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Jetheat
13th Nov 2000, 19:57
If you are localizer established 12NM out and the controller clears you to descend to 2000 feet - The MSA on Jepp and Aerad in that sector is 3900 feet but the spot height on Aerads at that particular point (12 NM out) is 1800 feet.
The question is, would u descend?

Cardiff approach ILS Rwy 12

HPSOV
14th Nov 2000, 03:48
I dont know if that situation would ever really arise. If you were IMC then the controller can only clear you to his MVA (Minimum vector altitude) which will give you 1000ft obstacle clearance. Otherwise he would have to say descend 2000ft visual, in which case you would be VMC and responsible for maintaining your own obstacle clearance, and no I wouldn't clear the obstacle by 200ft!

Anthony2107
14th Nov 2000, 07:35
If for some stroke of bad judgment on the controller's part cleared you below the MVA, I would check the glideslope if your are using it making sure you are on the acceptable tolerance, otherwise check the DME distance on the approach chart and compare it with what you are given. If unsure
"ASK" him/her to clarify.
Always double check everything.




[This message has been edited by Anthony2107 (edited 14 November 2000).]

mustafagander
14th Nov 2000, 13:29
Established LLZ means tracking OK, now we intx g/s, vnav OK.
Where is the problem???

Check-in
15th Nov 2000, 12:13
If you don't have glideslope capture, or it is u/s or not available, you should only descend in accordance with the "localiser only" profile. What would be the reason to go any lower? This will usually require another distance fix such as DME, locater beacon or marker beacon. In some parts of the world ATC will issue clearances to lower altitudes and assume that the pilot will comply with any other published restrictions. Classic case is Indonesia where the MSA's are very high, but they will sometimes clear you on nonprecision approaches down to the FAF or even minima while you are miles away and still subject to terrain limitations. In Oz we sometimes get a clearance to "...ft RADAR LOWEST SAFE"
but anyone not hearing these words would be most unwise to go below the charted limits.