Rights of Way

August 3rd, 2011 by PHC | Permalink


Right, Right and Right…..The aircraft ‘on the right is in the right’, if two aircraft’s are converging it is for the aircraft who is not on the right hand side to give way or take appropriate measures to avoid collision.

If approaching head-on, both aircraft’s should manoeuvre to their right hand side to avoid collision

When overtaking, the aircraft being overtaken has right of way.  The overtaking aircraft must keep clear and perform the overtake by manoeuvring to the right hand side of the aircraft being over taken.

Right of Way Order of Precedence

  1. Aircraft Taking Off or Landing
  2. Vehicles Towing Aircraft
  3. Aircraft
  4. Vehicles.

Note: Being under Air Traffic Control (ATC) direction, does not alleviate the Pilot In Command (PIC) of responsibility of avoiding collisions.   Even under ATC guidance the PIC is responsible for avoiding collisions and the rights of way still apply…….as with all instructions from ATC, if you cannot comply – tell them and don’t!


Under Visual Flight Rules (VFR), flights will have a tendency to follow natural/major land marks (e.g. railway lines, rivers etc.).   When doing so the aircraft must fly on the right hand side of that feature (thus keeping the railway or whatever on their left).

This aims to ensure that if two planes are following the same feature in opposite directions, that a head-on collision would be impossible.

Barometric Pressure: QNH / QFE

July 31st, 2011 by PHC | Permalink

Cessna 172 AltimeterAltimeters give a measurement with respect to air pressure, they are therefore essentially a sensitive barometer.  It’s the age old way of measuring an aircraft’s altitude and as such the equipment is arguably more robust than ‘modern’ advances such as GPS.   Additionally not all light aircraft have GPS fitted, so it’s important to know how it works and what it is actually telling you (not necessarily your altitude!).

Altimeters can only tell you:  Vertical distance above the datum selected.

So if you leave the altimeter alone for long enough and just keep flying at a ‘constant’ indicated altitude, as pressure changes – so will your real world / true altitude.  This is because if the pressure goes down and you keep flying a ‘constant’ altitude on the altimeter, you’ll actually be descending.   Thus the saying “High to Low, down you go….”. The reverse is equally true, giving the saying “Low to High, up you fly.”

It’s what can cause pilots crash into hill sides.

To avoid this problem, the altimeter needs to be regularly calibrated against a known pressure (datum).   There are three types available:

  • QNH : Altimeter reads aircraft Altitude above mean sea level.
  • QFE : Altimeter reads aircraft Height above a set datum (e.g. height above the airfield).
  • Flight Level (FL): Altimeter reads flight level above 1013mb/hPa of mercury.

QFE is by its nature localised, but good for flying in airfield circuits (you’ll land with the altimeter reading 0ft which is reassuring).   For cross-country QNH is typically more commonly used.

QNH gives altitude relative to mean sea level, good because everything else that is high is measured with respect to sea level.   QNH once set is only valid for the Altimeter Setting Region (ASR) you’re in and then only valid for one hour.

Flight Level (FL), above the Transition Level you can fly at ‘Flight Levels’, you’ll see them abbreviated to FL35 for example (FL35 = approx. 3500ft).  Typically the transition level is 3000ft but….   Not all flight levels are available all of the time, for reasons that will remain for another post.   Above the Transition Level, the altimeter can be set to the International Standard Setting of 1013mb/hPa.    The theory behind flight levels is fairly straight forward, at this setting everyone is flying at a relative level, they’re all going up and down with respect to each other in the same area of pressure.   So even though their indicated altitudes may not perfectly match their true altitude, a pilot flying at FL35 and a pilot flying at FL40 in the same area are in no risk of crashing into each other (even if for this example they’re a bit close).

Don’t forget Temperature….

It was all going smoothly, yet it doesn’t stop there, the thing with pressure is it changes with temperature.  Consequently if you’re flying on a very hot day then the same pressure will now be at a higher altitude – the catch being altimeters are calibrated against the International Standard Atmosphere (Temperature at Sea Level is +15C with a lapse rate of 2C per 1000ft).   If the air your flying in is hotter than this, then the altimeter will be wrong and the aircraft will be higher than indicated.   Equally on a cold day, you will be lower than indicated.

All that being said, the error temperature plays on altimeters is small (but many small errors add up, so it’s worth remembering)

……..now you know why the US Military thought GPS would be a pretty neat idea!

I’m Safe

July 30th, 2011 by PHC | Permalink

Start as you mean to go on…..safely.

It likely has nothing to do with this news story, but it’s a reminder that safety needs to be at the top of the checklists at all times.

Illnness  :  Am I ill or do I have any symptoms?
Medications : Am I on any mediation that has side-effects?

Stress : Am I under undue stress (family, money, work, deadlines…)
Alcohol : Have I had any alcohol in the last 24 hours?
Fatigue : Am I well rested?
Eating : Have I had adequate nurishment?

Humans are the primary reason for accidents, but the risk can be reduced by at least flying in the best possible physical state.

45 Hours in the Air….a lot more studying!

July 28th, 2011 by PHC | Permalink

This blog aims to achieve two things:

  1. Document every step of the way to hopefully achieving my private pilots license.
  2. Keep me writing things down!   Practical is fun, revision can be tedious – but most research says you learn it faster if you write it down, so lets see 🙂

….and maybe along the way someone else will find it interesting or even useful in one way or another.

It’s going to be about flying and nothing but flying.