RobertL18C wrote:
…isn’t there a MVA chart?
MVA which is in the AIP but not necessarily among the Jepp approach charts, or MSA on the approach plate, valid within 25 NM of the airport.
…isn’t there a MVA chart?
Not always. Germany, for example, publishes MVA charts only for EDDB/F/H/M/S/T/V/W. You won’t find one for Düsseldorf or Cologne.
bookworm wrote:
How do you decide your minimum altitude?
As we have discussed many times in the past, the whole MSA, TAA thing is really a bit of a throwback to the days of Ernest Gann.
If you don’t know exactly where you are, or if you don’t know exactly what’s underneath you, then MSA is a godsend, but if you do know both, either because of GPS or Radar, then it’s a bit of a nonsense.
You can easily imagine a wide open plain, with nothing higher than a church steeple for 30 miles around, except for one humongous great TV mast stretching 1200’ up into the air. That would make the MSA for the whole area 2200’. And if you were flying a DC4 in on DR from 1000 miles away it would be a jolly good idea to respect that.
But if you have a cockpit full of gizmos, and/or ATC radar, and they are all telling you that the mast is five miles behind you, then it’s a bit of a nonsense not to continue descent.
I imagine that @Cobalt was talking about the ILS into Biggin, I recognise the scenario. The various things that keep the MSA up in that part of the world are the Crystal Palace TV mast, Detling radio mast, the QEII bridge and the chimneys next to it. If you are being vectored onto the ILS at 1800’, none of them is any kind of threat. The Thames controller knows that, we know that, our GPS Navigators know that, so there is no real practical reason to remain above 2300’. In my opinion.
Oh, and Canary Wharf and the bloody Shard :-(
Timothy wrote:
The Thames controller knows that, we know that, our GPS Navigators know that, so there is no real practical reason to remain above 2300’.
The Thames controller is happy with 1800ft because his radar vectoring chart lets him.
PS. Note that the controller’s vector chart allows him to apply less than 1000ft obstacle clearance.
