Back in February 2011 I reported in this Blog on a particularly silly state of affairs. Pilots and controllers had got used to a simple rule where ‘each clearance replaces the old’. This means that in a clearance, such as ‘cleared FL 150, 200 or below 20 miles before X’, the constraint ‘below 20 miles before X ‘ would have to be repeated in a subsequent clearance to say, FL120 to remain in force, otherwise it would be automatically cancelled. This was the case until in 2007 amendment 15 to PANS ATM (Doc 4444), which introduced a new twist. ‘New replaces Old’ was still valid, but NOT on clearances involving SIDs and STARs, when the OPPOSITE applied.
This was presumably because controllers were finding it irksome to repeat all the restrictions contained in a Standard Arrival or Departure. To be fair, it is probably true that most standard arrivals DO still require intermediate constraints to be observed as they are often terrain related. But was this a good reason to tear up the rule book? Surely a suitable phrase could have been found to replace a mouthful of level restrictions.
The immediate result of the change was widespread confusion. This may surprise ICAO, but few pilots and controllers take PANS ATM to bed with them. So it was up to individual States to communicate the changes, which they did with typical thoroughness. Result, total confusion in November 2007 when the amendment took effect. London TMA controllers, who typically cancel SID vertical restrictions on practically every departure, were running out of breath and time saying the new formula; some pilots questioned what they were to do, others merely assumed, and only some got it right. The UK CAA made several minor changes recognising that they couldn’t unilaterally turn the clock back for fear of creating even more mayhem. For a few years now, London ATC have been saying ‘Now’ to mean ‘climb and ignore the restriction in the SID’, but that isn’t totally unambiguous. It was clearly up to ICAO to sort out the mess they had created.
Fast forward to 2009 when ICAO first polled States about the difficulties they were experiencing and then accepted an offer from CANSO, the Air Nvigation Service Providers’ trade organisation, to study the problem and provide solutions.
The CANSO ‘HITLS’ report (that’s a ‘Human in the Loop Study’ for these politically correct days) appeared in late August this year. To be polite, it is a disappointment. It doesn’t address the central problem, the inconsistency between SID/STAR level change clearances and all others. What it did was to evaluate just two (2) phrases for climb or descent respecting the previous restrictions, and only one (1) phrase for the opposite case, ignore all previous restrictions. I don’t see how that can be described as a thorough investigation, but I’m not paying the bill.
The report was presented to a recent meeting of the ICAO Air Navigation Commission, and as I was at ICAO for other business I was able to listen to the ensuing discussion. To their credit, the representatives of IFATCA, IATA and IFALPA all noted the central inconsistency in the PANS, but this didn’t deflect the discussion from minute dissection of the phrases suggested. I’ll get to those in a moment, but the point is that IF the inconsistency were removed, either by reversion to the status quo with all new clearances replacing old, or the reverse, all restrictions apply until specifically cancelled, THEN there would be no need for one of the two sets of phrases trialled in the CANSO study. At least half of the problem would then be solved automatically. But instead we were treated to a couple of hours of talk in which no one seemed to notice that half their discussion was irrelevant, and that they had left the glaring inconstancy in the rules.
For clearances which required restrictions for the SID/STAR to be observed, there were two suggestions on offer:
1. Climb/Descend via [SID/STAR name’] [alt/FL]
2. Profile climb/descent [alt/FL]
Supporters of the first said that this was a formula already used in the USA, but many others felt that ‘via’ was habitually used for the horizontal and didn’t sound right for the vertical. Similarly, the latter liked ‘Profile’ because it suggested a series of vertical restrictions, but others didn’t like anything new…. In the background was the feeling that many delegates didn’t like a study that only used native English speakers (and the case for ‘via’ wasn’t helped by its being pronounced variously ‘VEE-AH’, ‘WEE-AH’, and ‘VIE-AH’ during the debate).
As for the ‘ignore all previous restrictions’ clearance, there was only one ‘alternative’ on offer, ‘Open climb/descend’. There were worries that this was a specific phrase used in Airbus flight control and could be misconstrued, though precisely how wasn’t clear.
No decision was taken at the meeting, whose only purpose was to allow CANSO to make its presentation. But some time soon there will have to be a decision. If the discussion last week is any guide, we will be left with two only semi-satisfactory new phrases, one of which is entirely unnecessary, a PANS that retains a deep central inconsistency, and probably more confusion in some hitherto undetected area (because that’s what happens when illogicalities are allowed to survive).
Frankly, you couldn’t make this up, and I quietly despair at the thought of whet new nonsense is still in store for us…