Not all variables in FS are available for porting into gauge design. The full list of A:Variables is pretty impressive but when you have been using them for a while you begin to see the gaps. For example there are A: variables for wind, pressure and temp but none for dew point, cloudbase or visibility. If these are not present in the DLL's then you can't code XML for them. The only way you can make such a gauge is to ignore TA and build a simple altitude alert gauge. For this you would have to dial in the TA as the alert height and set the trigger to zero rather than 1000ft as in the default AA gauge. In the UK this is the only way you can do it because there is no way the sim will know that the TA for places like London is 6000ft, Birmingham 5000ft and Norwich is 3000ft. Very few countries have a TA of 18000ft as the TA is normally calculated on the highest ground within the country. If you fly on Flight Levels you have no idea how high you are above sea level and therefore no idea how close you are to high ground. Only QNH gives you this information. For this reason QNH is always in use as you get near high ground and so the TA is determined relative to this. There are exceptions. Some countries have no high ground at all but set a TA of 10,000ft. A very few actually have the TA below the highest peak in the country but do this because the area is considered well away from any regular aircraft operations. bones -----Original Message----- From: jhb_airlines-bounce@xxxxxxxxxxxxx [mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of FrankTurley@xxxxxxx Sent: 14 November 2006 18:35 To: jhb_airlines@xxxxxxxxxxxxx Subject: [jhb_airlines] Re: A question of altitude In a message dated 14/11/2006 10:20:40 GMT Standard Time, bones@xxxxxxx writes: Transition Level won't be a variable because it varies from country to country and can vary within areas within a country (like the UK). If you are flying any posh aircraft with built in altitude alert - the one that dings at you as you approach 1000ft to go to target altitude - a crafty dodge is to dial in 1000ft above TA rather than your cleared level. When it dongs reset altimeters to 1013.25 and dial in your cleared level. bones Er, if it were a variable then presumably one could change it, unlike the constant it appears to be? My planned gauge would warn the pilot as TL was hit in either direction, up or down. Frank T.