ATIS OF EDDF

[wingtip777]

There was one sentence i couldn't understand about the EDDF ATIS i heard few days ago. it was after the runway in use and "headwind on final more than 25knots", sounds like "temprature inversion 3800** degrees Centigrad"。 maybe it is still in the ATIS, will be very appreciated if anyone could hear it now and explain to me!

[DBate]

I don't think it is still on the ATIS (too lazy to check), however what they mean seems pretty clear to me; there is a temperature inversion at an altitude of 3.800' of xx°., i.e. the temperature passing that altitude is by xx° higher than on the ground. This can be relevant especially during departure as you can expect a sudden 'loss' in thrust and/or speed.

The information given on the ATIS is a kind of 'heads up' by ATC.

Regards,
DBate

[STBYRUD]

They often have warnings like this on there, as you mentioned most often about strong headwind, inversions or maximum winds if there are very strong variations.

[wingtip777]

DBate
thanks a lot!
someone put the audio on the net. would you like to listen if you have time? or i can send you email with the audio record. it sounds 29degrees, isn't it too high to be reseanable? listen the audio!please!(WSSS) | LiveATC.net

[DBate]

@wingtip

Hi there,

just listened to the recording. It says 'temperature inversion three eight zero zero feet - niner degrees centigrade'.

So it's a temperature inversion of 9° at an altitude of 3.800'. That's not unreasonable. Can't hear anything saying something about 29° .

Cheers,
DBate

[wingtip777]

DBate
does that mean the temprature at alt 3800feet is 9 degrees, or is 9 degrees higher than the ground temprature, or 9 degrees higher than the temprature should be at 3800feet? tks!

[OK465]

I believe that's a relative 9 degree rise from whatever the OAT is when you exit the underlying colder air on climb-out and enter the overlaying warmer air of the inversion. I would think this specific info is from PIREPS not the wx guys. (Vice-versa for descent)

Could be good conditions to melt off the ice each time around if you're doing multiple practice approaches in low altitude icing conditions.

[DBate]

does that mean the temprature at alt 3800feet is 9 degrees, or is 9 degrees higher than the ground temprature, or 9 degrees higher than the temprature should be at 3800feet?

OK465 already gave you the correct answer to your question. It is a relative rise to the OAT - usually given in realtion to the temperature on GND, since only few pilots monitor the OAT during climbout.

To give you an example, let's say the OAT on GND is 15°C, so with the information given on the ATIS you would expect it to be at 24° at 3.800' instead of the ~8° it would be in an ISA Standard Atmosphere.

But don't overdo this whole theory thing. As OK465 also correctly said, the information about temperature inversions is usually coming from PIREPS, not from the MET office and is given as a warning for departing pilots (a temperature inversion is much more interesting for the departing pilot than it is for the one on descend for approach since the latter will experience an increase in engine performance, while the one on departure will have a decrease in engine performance).

So the only thing I do when this information is given on the ATIS is to keep in mind that I have to expect a decrease in climb performance due to the higher temperature. And if you are already flying on AP (I am usually still flying manually at that alt.), you should be prepared to take over and decrease the pitch slightly, since some AC APs are a bit slow to react to a sudden temperature inversion during climbout.

Cheers,
DBate

[wingtip777]

got it! thanks to DBate & OK456!