Light At The End Of The Tunnel
This week's song of the week has been running through my head again and again since I first heard it playing, so here it is for everyone else to enjoy too!
Monday started with another fond farewell at Phoenix Sky Harbor Airport as Mum and Dad boarded their flight back to Las Vegas before heading home later in the day.
I'm always nervous whenever it comes to catching flights as I worry that some new ridiculous rule will be revealed once you've checked and and you're trapped at the airport. Luckily, everything went according to plan and Mum and Dad safely arrived in Vegas in time to spend the day shopping, eating and still had enough time to learn once again why gambling doesn't pay! By Monday evening, the internet showed that their flight back to the UK had taken off on time and was crossing the Great Lakes as I curled up in bed for the night.
This map shows the great circle route to be flown by the aircraft. I spent hours and hours practising great circle track calculations for my Airline Transport Pilots Licence exams and began to think that I would never have to use them, but what do you know? On Monday, I couldn't sleep so I ran through a few in my head :)
The great circle is the shortest distance between two points on a sphere. Everyone knows that the Earth is not actually a sphere, but an oblate spheroid, however it's close enough that the calculations are still valid. The problem with following a great circle is that the ground track is constantly changing and this means that you cannot follow a compass bearing when flying (because if you did, that would be a rhumb line! (unless you happen to follow the equator which is both a rhumb line and great circle line)). Conveniently however, radio waves always follow the shortest path, so following a radio beacon such as a VOR, NDB or TACAN means that you follow a great circle route. The problem with that is that there are no radio beacons in the Atlantic Ocean, but there is an organised track system which swaps direction twice per day and is arranged so that aircraft can minimise headwinds and maximise tailwinds when crossing the Atlantic. Each route has a series of waypoints for aircraft to pass through and each track is laterally deconflicted so that aircraft can fly across the ocean without the need for radar tracking. It also means that they follow a pseudo great circle line by flying lots of shorter rhumb lines, a bit like flying around a very large 50 pence piece. Clever huh?
On Saturday, I headed north to Prescott for a mountain bike ride. Trixie met a chap named Patrick when she went to Namibia with Raleigh International about 20 years ago and has stayed in touch with him via the medium of Facebook for the past few years. Patrick now works for the International Mountain Biking Association (IMBA) coordinating trail access for mountain bikers in Arizona, New Mexico, Nevada and Utah. Trixie introduced us both on Facebook when I arrived in Phoenix and we have been planning a ride out ever since. It turned out that on Saturday, there was a big IMBA ride out in Prescott, so I arranged to drive up with a couple of mountain bikers from Phoenix and join them all for a wee day out:
It was great to meet Patrick and his mates from IMBA - I was made to feel very welcome by everyone, especially when they found out I had served in the RAF!
This picture came up on Bing this week - it's St David's Cathedral. Trixie and I visited here on our honeymoon and took the same photograph, so it was a nice surprise to see it pop up on my computer! Only two more weekends apart now, I can see the light at the end of the tunnel once again!
Monday started with another fond farewell at Phoenix Sky Harbor Airport as Mum and Dad boarded their flight back to Las Vegas before heading home later in the day.
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| And they're off :( |
I'm always nervous whenever it comes to catching flights as I worry that some new ridiculous rule will be revealed once you've checked and and you're trapped at the airport. Luckily, everything went according to plan and Mum and Dad safely arrived in Vegas in time to spend the day shopping, eating and still had enough time to learn once again why gambling doesn't pay! By Monday evening, the internet showed that their flight back to the UK had taken off on time and was crossing the Great Lakes as I curled up in bed for the night.
 |
| KLAS - EGLL |
This map shows the great circle route to be flown by the aircraft. I spent hours and hours practising great circle track calculations for my Airline Transport Pilots Licence exams and began to think that I would never have to use them, but what do you know? On Monday, I couldn't sleep so I ran through a few in my head :)
The great circle is the shortest distance between two points on a sphere. Everyone knows that the Earth is not actually a sphere, but an oblate spheroid, however it's close enough that the calculations are still valid. The problem with following a great circle is that the ground track is constantly changing and this means that you cannot follow a compass bearing when flying (because if you did, that would be a rhumb line! (unless you happen to follow the equator which is both a rhumb line and great circle line)). Conveniently however, radio waves always follow the shortest path, so following a radio beacon such as a VOR, NDB or TACAN means that you follow a great circle route. The problem with that is that there are no radio beacons in the Atlantic Ocean, but there is an organised track system which swaps direction twice per day and is arranged so that aircraft can minimise headwinds and maximise tailwinds when crossing the Atlantic. Each route has a series of waypoints for aircraft to pass through and each track is laterally deconflicted so that aircraft can fly across the ocean without the need for radar tracking. It also means that they follow a pseudo great circle line by flying lots of shorter rhumb lines, a bit like flying around a very large 50 pence piece. Clever huh?
On Saturday, I headed north to Prescott for a mountain bike ride. Trixie met a chap named Patrick when she went to Namibia with Raleigh International about 20 years ago and has stayed in touch with him via the medium of Facebook for the past few years. Patrick now works for the International Mountain Biking Association (IMBA) coordinating trail access for mountain bikers in Arizona, New Mexico, Nevada and Utah. Trixie introduced us both on Facebook when I arrived in Phoenix and we have been planning a ride out ever since. It turned out that on Saturday, there was a big IMBA ride out in Prescott, so I arranged to drive up with a couple of mountain bikers from Phoenix and join them all for a wee day out:
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| The IMBA crew |
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| The fast team. And me. |
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| Awesome singletrack |
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| Light at the end of the tunnel |
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| Up the rocks |
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| And back down! |
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| Patrick and me |
It was great to meet Patrick and his mates from IMBA - I was made to feel very welcome by everyone, especially when they found out I had served in the RAF!
This picture came up on Bing this week - it's St David's Cathedral. Trixie and I visited here on our honeymoon and took the same photograph, so it was a nice surprise to see it pop up on my computer! Only two more weekends apart now, I can see the light at the end of the tunnel once again!
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