Minimum Radar Vectoring Altitudes

[doubleoh]

This issue seems to come up regularly around this time of year but never seems to be resolved.

The topic is: Does ATC compensate for cold temperatures when giving RVs?

I know for a fact that Canada does. But while I was flying in Europe I was told that this is not the case. No documentation to back this claim up just heresay.

Anybody know for sure in other countries?

[Lock n' Load]

I don't know of anywhere in NATS which takes temperature into account, and indeed I'd never even heard of its affect on altimetry until I got to Canada.
Bear in mind though that the sort of temperatures dealt with here are much more extreme than is usual in the UK and Europe. We have an MVA chart for 0 to -20 which adds 200 feet to most MVAs, and one for below -20 which adds another 200 feet. Given that the first 200 feet is needed at -20, UK temps will probably never lead to an aircraft being more than 50 or maybe 100 feet low, and MVAs are designed to give at least 1,000 ft of terrain clearance to start with.

[doubleoh]

Thanks Double 'L'!

Yeah, that kind of jives with what I experienced in Europe. The only point of note was Innsbruck, where MSA to the N was 9500' and 14000' to the south. When temperatures dropped below -10c ATC advised of the low temperature and it was expected that a correction woud be made by the pilots.

However, I don't think that they had any temperature corrected MVA charts...

Anybody else?

[Hay Day May Day]

Interesting!

So what about the Middle East? Temperatures reach the 50s in the summer, should you then give -200 feet?

[doubleoh]

As far as I know nobody ever hit a mountain by flying HIGHER thsn what was safely required... :)

The point is as long as ATC is informed what indicated altitude you are flying at they can still maintain seperation with other aircraft...

I'm just trying to find out if any other states besides Canada actually correct their MRVAs to ensure terrain seperation in extremely cold weather...

[chevvron]

In the UK, QNH for the radar vectoring altitude is always calculated from QFE +/- a temperature correction, which varies according to what the QFE actually is. All airfields should have a chart to do this, in case their auto system (if they have one) fails; it should be supplied by the Central Met Office. I think they're calculated originally taking airport elevation into account.

[caba]

In Germany we do have slightly higher MRVAs during winter, e.g. from October to March. Even during Surveillance Radar Approaches we have to use different altitudes when temperatures are below 0°C.

[eldbs]

In Norway the Altitude gets adjusted for temperature.

This raises interesting problems when you are flying from coastal to inland fields over mountainous terrain in class G airspace. Especially where there is a 10 degree plus variance in temperature between fields - at which point do you make the adjustment en flying between the fields.

[Dick Whittingham]

There are threads in Tech Log and Wannabees on this subject. I note we are dealing with radar vectors here. Is there any suggestion that ATC would give min altitudes or heights after the FAF that have been corrected for low temp?

Dick W

[Pierre Argh]

Many years ago I questioned altimeter temperature correction, and was told that (in the UK) this was a factor applied by the pilot as and when ... not that we see temps in the range -20 at ground level in the UK that often!!! Interesting to see what others in colder climes do?

[Lock n' Load]

Incidentally, I posted previously with a hangover so the correct figures should be an additional 100 feet for 0 to -20 C and 200 feet for below -20 C for most RVAs. Some go up by more, generally the higher ones.