oicur12

Hey ye all.

I recently required a russian metar for the first time and could not decode some of the info.

Does anybody know what this means?

QFE747/996 and MT OBSC.

Obviously the QFE is 996 but what is QFE747 and obviously something is obscured but what is MT.

Anybody?

USMCFLYR

I tried multiple METAR decoders on the net and couldn't find your answer. I agree that the QFE would seem to be 996 and I would have thought the MT OBSC meant Mountain Obscruation; but I'm not sure. It should be intersting to learn this tidbit of info.

USMCFLYR

UAL T38 Phlyer

QFE is "Q-Field Elevation" (as opposed to QNH: Q--Normal Height; QNE---Q, Normal Elevation).

QFE gives an altimeter reading of Zero at touchdown.

As to the METAR, I got the translation from United's Operations manual. Russia and China largely use Hectopascals instead of millibars for altimeter settings (they also use Meters for altitudes). I learned this 10 years ago while flying the 747-400 and a lot of routes covered eastern Russia and China.

Anyway, according to the table, 744 Hectopascals is 992 millibars. Why the discrepancy? (992 vs 996). Not sure, but I would guess a slight roundoff or operator error in putting the data in the METAR (a lot of this stuff is still done manually in that part of the world, not automatically).

And I believe USMC is correct with Mountain Obscuration.

Twin Wasp

Ah, Hectopascals = Millibars. 992 millibars is the same as 992 hectopascals.

UAL T38 Phlyer

Misread the title of the Table. It is 744 mm of mercury = 996 millibars.

Otherwise, as I said previous.

USMCFLYR

But the orginal question was 747 wasn't it?
So 747 mm = how much millibars?

USMCFLYR

UAL T38 Phlyer

USMC:

I'm a dough-head; I wrote down the wrong number.

747= 996. Perfect.


If I had thought to multiply 29.92 inches times 254 mm/inch, I could have figured this out sooner. (760 mm is std day).

bubi352

China, Cuba, Russia and certain countries in Africa like Congo still use the metric system and QFE. On approach in one of those countries, you will receive a QFE setting but you can still request a QNH. Pilots should be cautious when assigned an altitude. You must query the controller if not sure. He may give you a QNH setting to later give you an assigned altitude in reference to QFE! It is your responsibility to ensure you have the correct setting or to make the conversion.

Here is the deadly scenario. You are about to land at an airport at an elevation above sea level of 3000 feet. Your destination is surrounded by terrain. You receive a QNH setting of 1013 mb and can read on your altimeter 10,000 feet. The controller now assign you to descent and maintain 3,000 feet. Little did you know that he meant 3000 feet in relation to QFE or 6,000 feet MSL. If not careful, you will descent and get yourself a nice CFIT.

shanKs

100% correct. Fortunately on arrivals and approaches the plates have the altitude conversions from qfe to qnh. If that doesn't make it hard enough let's talk about the 1950's radios they have and trying to understand their instructions with a thick accent.

Twin Wasp

You sure China is QFE? Maybe they just gave us QNH because of the way we talked. I know Hong Kong is QNH, QFE on request. Push the "metric" button and keep on going.