be avoided by using the phrase, "Continue climb" or "Climb now".

Lon More, here since before Pontius was a Pilot or Mortus a Rigger

Not misleading in my book from an area point of view. Never used a clearance to climb at a particular point. May say leave xxxxx heading 123 but thats about it.

I tend to leave the important part of the transmission to the end as some pilots are all too keen to jump in with climb or descent without hearing the rest or are more likely to forget the first bit if the less important said second.

This leads to crossed transmissions and any routeing may have been to aid but not prove seperation against other a/c and is therefore useful for you to follow.

It may not be ambiguous for you Bwatch but just because you have never issued a clearance to climb at a point, it doesn't mean that other controllers haven't issued such a clearance, and more to the point it doesn't mean that pilot hasn't previously recieved such a clearance. There is a possibillity of confusion on the part of the pilot and as such the pilot was right to question the clearance. Preferably the controller should have either cleared the aircraft to climb first, and then on recieving that readback, give the direct tracking clearance. In a procedural environment it is common to clear an aircraft once past a point that is known to be clear of a procedural area of lateral conflict with another track, to climb after that point. It is a common practice and is completely legal, and as such, a clearance of track direct to a point and climb, is poor phraseology.