LTMA

[John Lygo]

Tim,
Attached is my flight plan from Leicester to Biggin Hill. The leg under discussion is that from Little Horwood to Woodley. As I hover the cursor over the flight line, the various altitude restrictions are shown in the plan at the right hand side.  As the cursor gets to Whitchurch so the new altitude restriction of 2500 ft appears alongside one of 3500 ft. The ICAO half mil chart and Plan-G indicate that the LTMA starts just south of Aylsbury with an altitude restriction of 3500 ft. As far as I can make out the 2500ft restriction doesn't start until just south west of Booker on my flight line. So what are the extra restrictions of 2500 ft doing much further north? Perhaps I am misinterpreting the information? However, an explanation would be much appreciated please.  :)
As an aside, I am hoping to be at the Flight 1 Open Day at Shoreham in October - will you have a demo there of Plan-G?
Kind regards,
John.

[Don Fraser]

John,

A little late but did you ever get an answer from Tim? It seems that the LONDON TMA 3 3500' pops up in a lot of other places in PLAN-G but not on the 1/2 mil. Anyone know what are the differences between the TMA's. For example - west of the MID VOR it shows TMA 3 Class A 3500' and TMA 4 Class A 3500'? 

Don

[tim arnot]

One of thee shortcomings of Google Maps is that it cannot hit-test polygons, and so Plan-G can only report that you are within the bounding rectangle of an airspace. If the airspace is an irregular shape, there's a chance that you won't be within the airspace itself even though you are within its bounding rectangle. In areas of very complex airspace, such as the London or Paris TMAs, there's a good chance you will see several false 'hits'. for any given point.

[Don Fraser]

Thanks Tim that make sense. But what about the difference in  LTMA3 and LTMA4 I cannot see any reference to them on the 1/2MIL or again is that a Google thingy?

Don

[John Lygo]

Thanks Tim & Don; I'd forgotten all about that query.

[tim arnot]

No those names are not on the Chart. They come from FS. Whether FS got them from the CAA or not, I don't know.