Conundrum [n, -s]: A confusing and difficult problem or question.
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I would like to talk to you about a very particular problem today. One of the sentences that is most often heard in flight decks (one day, I solemnly promise I’ll find out and explain where the word “cockpit” comes from, far from poultry or other considerations):
“What the hell did he mean by that?” – and that would be without using the push-to-talk.
We You have all been there, I suppose. You are taxiing at an appropriate speed (before departure: less than 15 knots GS – after landing: flash-what-the-hell-let’s-call-it-a-day knots GS) with an A5 chart on your knees that has the consistency of a “Value” single-sheet napkin from a fast-food restaurant, and probably with a big smudge of engine oil on the taxiway where you are.
It’s dark out.
The flood light inside your aircraft hardly floods anything, but you can see the shadow of your own head magnificently clearly on the chart.
Aaand… here we go:
taxiways
The pilot has been instructed to taxi to the holding point of RWY 07, and did a correct read-back. After the holding point, the taxiway splits into N1 that allows a backtrack and full-length departure and N2, which makes a 150°-turn onto the runway for a faster move.
Upon approaching the holding point (the quadruple yellow line painted on the ground), the pilot sees a sign saying “N”. The aircraft is really heavy tonight, and a full-length departure is really necessary.
Pilot: “Huuuuuh… Tower, can you confirm that we can go to holding point November 1?”
Controller: ”Affirm sir, expect departure from Intersection November 1, but hold short RWY 07, I have traffic on final, company 737, 4 miles from touchdown”
Pilot: ”Ah, roger, thank you, sir”
And that is where, in spite of their colleague hurling down final approach, both pilots happily continue taxi past the holding point.
Controller: ”I confirm, hold short of runway 07, company 737 on final”
Pilot: ”Affirm sir, we have the traffic in sight”
Do you see it coming? Hold on to your hats…
Controller: ”Do you confirm you are on the runway now?”
Pilot: ”Huh… affirm sir”
Controller (to the aircraft on final): “Go around, I say again go around, traffic on the runway”
And that, my friends, is a splendid, state-of-the-art runway incursion: “Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take-off of aircraft.” (ICAO Doc 4444 – PANS-ATM)
Now, let’s go back to our story and see what happened:
The airport signage can be considered ambiguous. The pilot was genuinely convinced there was a second holding point further for the intersection that he wanted, so he continued taxiing until seeing it, disregarding the proximity of the runway;
The controller was ambiguous in his response to the pilot’s request to continue to N1. Yes, they could continue taxi, and No, they had to hold short. In doubt, the pilot should have asked for clarification. But then again, there was no doubt in his mind. One could possibly wonder if the controller was aware of the position/intentions of the taxiing aircraft, and also about the questionable signage;
The pilot did not interpret the chart correctly: holding points are depicted on aerodrome charts, and it should have been clear that by crossing the painted lines, he was de facto entering the runway where someone else had been cleared to land.
Fortunately, the controller regained situational awareness quickly and was able to keep control of the situation by issuing avoidance instructions, thereby averting a more serious incident, BUT we can learn from that:
- that whenever there’s the tiniest question mark anywhere, both pilots and controllers MUST clarify. No matter what time it is, what weather conditions are, how heavy the workload is;
- that controllers must know their aerodrome like the back of their hand, in detail. If anything can be misunderstood or even misinterpreted, controllers must be aware that such misunderstandings are bound to happen and that they should pay extra attention;
- that pilots should make sure that they can follow ATC instructions safely beyond any doubt, and that if something just feels even a tiny bit strange, that one last confirmation never hurts (In this case, the pilot could have asked, even in plain language, something like “And you confirm that we can cross this first holding point” to alert the controller to the pending manoeuvre)
- that both pilots and controllers must realize that a control tower is always far from some parts of the aerodrome. The greater the distance, the bigger the risk of parallax effect which may prevent a controller from having a visual confirmation of a given traffic situation, or that could even create a false image in the controller’s mind. This is particularly the case when looking in the distance, where a taxiway is parallel with the runway.
As I often say to students, pilots and controllers are part of one single team, even if they are physically far apart. Trust each other as much as you can, and question each other as much as you need. Nothing bad will ever come out of that.
Ok. So, until next week, my friends. Fly safe and speak well.
