Video: Diversion aversion

Return edit.00_08_21_05

Alastair looking anxious

Dodging a moderate rain shower when you’re flying is usually no big deal.  But when the shower is parked right on your route, and there’s restricted airspace to your left, right and below you, and controlled airspace above you, things can get a little tricky.  This was the scenario faced during my return flight from Gloucestershire to Biggin Hill.

Scroll down for the video

Earlier in the day, Alastair and I had flown from Biggin Hill to Gloucestershire.   I was expecting our return trip to be easier, since the weather forecast suggested things would improve by the afternoon.  Alas, the forecast had been amended during our outbound leg, to show that rain showers were now more likely.  We would have to avoid the showers, because the freezing level (the point at which airframe icing forms) was only 1500ft or so.  I knew I could divert or turn back if I got stuck, however in practice, diverting – at least, the old fashioned way – is no easy task.  Plotting and then flying a diversion in the air was the task I found most difficult during my PPL training – I famously called my instructor a b***ard when he first made me do it!  You can see me plot a simple diversion on the outbound flight, if you haven’t seen this already.

India Zulu's cockpit

India Zulu’s cockpit

India zulu isn’t equipped with a certified GPS, and the ADF (Automatic Direction Finding receiver), which tracks non directional beacons was removed and never replaced.  The route I flew on this trip, didn’t lend itself to VOR (VHF omnidirectional Range transmitter) tracking, primarily because the CPT VOR was out of service for maintenance.  This lack of radio navigation equipment, and the complicated airspace around south east England makes navigating quite difficult.  You really have to study your chart well, fly accurate headings, and keep a keen lookout for landmarks along your route.  When you need to divert from your intended route in this area, you are faced with a myriad of gliding sites, military zones, parachute dropzones, restricted airspace, danger areas, high intensity radio transmitter zones, etc etc.  All of which would probably be ok, if you didn’t also have to constrain yourself to a narrow vertical band of airspace because of the complicated Class A LTMA above (London Terminal Manoeuvring Area).  This is out of bounds to your average PPL.

SkyDemon map

SkyDemon map

Diversion aversion!

On this flight, in spite of my aversion to diversions, you’ll see that I was constantly keeping a re-route in mind each time we faced a rain bearing cloud.  My language did turn blue at the prospect though!  We managed quite well until hitting a very large shower to the west of Reading.  There was absolutely no way we could fly through it.  Our wings, pitot/static tube, windows and prop would have iced over in a heartbeat, and the visibility would have put us into Instrument Meteorological Conditions (IMC).  I decided to see if I could skirt around it, knowing that I had an escape route back north west if I needed it.  But I had to weave between/above two restricted zones which stretched from the surface to 2400ft, and class A controlled airspace to the east, which spanned from 2500 above.

rainWe made it through, as you’ll see in the video below.  I film my flights, not only to share my journeys with you, but also to review myself with the aim of becoming a better pilot.  Looking back, there were several lessons to be learned from this flight.

Firstly, I need to watch for the press-on-itis – a common pilot affliction.  On this flight, I pressed on towards a nasty shower, knowing full well that it was going to be a problem.  I think I somehow thought in my mind it would magically move out of my way before I got there!  Perhaps it would have been better to have planned that diversion afterall – avoiding all that complicated airspace in the process.

Secondly, that shower was quite developed.  While not a typical cumulonimbus in my estimation (avoided by pilots at all costs), it certainly had some of the characteristics of one, and on reflection I wonder if I should have given it more respect, and a bigger margin.  Ultimately, this would have meant making a considerable diversion.

I’d be interested in your views on this, so please feel free to comment below.


Link: What type of cloud is it?

Here is a good guide to clouds from the UK Met Office

The relevant aerodrome weather forecasts for the day

Brakes off EGBJ 12.50, Brakes on EGKB 14.20.  The shower was to the north of Blackbushe aerodrome.


TAF EGLF 230723Z 2307/2315 28005KT 9999 FEW040=
TAF EGLF 230804Z 2309/2318 28005KT 9999 SCT040 PROB30 TEMPO 2309/2312 8000 -SHRA=
TAF EGLF 231101Z 2312/2321 32006KT 9999 SCT025 PROB30 TEMPO 2312/2314 8000 -SHRA=
TAF EGLF 231356Z 2315/2322 34006KT 9999 SCT030=

Brize Norton

TAF EGVN 230745Z 2309/2409 31007KT 9999 FEW040 PROB30 TEMPO 2309/2313 SCT016=
TAF EGVN 231037Z 2312/2412 33007KT 9999 SCT045 PROB30 TEMPO 2312/2313 SCT018=
TAF EGVN 231341Z 2315/2415 36007KT 9999 SCT040=


TAF EGLL 231052Z 2312/2418 33008KT 9999 SCT040 PROB30 2404/2409 6000=

Video: Gloucestershire to Biggin Hill VFR