Triangulation: (n.) The calculation of positions and distances using the division of a map or plan into triangles. By extension, the determination of distances and relative positions of points spread over an area.

Hello dear readers, and welcome back to our weekly blog.

This week, I will tell you the story of a lost pilot again, but since I know that you have already learnt that ATC was the best ally when trying to recover from a loss of situational awareness in one of our former articles, I will address this piece a little bit more towards how to proceed when disorientated, and also how controllers can help.

So, I was working an evening shift, and traffic was low, we only had a couple of general aviation aircraft flying around, as the weather was fair. As often, many of those flights were just hanging around the control zone and did not venture too far away, and most of them were under constant radar surveillance, even though they were outside controlled airspace.

As dusk approached, several of these aircraft came back to land, actually, most of them. Only a few remained outside for a while longer, so after a small increase of traffic, I contemplated the list of active flight plans I still had active and tried to locate them around on the radar screen.

You may know it or not, but, when you are flying to a controlled aerodrome, the controller is responsible for making sure that you land safely, and for closing your flight plan accordingly. And when I say ‘flight plan’, I do not mean only the ones that were filed manually on an ICAO flight plan form, by Internet or through a flight planning APP. I mean all flight plans, including the ones that the controllers create for you, and which are called APL, for abbreviated flight plan.

Indeed, each time you ask for the services of an ATS unit, for example to depart from or land at a controlled aerodrome, or even just to cross a piece of controlled airspace, the sole fact of calling up ATC, giving your flight information (callsign, flight rules, ADEP, ADES…) is de facto tantamount to filing a flight plan. The controller takes down your information, and issues a clearance based on it. An APL is actually mandatory to obtain such a clearance.

Well, as I said before, when receiving an APL, a controller becomes automatically responsible for verifying that you reach the end of your intended flight path safely. And that includes closing your flight plan if you land at their aerodrome. (Don’t forget that if you land at an uncontrolled aerodrome, you must close your flight plan yourself.)

So, here we were, on a beautiful evening, I was busy shortlisting the aircraft that were still due to land at the aerodrome where I was working when, coincidentally, one of them called me.

ACFT: “Tower, huh… this is G-ABCD, I am lost, I am not sure of my position, can you help me to come back to the airfield?”

TWR: ”G-ABCD, Tower, affirm. QDM 090.”

Of course, a QDM is our go-to solution, as it is very easy to obtain (yes, it is fully automated), and it certainly is very useful for the pilot, who simply needs to fly that track all the way to the airport. This being said, back in the day, it lacked a major piece of information: the distance at which the aircraft was. We could have a ballpark figure for the maximum distance at which the aircraft could be, by a quick calculation of the range of its VHF signal, based on its height, but the fact is that the aircraft could be literally anywhere between the aerodrome and that maximum distance. (Nowadays, we are able to receive QDMs from several stations simultaneously, making it possible to triangulate and pinpoint an estimated position.)

My next question was therefore to ask the pilot if they had a transponder, and if so, which code they were squawking.

TWR: ”G-ABCD, advise transponder capability and confirm squawk”

ACFT: “Transponder mode A/C, squawking 6317, G-ABCD”

I looked around the CTR and beyond, and I couldn’t find that code on the screen, so I widened the range of my screen, and still saw the aircraft nowhere. Although we were in a relatively flat country, It occurred to me that they may be flying too low to be picked up by the radar beam, especially if they were far, so I announced it to the pilot and asked for more information:

TWR: “G-ABCD, negative radar contact. You may be below coverage, I suggest you to climb, and report what you see on the ground, I will try to help.”

ACFT: “Huh, roger sir, we climb to 3000 feet, and I see a highway, and right of it there is a lake and a forest.”

All right, my beautiful attempt to demonstrate my knowledge of the local geography failed miserably there, as we were in an area filled with motorways, lakes and forests, and what looks like a motorway more that another motorway?

I then tried enlisting the help of my colleagues at the Flight Information Center, when my phone rang. It was the tower of another aerodrome about 50 miles to the West.

TWR2: “Hi, the aircraft squawking 6317 about 20 miles west of our aerodrome, 2600 feet and climbing, is it one of yours?”

Me: “Hey, yes! The guy is lost, I gave him a QDM, but I was still searching for him”

TWR2: “Yeah, he is in my TMA, could you pass him on my frequency as soon as you can? I have traffic there”

Me: “Oh, sorry, mate, I genuinely had no idea he was there”

TWR2: “No worry at all”

So, I dutifully transferred the pilot to my colleague’s frequency, and widened my radar view as far out as I could. I found my traffic, 75 NM west of the airport, while he had initially told me he would stay in the area…

Fortunately, the occurrence did not cause any trouble, and except a safety report, nothing else had to be done. But there were a few things I did learn from this event, and this what I would like you to take home after you finish reading this:

  • As a pilot, try to make a quick assessment of how far you COULD be from the aerodrome where you are calling. For example, if you fly at 60 knots, it means 1 NM per minute, so if you have been airborne for an hour, you are within a 60 NM radius. 90 knots is 1,5NM per minute, 120, 2NM, etc…
  • Try to keep track of the last known position before you got lost, when and where it was, and in which direction you have been flying since then. These are very useful pieces of information for anybody trying to help you out.
  • Call for help as soon as possible, that will help you to avoid any infringement in another piece of controlled airspace.

Now, this should help pilots staying safe, but I would like also my fellow air traffic controllers to benefit from my experience:

  • If a traffic calls you while lost and without a single clue of their current position, ask them if they have a transponder, make them squawk and if you do not find them, ask for an actual time of departure, the general direction of the flight since take-off and if they know, a last know position and time. Still, do not take that information for certain, and do not assume anything
  • Do not issue directional or vertical movement instructions to avoid sending the aircraft into another airspace
  • Enlist the help of FIC, as well as the neighbouring aerodromes before trying to direct the aircraft to you.

It was a safe and happy end, and the pilot was very, very thankful to come back home at the end of the day, but to everybody out there, please never take safety for granted, never assume and always get help from all sources available.

That is also valid in our current health crisis predicament, my friends. Stay safe and healthy, and until next week!