Writing in the sky

On 11 July 2019 I took the RV up to draw something in the sky.

My conscience got the better of me and I thought I should begin with something that wouldn’t get me in any kind of trouble.

The 2019 Air Tattoo was just around the corner and to generate a little extra exposure online I decided to try and write the words ‘RIAT’ in the sky above the Cotswolds.

My first port-of-call was a friend from NATS called Em who works in the communications team. We’ve all seen their graphics depicting airspace infringements and ‘busy days’ in the UK’s skies so I pitched the idea of them tracking two bandits in an RV-6.

Fortunately, NATS has a large presence at the Air Tattoo (not least their volunteer controllers who man the tower all week) and also have a big STEM engagement area in the Techno Zoneยฎ. Thanks to Em, they were more than up for the idea.

Planning

My primary concern was that we operate a Mode S but non-ADS-B transponder, so the exact GPS position isn’t broadcast which would have led to patchy coverage in the event of the signal not being continuously received. However, I was talking to our nation’s main air navigation service provider. They have radar!

Em at NATS informed me that broadcasting Mode S would be adequate, as they could also track using primary radar. I decided to fly the route at 4,000ft to give as clear a picture as possible to both primary and secondary radar systems.

Another reason for flying at 4,000 was that I’d be above Brize Norton’s CTR and therefore not have to worry about getting a zone transit and the added stress of ‘communicate’ among the other two vital pillars of safe flying, ‘aviate’ and ‘navigate’.

To plan the route I used the computer based version of SkyDemon as it allows much more accurate placing of waypoints and measuring of straight lines. Doing the same on a phone is a bit tricky as you end up fumbling around with your fingers if you place a waypoint slightly off.

Once the route was drawn I needed to decide the best way to fly it. The letters R, I and T were straight forward but the letter A presented me with a few options. I decided on the path below which allowed for one repeated section along the A.

The Flying

This flight was, like every flight, a learning experience and really not quite what I expected. You have to aviate and navigate constantly, checking every few seconds that you’re on the purple line and turning at a correct rate (for the curved bulge on the R).

What surprised me most was how disorientating it can be. You can’t really use fixed landmarks on the horizon as you would when navigating on a cross country flight. As you can see in the video and my raw trace there were a few ‘adjustments’ made where we rolled out only for SkyDemon to refresh a second or two later and show us 5 or 10 degrees off heading.

Another cause of the disorientation was the angles of bank and G. My father flew the letter i and did a quick reverse turn (sharp right then left) at it’s peak, pulling almost 3G in the process, which is made worse when you are head down in the cockpit watching the laggy map refresh every half second!

As you can see from the long video above, some of my turns onto a heading did require adjustment but the basic idea worked. I edited the transponder ID to the default ‘NOREG’, which is visible when the aircraft registration is left blank. This was for less conspicuity (in the sense of any public watching, rather than from an aviation perspective).

From a ‘communicate’ perspective we spoke to Brize Norton Zone to say we would be flying 500ft over the top of their CTR and they were happy for us to continue on without any kind of service. The only other aircraft we saw during the whole flight was a blurry looking 658 Sqn Army Air Corps Dauphin heading to Herefordshire… We actually raced them line abreast at about one mile spacing as we descended down from 4,000 onto finals.

Elsewhere, NATS’ own developer was tracking us though their Airspace Explorer app (which the above video is produced from). They used the raw data to create the final short video at the bottom of the page.

On the ground

I had a message from a friend within 5 minutes of landing of a FlightRadar24 screenshot and the words, “Was this you?”.

This was followed by another one and eventually I saw the following on Facebook.

That shows the effect of not having ADS-B out. The R is quite clearly defined (perhaps I am close to a number of receiver stations in the Cheltenham / Gloucester area), but the quality of the route is clearly poor on the A and T.

Soon after this BFBS Brize Norton had picked up on it and a couple of days later I was interviewed for their show to talk about how I planned and flew the flight.

One thing to remember when watching the video below is that it is viewed from a slant angle. Where I did correctly fly the cross of the T, it looks inaccurate here because I descended towards the end.

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