Category: Navigation – PPL

Calculating cross wind and headwind

Posted on November 17, 2025 by - IMC rating, Navigation - PPL, Tips

We need to calculate or estimate cross winds for several reasons

  1. To check whether the cross wind is within limits for take-off and landing
  2. To calculate wind drift (the difference between heading and track) on a cross-country flight
  3. To estimate wind drift for an unplanned diversion
  4. To calculate wind drift / heading correction on an instrument approach

There are several ways we can go about this this.

    • For a cross country flight, calculate the required heading (and implicitly the drift) before flight using our trusty CRP-1 (Whizz wheel) or with a planning app like SkyDemon, or with a wind protractor.
    • Use an app like Windstar to calculate headwind / tailwind, cross wind and cross wind drift, so we have the info ready to use when needed
    • Use a graphical calculator, on the fly, like the one which I present on my VFR reference card
    • Calculate the maximum cross wind drift using this formula: Drift = wind speed x 60 / TAS
TAS –> 60 kt 90 kt 100 kt 120 kt 
Max drift 1x 2/3 x 3/5 x 1/2 x
Wind speed in kt
  • And then estimate the actual drift, on the fly, using a simple rule of thumb
Roughly, ‘nothing, half, all’ rule wind 30o off, cross wind = ½ x wind speed and drift is ½ x max drift;

wind 60 o off, x-wind = full wind and drift = max drift
More precisely, ‘rule of sixths’  Take one sixth of the drift or wind

for every 10o the wind is different to the runway or track direction.

And finally, how do we record the information we’ve derived? We could

  • mark the wind and max drift on the chart and do the rest in our heads
  • look at the app
  • put the info on a paper windstar and paper-clip it to the chart
  • write the info on the instrument approach plate (thanks to one of my students for inventing this!)

 

A VFR kneeboard reference card

Posted on February 9, 2024 by - Flight Performance and Planning - PPL, Navigation - PPL, Planning tools, Tips

As part of my teaching toolkit, I offer PPL students a VFR reference card which fits on the kneeboard. A few people have expressed interest in it, so I am posting a copy here. Other handy planning aids can be found here and downloaded from here.

One side is for Planning with, for example, a checklist of items to be checked prior to a cross-country flight, the CAA take-off and landing performance factors, some Meteo rules of thumb and common conversion factors.

The other side is an In-flight aide memoire, with handy reminders of VOR intercept techniques, the standard closing angle for regaining track, checklist mnemonics, descent planner and a cross wind / drift estimator.

It’s written for a 90 kt training aeroplane, so will serve well for a Cessna 152 and PA28 Warrior. The original form is customisable for other aircraft speeds through an inbuilt spreadsheet.

Do I have to use the whizz wheel?

Posted on September 28, 2022 by - Flight Performance and Planning - PPL, Navigation - PPL, Test, Tips

First a confession. I am a big fan of the flight navigation (dead reckoning) computer, a.k.a. the whizz wheel. Sure, it takes a little investment to learn how to use it, but once over that hurdle, it is fast and accurate.

A bit of history

The ‘flight computer’ was invented in the 1930’s by Lt. Philip Dalton, a US military scientist and US Naval Reserve Pilot. It was portable and intuitive. “Really?”, I hear you say! In those days. slide rules were how mathematical and engineering calculations were performed. They were adopted by the US and UK military and soon made their way into civilian aviation too.

And in the 21st century?

In this digital age, virtually every PPL holder uses app’s on their smartphone for weather, navigation planning and maybe even for weight and balance. So is there an alternative to the whizz wheel in those pesky theory exams? Well yes there is.

An app (and there are many of them!) on a phone or tablet is not acceptable to the UK CAA– the concern here is that it is also a communication device and may hold other apps with which a candidate might cheat.

However, the UK CAA’s exam instructions state that a candidate may use: a “Scientific calculator, or a mechanical navigation slide rule (DR calculator), or an electronic flight computer”. Electronic flight computers were all the rage 20-30 years ago and Sporty’s E6B and ASA’s CX3 are still available, if you have £100 to £150 to spare.

Save your cash

Here’s the solution which several flying schools offer…. Buy Sportys E6B app for your phone and practice with that. It will cost under $10 on Android and a bit more if you insist on using an iPhone or iPad. For the real exam, borrow a Sporty’s E6B electronic computer from your friendly and helpful instructor. The user interface is well-nigh identical. Job done!

2025 edit –  the CAA have now decided that electronic flight computers , in any form, may NOT be used for theory exams. You may still use them in the skills test, but expect to be tested on how they work and alternative manual calculations!

Who’s got the best chart?

Posted on July 31, 2019 by - Navigation - PPL, Tips

Having been flying around Western Europe recently, I’d like to share some observations about different presentations of the ‘standard’ ICAO chart.

Some obvious differences:

  • Controlled airspace is depicted in different colours in different countries
  • French and German airspace is much simpler than UK airspace – none of those complicated slivers of airspace which we have in the UK, with poor altitude notation which just beg to be infringed.
  • German charts fold out east-west in panels about A5 size. So if you are travelling north – south, you need lots of charts
  • French charts are bigger and generally on flimsy (but easily folded) paper.
  • Our laminated UK charts are huge and require pre-folding before getting in the cockpit!

Personally, I find the French and German charts much easier to read than our UK charts.

Some less obvious differences:

  • French charts do not show VRP’s around airfields – you need to look at the airfield plates in the AIP for these – or use SkyDemon
  • French and German charts show the frequency to use for a Flight Information Service (our UK charts do not), and the sector boundaries for the frequency. And that frequency is typically also the one to use for a class D clearance, so the RT can be seamless. The font and lines are green in France and blue in Germany, and depicted on the chart itself.
  • The Dutch chart shows FIS sector boundaries on a little inset map.
  • On the back of the German chart is a handy diagram showing how the air-space structure works .
  • French and German charts do not have RPS (Regional Pressure Setting) regions.
  • On French charts, magnetic variation is shown on a little schematic map – you won’t find the isogons on the chart itself. In the UK and Germany, the lines are on the main chart.
  • In France and Italy, the charts show obligatory VFR routes (some require radio, others not) – in France these are typically out to the islands including the Channel Islands.

As with all things in flying, a little study beforehand is always worthwhile!

 

More SkyDemon tips

Posted on July 26, 2019 by - Navigation - PPL, Planning tools, Tips

We’re just back  from a fly-out to Brittany. It didn’t go according to plan due to incoming bad weather. So we were improvising our routes. This led me to jot down some tips for using SkyDemon away from home.

Before you go….

  • Invest in a ‘chunky battery’ – a 20,000mAh pack costs around £25, and guarantees power all day, probably several days, on the greediest smartphone
  • Find a way of securing your SD device in the cockpit, out of direct sun – with this week’s temperatures most devices will overheat and shutdown
  • Make sure all routes and relevant aircraft profiles are saved to Cloud, so they are accessible on your mobile device
  • Print airfield plates from original source before leaving. Generally the AIP plate contain more info than SD plates. Alternatively save airfield plates from SD to your device as PDF’s
  • For planned routes, pre-print PLOGs with no wind, GS, heading, time

And while away…

  • Fill out the pre-printed PLOG with the heading, GS and time for the day’s conditions
  • Don’t rely solely on SD just on your mobile device – it could fail, overheat etc
  • While flying, put the mobile device in flight safe mode – the GPS still works and it saves power.
  • For new routes, copy the SD PLOG onto a standard blank PLOG – Pooley’s or whatever brand you prefer
  • On a group fly-out, appoint one person to prepare new routes , and share them by email, WhatsApp etc

 

Best practice PLOG

Posted on March 16, 2019 by - Flight Performance and Planning - PPL, IMC rating, Navigation - PPL, Tips

Do you find that there isn’t enough space on your PLOG to make notes and record clearances?

Have you ever mis-read the columns and flown your ground speed as a heading?

You choose to climb to avoid weather but the base of CAS is hard to read on the chart and is not on your PLOG?
After lots of experimentation and input from students, I have printed some new and improved PLOG pads for VFR and IFR flying. The IFR PLOG also contains all the elements which a VFR CPL pilot needs.
They are designed for clarity, and to avoid the kinds of reading errors which are commonly made on a  crowded A5 PLOG. Guidance on how to use them is given on the Downloads area under Planning Tools.

If you would like some sample sheets to try out, please get in touch.
They are also  available as 25 or 50 sheet pads at a modest cost.

How do you use Skydemon?

Posted on February 15, 2019 by - Navigation - PPL, Planning tools, Tips

It was too windy to go flying last week, so I spent an afternoon thinking about the different ways we can use aviation planning and navigation app’s. I have been a SkyDemon user for some years but I think that this blog is equally relevant to other app’s like EasyVFR and Runway HD.

We can use the app’s in 4 main ways – planning, in-flight navigation, traffic alerting and de-briefing.

In planning mode, we can use it for

  • Planning a route and cruise altitude, avoiding CAS and operating above MSA
  • Checking weather & NOTAM’s
  • Identifying high terrain
  • Creating a navigation PLOG
  • Generating a Frequency list
  • Printing a charts and airfield plates
  • Planning the circuit join
  • Filing flight plan & GAR forms

In flight
I believe Skydemon is best used as back-up to primary navigation using a chart, for occasional position checks and general situational awareness. In that context its commonest uses are for

  • Airspace warnings
  • Terrain avoidance

But it can also help in

  • Finding a difficult-to-spot airfield
  • Emergency navigation e.g. unexpected IMC, VFR on top (flight above cloud), diversions
  • As a back-up instrument set (e.g. GPS altitude, track and Ground speed)
  • ATC position reports
  • Electronic flight bag (EFB) – holding a PLOG, airfield plates, and notepad
  • Joining the circuit
  • Flying a final approach track and glideslope

Traffic warning
The use of SkyDemon and similar app’s for traffic awareness and alerting is growing. They typically use a wi-fi link to onboard EC (electronic conspicuity) devices.

De-briefing
Once we’re back home, the record of our flight helps fill out the log-book, and we can review how we actually did against our planned route and altitude.Whatever your use of the app, it is important to understand the functionality before climbing into the cockpit, and also to check that it is set-up appropriately and consistently for your flight. To help with that, I attach this little check-list.

Happy flying!