It’s a freezing morning out there today with a glistening layer of frost on the cars. We have a forecast for snow later moving in from the south west and despite the still dark outside, I can see the veil of high cloud that precedes the weather front gradually hiding the stars as it moves slowly east. All of which is at odds with the current aircraft traffic pattern – aircraft are using the easterly runway at Heathrow. A quick check on the LHR weather reveals that there is an easterly breeze below the advancing clouds. So the cold air from the east is pushing under the warmer air from the south west, forcing it upwards, which will probably result in precipitation at some stage later today.

Although it was dark when I started writing this, it is still possible to record inbound aircraft that pass over my garden, not least because they form an orderly queue! British Airways G-ZBKR was first sighting for today, inbound from Manama, Bahrain. Following closely behind was Virgin’s G-VNYL from Islamabad, Pakistan. It was slightly lighter when the first unusual flight of the day passed over. This was Azur Air’s Boeing 767, VP-BRA. More of a mystery to this one – inbound from Krasnoyarsk in Russia, it appears to be a positioning flight rather than a passenger service. If you want to see images of these aircraft, open up the Jetphotos website and search for the registration.

The wind direction prevents me from seeing any inbound flights from the US and Canada this morning as they will have a straight-in approach to runway 09. The weather affects what I can see from home quite a bit. Ignoring the localised cloud base which can mean that nothing is visible some days, even global weather can have a significant affect on my spotting. The Polar Jet Stream moves in latitude, driven by changes in heating by the Sun and other factors like Ocean temperature. Commonly during the summer months it is further north and transatlantic traffic comes in via Bovingdon and passes over me on the way to intercepting the glideslope for runway 27. In the last few weeks the Jet Stream has been more to the south and this results in those transatlantic flights taking a southern circuit to approach Heathrow’s runway 27, so I haven’t been getting my early morning United, American and Air Canada flights anyway.

In a previous ‘Watcher’ post I mentioned the disappearance of passenger Boeing 747’s from the skies as airlines cut their costs in the face a huge fall in passenger numbers. Most have gone into storage and I doubt that many will return to the skies though some will be converted to freighters. Long haul passenger flights will almost certainly become exclusively twin-jet operations using the likes of Boeing 787 and Airbus A350 aircraft. It’s not just the Boeing 747 that has been disappearing. The Airbus A380 is also going out of service with most of its operators and production is due to cease this year. However, Emirates are still flying their A380’s into London Heathrow, here’s A6-EOT turning from Lambourne to take up a vector to intercept the glideslope for runway 27…

…I estimate it’s overhead Chigwell – that’s over 10 miles from me and gives some idea of the size of these behemoths of the skies. It’s worth looking up the Airbus A380 on Wikipedia to read about the design concept and how changes in the way airlines operate have killed it. Also slowly disappearing is the Airbus A340 – once a very economic option for long haul, it too has been overtaken by the twin-jet revolution. Lufthansa was the largest operator of the type with 62. Their fleet has shrunk to 24 and the airline is upcycling one of its withdrawn aircraft as aluminium luggage tags! I was lucky enough to see D-AIGV pass high overhead just last Friday, inbound to Frankfurt from San Francisco.

Northolt has been relatively quiet recently but I did get to photo French biz-jet F-HBZA, a Cessna 550 Citation II as it passed overhead…

Anyway, it’s now light outside and it’s time to go feed aviators of the feathered variety 🙂

So back flying aircraft, albeit in a simulation, I thought I’d show the differing types of panels a pilot is likely to come across in general aviation aircraft. Let’s start with the modern Cessna 172SP…

This panel has a layout of instruments common to most modern aircraft often referred to as the ‘Standard T’ because the key instruments are mounted together in a T configuration. If you look at the dials above the control column to the left of centre you will see in the top row (left to right) the Air Speed Indicator, Artificial Horizon and Altimeter. These critical gauges tell you how fast, how level and how high. Immediately below the Artificial Horizon (AH) is the Direction Indicator (DI) – that tells the direction you are flying in and forms the base of the T. That’s not to say that the instruments either side are not important, just less so. On the left is the Turn and Slip indicator – it’s a guide to how well you are flying but also a key back-up to the Artificial Horizon when there is a vacuum failure – it’s electrically powered. To the right of the DI is the Vertical Speed Indicator (VSI) which is air pressure driven – again, it’s a guide but is also a key back-up for the AH when the vacuum fails. Finally, below the VSI is the rev-counter for the engine. Although important, this instrument isn’t normally part of your basic scan even when flying in cloud because once set it shouldn’t change unless you forgot to adjust the throttle friction;-) To the extreme left are the engines and systems gauges – fuel, oil, vacuum, etc. To the right of the T are the navigation instruments associated with the avionics – something for another post. Oh – and that thing sticking up above the dash is the Compass – also an important instrument!

There’s an irony not lost on most UK pilots that the RAF devised the Standard T shown above after a lot of research on the best layout of instruments. That was in the 1930’s and yet a lot of General Aviation aircraft were still being built with non-standard layouts up until the 1970’s Here is a 1966 model Piper PA28-140 panel…

Let me say from personal experience that this is not a one-off layout built on a Friday afternoon and that two aircraft from the same batch could be delivered with different layout dependent upon the avionics build requested. Our Cherokee 140 (a 1967 build) had her instruments all over the place like this but not in the same locations. Also note that I’ve hidden the control columns so you can easily see everything including the switches below. I think the best policy is to talk about each instrument in ‘T’ order so, the Air Speed Indicator is exactly where you should expect it to be. The Artificial Horizon has however been displaced to the right with the DI taking its place in the centre of the panel. In the centre of the panel where the DI would be is a clock – just about the least useful thing to put in a pilots central field of vision. The Altimeter has found itself displaced to the left and the VSI to the extreme left. The Turn and Slip is hiding down on the bottom left. As for the engine rev-counter – that’s over on the right and at a difficult angle to read correctly. The engine and fuel gauges are grouped quite well on the right but the vacuum gauge is again so far over that it’s difficult to read easily. And the compass? That’s actually in the panel on the extreme left at the top. This is a VFR build but many VFR builds were adapted for Instrument flying at a basic level. In our aircraft the compass was relocated to the central window pillar and the top left slot held a radio navigation instrument known as an ADF – perhaps more on that in another post. I seem to recall that the clock was replaced by the turn & Slip in our aircraft and another radio navigation instrument (VOR) took the place of the T&S occupied on this dash. And I’m sure that the Artificial Horizon and the DI were swapped in our Cherokee. By the way, that red blob in the centre of the dash is the Stall Warning Light. There was an audible warning too. Unless very close to the ground, a stall in a Cherokee 140 is a non-event unlike some other types 🙂 So now I’m off to do some General Handling of the Cherokee to remind me of her foibles compared with the Cessna 172SP. I suspect that a bit more skill will be needed to fly smoothly and execute a good approach and landing even in a computer sim!

PA28-140 Cherokee over Clacton